Conflicting Obd And Other Issues - Corolland: the Toyota Corolla Forums

Ok, so I just bit the bullet because my 2001 with about 250k on it gave me the flashing check engine light. Was running sometimes good, sometimes not. ALWAYS burning oil and for the last few months was burning to empty about every 300 miles. p0420 and p0171 since I've owned it in 2008. Cruise control did not work ever since I had it.

Well,--- I HAD it, and decided, new (used) car or, new engine. I opted for a new engine as it was cheaper, potentially, since another used car would cost at least that much and possibly have just as much or worse issues.

Got a Jasper (please, I know they have a bad rep but the shop I took it to is trustworthy imo).

So, when you get a rebuilt, it usually does not come with sensors and such. I had already had the upstream O2, and CAT replaced at another shop, also trustworthy IMO. I did buy my own MAF prior to the new engine and it did seem to help a bit but the engine was really toast so it didn't make that huge a difference. There are also new plugs in this now so I don't know what they put in.

So everything drove AMAZING for about two weeks and then I got a CEL. Went to Autozone, said p0172. Shop told me MAF checked out as faulty... the NEW one but.... yes, I got it on ebay. I think the brand was Sumito?... it was $25, but the car was running great. They gave me a price to get it changed and I was like, uh no, I'm not paying you an hour or two of labor to just undo two screws and unclip something. So I remembered the first time I had my CAT changed the first shop said they cleaned the MAF and I do remember it running quite nicely for a while, so I still had my original MAF so I cleaned that and threw it on. Drove perfectly fine for about 3 weeks, and today I got a p0171.

So now I am confused. What is the possible reasons changing to one MAF will trigger rich and the other will trigger lean? I will check for leaks and stuff but really, I feel like it's probably the MAF. Just not sure why they would act differently (I'm not a mechanic obviously). And if that is logical, that the original Toyota MAF would trigger lean, the ebay MAF will trigger rich, and so, most likely, something wrong with both of them?... Also car does not run as nice with the Toyota MAF in. With the ebay one it runs really nice. Should I try cleaning the throttle body too?

Second, there is a humming like, whirling noise coming from either the front or rear driver side wheels, I can't tell which, that manifests most at about 28 rpm. Also some slight rumbling all around mostly towards the end of each drive to and from work (about 40 miles each way at 75+ mph) I did just have the calipers replaced because there was this terrible intermittent rumbling (I could feel it while driving) a while back and I was told my caliper on one side had seized, which I had already guessed since as it got worse I also noticed when coming to a stop and letting off the brakes my car would stay still and I'd hear creaking from the brakes like they were barely engaged, step lightly on the gas and it would creak more but the car wouldn't be moving. So that was fixed, and now I feel like that's coming back but I can't tell if it's just cause the roads are bad here. I had someone look while I was stepping on the brakes in neutral and they said they could see the calipers moving in and out but not by much. How much are they supposed to move in and out? I did see some videos about crimped brake lines but these look fine and I'm sure they were changed when the calipers were changed, they don't look nearly as old as they should if they weren't, but my wheels feel hot. brake fluid is topped to max. Also, I have a premium trim, wheels are stock alloy, it looks like the calipers (or sliders) they put on are too big. They look REALLY close to the wheels, but I assume if they were too big, there would be a really loud rattling and very heavy metallic bumping. Are these supposed to sit so close to the wheel?

Third, the whining humming whatever noise I assume could also be my struts. They are old. I did change the rear a few years ago, but I don't remember ever changing the front. Boots are torn on the front. Sound like the struts or possibly wheel bearings? Was thing of taking it to Les Schwab for an opinion.

Fourth, kickdown cable. Does not retract unless coerced. I saw a vid on unclipping a retainer under the plastic engine cover would un-kink the cable, I'm assuming from resistance after the metal sleeve where it probably gets hung up where it meets the rubber part of the sleeve. It seems like this is a common problem, but I don't see speak of it very much other than people talking about transmission shifting problems. Are there only like 3 corollas in the world that this cable is loose on? TBH I thought the whole time this was extra cable for the throttle body, then I thought it was a cruise control cable, and finally I found two videos about it listed as "kickdown" cable. Apparently this is supposed to be called a Throttle Valve cable or "TV" cable... which is kind of funny when you abbreviate it like that. Anyway... is there a fix for this? That DOESN'T involve taking off the transmission pan? OTHER than unclipping from the retainer?

... btw, cruise control now works flawlessly. I thought originally that it didn't work because of the CEL since I've owned it, but after the swap, EVEN WITH the CEL on, cruise works just fine.

also, the jasper ended up being about $6k. A new used car would have run me about that and might have still needed another engine anyway so, I feel like it was worth it. brakes and stuff are gonna happen on any car anyway, but the oil burning was just horrid and I'm glad I no longer have to deal with that. though I did enjoy all the test drives I had. 2012 prius and 2013 corolla s was pretty nice. Though my fave was the 2005 2.5i Impreza... mmmm, POWER, TORQUE.... but yes I'm a Toyota fan at heart and always will be. thought I would be getting better mileage though. Before swap I was getting 34mpg or more. That hasn't changed with this engine. Or was all that oil that was previously getting into the cylinders counting as extra fuel? LOL!

anyway, ... help please? and thanks in advance!

So did you end up with a new engine, remanufactured, or rebuilt? You mentioned new engine earlier in the post, then it sounds like they ended up rebuilding the engine.

Another question is if they used a revised piston and ring setup or modified an older set. Not all the 1ZZ-FE were oil guzzlers - but it would be a shame to put an engine together an not go the extra mile of enlarging or adding more oil drain holes, just to CYA.

Two different MAFs reading slightly differently it not unusual. Ping ponging between lean and rich is unusual - but I don't think it is related to the MAF. Sounds more like an issue with a bad upstream O2, possible exhaust leak close to the sensor, vacuum leak, fouled plugs, faulty or clogged injectors, more.

Electrical issues - especially chassis ground problems can cause some headaches. Since you MPG is pretty decent, I'm leaning toward an exhaust or vacuum leak somewhere. If you have access to a data-logging OBD-2 scanner - that could give you an idea on what the ECM is actually doing (fuel trims, timing advance, etc.)

Humming noise from front wheels - that sounds more like a bad wheel bearing / axle not fully seated into the hub. As for the caliper moving when you actuate the brakes - normal. Same with the caliper that comes physical very close to the wheels - I've had wheels that came within 1/16" of the caliper (fixed mount) and 1/8" on a sliding setup like the Corolla - both with new, thick brake pads.

TV/Kickdown cable - the procedure will be the same on a number of different models - if you want to see a video of it. Nothing to play with on the transaxle side - assuming that it still will kick down a gear, when you floor the accelerator. Just take up the slack at the flange/clip area. It is possible that the cable is stretched out / sticking. You'll have to play around with that a bit to see exactly what it is doing, sticking cable (doesn't want to go back into the sleeve - just hit it with some graphite dry lubricant / spray silicone / etc.) If the cable is stretched (cannot fix with the adjustment screw) - you'll have to get a little more creative. Might have to look at the end of the cable and see if you can move that barrel on the end.

The warranty pamphlet states "remanufactured". I don't know about the pistons but there's a warranty upgrade that I can add on (for a higher hourly labor rate) and I was planning on asking about the pistons when I called them for that.

I can check for leaks and check the plugs, but how do I check the injectors? Also if it's not the MAF, and I look on a scanner, what exactly am I looking for in the readings?

I probably cannot check for bad wheel bearing because I don't know how and I KNOW I don't have the tools to take all that apart and put back together. I'm hoping les schwab can check that.

Cool, reman engine - you should be OK. Most come with some basic warranty - parts can be sourced almost anywhere, may not be all OEM parts, but they generally won't be crap part either. I kind of figured this was what you were talking about, give the amount of money you put into this project. $6K is decent price for a shop installing a reman modern 4-cylinder engine replacement, as it can be anywhere from $4K-$8K pretty easily. Can be done for less, but then you have to deal with all the headaches afterwards - ex. someone had one done for $2K, after it was swapped in - totaling all the issues that had to be addressed (couldn't pass smog, constant CEL, etc.) - that guy easily pumped in another $2K to diagnosing it. I think in the end, he ended up dumping the car.

You can test to see if the injectors are working electrically with a noid light (plugs in between the injector and the wiring harness) or use an automotive stethoscope or similar to "listen" to the clicking sound from the solenoid. Unfortunately, that will not tell you if they are working correctly, just getting power. For that - you'll have to pull the injectors and bench test them. That can be very time consuming and can be costly, depending on what is done and the shop doing the work.

The data logging scanner should output fuel trims - LTFT and STFT (long term fuel trim and short term fuel trim). These are generally reported as a percentage (% fuel error), depending on the scanner. Ideally, you want to see both of them to hover around 0% - meaning the ECM is not having to add (fix lean condition) or remove fuel (fix rich condition) by changing duty cycle of the injectors, ie. correct stoichiometric mix.

STFT tend to fluctuate a lot, that is normal. STFT "teach" the LTFT to learn new fuel parameters based on the current running condition of the engine. Time scales for STFT are in the milliseconds. Time scales for the LTFT are in the 10s of seconds. Consider the LTFT as your engine's baseline - it is a parameter that is learned as you drive. STFT tend to fluctuate +/- 10%, if they run higher than that - it will cause the appropriate reaction to the LTFT to shift the existing baseline to a new current baseline.

Example Scenario: Assuming that STFT and LTFT are at an initial 0% fuel error (ECM reset). You have a leak in the intake manifold somewhere, extra air is being sucked in that is bypassing the MAF - O2 sensor sees an excess amount of O2. STFT will spike +20% to temporarily add more fuel, LTFT sees that STFT exceeded a threshold value and adjusts itself to +10%. After 30 seconds, STFT is at +15%, still above threshold, so LTFT moves to +20% baseline, STFT now sits at +5%, doesn't exceed threshold - LTFT sets +20% as the new baseline.

As you can see, this can get pretty complicated. What you need to look for is STFT and LTFT that are WAY positive or negative. If you get wacky values, such as +/- 50% on STFT or LTFT or one is grossly negative and the other possible - then you'll have to do some extensive diagnostic work to track down that leak or possible bad sensor.

Wheel bearings - don't really need anything fancy / no need to blow the hub apart. Just jack up that corner of the car and spin the wheel. Note if it spins smoothly, that it doesn't make any unusual noises, doesn't grab or turn weird. Then grab the sides of the wheel (3 o'clock and 9 o'clock) and try and pry the wheel from side to side. Note if there is excessive movement or clunking noises. Then grab the top and bottom (12 o'clock and 6 o'clock) and try and pry the wheel up and down - noting the same as before. You really have to tub hard - have a buddy help if needed. Just make sure the correct wheels are blocked, jack stands used to hold up car, if you must use jack to hold car - make sure it can handle the weight. Do NOT use the jack that came with the car - that is just asking for the car to fall. If that goes well - chances are the wheel bearing is OK. If it doesn't pass - then that is when you need to blow the hub apart. That point, take it to a shop to do the work in rebuilding it or get a replacement hub.

Any shop can check the wheel bearings. You can get a lot more leverage on the wheels if the car is put on the lift. Just take it to a reputable place, don't want to run into a situation where a shop wants to start swapping parts on your dime. Find a shop that will actually do the legwork to properly diagnose the problem.

Well, took it to two places, both could not hear any bearing noise, both les schwab and the place I got the engine swapped at say they hear tire noise. I like how les schwab said I needed new struts. In the front. YES I DID, since I don't ever recall having those changed. But they changed them and that did not fix the problem. Still hear like a whining noise sounds like tire noise, but turns to a high pitched rattling at a certain point, just whining humming sound before then. They all say bearings are fine,--- don't know what to think at this point. I did read your (fishexpo) previous post on another thread about the bearings sounding like that when they're starting to go bad. It is really a faint noise though. I assume it's possible they start to go bad, it's soft, and doesn't turn to the growling/grinding helicopter noise or have play in it like everyone is used to, till they get really bad.

On the fuel trims though.... I still don't see how two different maf's could give two different obd codes. Or is it possible they are both bad in different ways?....

One thing I DID notice though. With the ebay one, which the brand is actually ISUMO, I notice the car feels like it has a bit more power and response to throttle. With the original Toyota Denso, feels a little laggy, not NEARLY as bad as it was before the engine swap but it just feels peppier with the isumo maf in there. The isumo I had put in prior to engine swap and car was still running bad, then good after the engine swap. After rich code triggered I cleaned the original Toyota Denso and put it in, and then got the lean code. Reset, got lean code again. I did have the lean code prior to engine swap as well with the Toyota Denso. Two weeks each time between reset and code popping up both Isumo and Denso. Air filter is new. Both give about 32-34 mpg, I use the same fuel all the time. Does that hint towards anything or is it inconsequential?

Maybe Denso is toast and I'm really running rich?.... and if so that would suggest....?

Is there not a way to just test the MAF's themselves? All the tests I've seen regarding the MAF's are specific to what the car does or how things are read when it is plugged in vs when it isn't. Haven't seen anything about how to tell if the actual MAF is functioning properly.

It sounds like from what you are saying, bad sensor or leak would cause above/below threshold. So if threshold is bad, then it's a leak or a bad sensor. If there is then no leak, then one of many sensors could be bad.... so just change them all?....

Also, should I be cleaning the throttlebody? Seen so many video's saying that can sometimes cause errors.... I doubt it will fix this but is it possible that might be a problem?

And thank you again so much for your help. I'm actually contemplating going to auto tech school to start a new career. Supposedly it's not a great job but I can't see how it's not.... cars will ALWAYS have problems and need fixing. Even in an apocalypse. I assume mech work would be in high demand regardless of the state of the world. Until then though, I do need your help. THANKS!!!

Hard to tell what the MAF is actually reading - generally you want to clear the ECM every time you change the sensor. Otherwise, it will use the baseline already stored in the ECM.

As for different MAF sensors reading differently - that could be very true. All sensors have a certain tolerance allowed to them - depending on where they sit, they could report slightly different readings. That slight offset, could be enough to cause a DTC to fall on side of a failure threshold or the other.

As for the replacement MAF giving more power - hard to find out without strapping the car to a chassis dynometer - "butt" dyno here is pretty misleading.

You can test the MAFs individually - need to have 12V power to them and hook the sensing leads to a voltmeter. Either need to make up a testpoint bridge or back-probe the connectors to get readings. You should see the voltage fluctuate when air speed across the sensing leads changes (ie, voltage increases as air flow increases). Easiest to check it while it is installed in the car - at idle, the MAF should read about 1.1V at 3000RPM will read about 1.7-1.9V.

Wiring goes: pin#1 (black) - 12V hot, pin#2 (blue w/white stripe) - MAF (-), pin#3 (green) - MAF (+), pin#4 (yellow w/black stripe) and pin#5 (brown) - IAT sensor, no polarity, its a thermistor.

Swapping parts is the easiest way to troubleshoot this sort of issue - but also the most costly. Sensors are not cheap and if you blindly change the sensors in an attempt to "fix" this - you could accidentally cover-up the real issue.

Cleaning the throttlebody is a piece of cake, if you leave it on the car. Where most people go wrong is when you try and completely disassembly the TB or remove it completely from the intake manifold. Since yours is a conventional cabled TB - it is pretty hard to mess it up, no recalibration procedure needed like on the DBW setups. A good cleaning every once and a while will really help stabilize your idle quality and potentially solve this rich/lean issue you are seeing.

Finding leaks or troubleshooting a sensor is not easy. Best way to approach it is to do all the simple stuff first - try and avoid swapping back and forth between parts until you get a good baseline of what works and what doesn't work. Then change one thing at a time until something changes. Takes a lot of time and labor to do it this way, but you end up learning a lot during this process and could find potential problem issues before they get worse.

So true on auto tech future - people will always drive cars, so there will always be someone needed some work out there. With the mix of constantly advancing electronics (cars are now rolling computers) coupled with the need to be technically proficient around computers as well as hard tools - you have the potential for lots of other possibilities down the road. May not be the right career move for some - but can't argue the need for such a job.

Myself, I started out with advanced degrees in computational physics and mathematics - pretty much looked like I'd be in a career in academia. But I liked working with my hands and building stuff to be teaching in a classroom all the time. So cars became a serious hobby for me - worked at a speed shop for several years and eventually got certified as a master tech. But working in the private sector as an software engineer for some unique customers pays the bills - so here I am, 15 years later.

As for different MAF sensors reading differently - that could be very true. All sensors have a certain tolerance allowed to them - depending on where they sit, they could report slightly different readings. That slight offset, could be enough to cause a DTC to fall on side of a failure threshold or the other.
As for the replacement MAF giving more power - hard to find out without strapping the car to a chassis dynometer - "butt" dyno here is pretty misleading.
You can test the MAFs individually - need to have 12V power to them and hook the sensing leads to a voltmeter. Either need to make up a testpoint bridge or back-probe the connectors to get readings. You should see the voltage fluctuate when air speed across the sensing leads changes (ie, voltage increases as air flow increases). Easiest to check it while it is installed in the car - at idle, the MAF should read about 1.1V at 3000RPM will read about 1.7-1.9V.
Wiring goes: pin#1 (black) - 12V hot, pin#2 (blue w/white stripe) - MAF (-), pin#3 (green) - MAF (+), pin#4 (yellow w/black stripe) and pin#5 (brown) - IAT sensor, no polarity, its a thermistor.

I think if you sat in the car you'd notice the difference. It's not so much power as it is throttle response. Car picks up faster from stop with the isumo than with the denso. Like when you are at a stop, need to pull into the moving lane. It was doing this before the engine swap. When I put the isumo on it still did, but after the engine swap that stopped. It picked up really quickly from a stop. Step on gas, car moves as it should. I'm using the same intersections as a gauge. All different times of the day. It does not matter. When the rich code came on I took it in, the shop of course said that's an "MAF" code. I know there is no such thing, but to humor their diagnosis I cleaned the denso and put it back in (yes I let it dry). It idled terribly after putting in the denso and resetting the code. smoothed out after a day but had been laggy picking up from stop the entire two weeks until the code came on again. Reset (pulled negative cable from battery), and started again. Idle was not rough this time though, but still, laggy from stop. Step on gas, car slowly starts to increase speed. Not immediate like the isumo. Although I don't disagree that me in the car is not as accurate as a dyno. "Butt dyno" LOL, I laughed hard on that one!

I'd like to know, given that I have to drive to work every day pretty much, while I'm diagnosing this, is one of these codes worse than the other. I understand an error code is an error code, and both are bad, but I have two MAF's the car will run on until this is figured out. So is one code, or rather the effects of it, potentially worse than the other to drive around with in the meantime?

Also on the bearing noise, or rather, not bearing noise, les schwab moved the tires around, it is likely the uneven tire wear as the noise sounds different now, and they did show me the tires with the car jacked up, which I didn't realize look significantly different jacked up than they do on the ground. I could see the wear was diagonal. WOW! should have done my rotations like they suggested, but I have never done them before. probably never noticed since I always had cheap tires on this car until a few years ago they suggested better tires, and they sure seem to be lasting longer than the cheaper ones from before. And I do a LOT more driving now than I did back then. Prior to this I got a new set of tires every few years due to them just going bald. The ones I have now have been about 3-4 years. Still have plenty of tread. They said it's ok to drive on them even though they're worn uneven. Just makes an annoying noise when you drive. Lesson learned. Rotate on schedule. My rear struts have been on for about 3 years now. It's likely they're going bad as the work order I have from these does not have a name on the brand or trim. Just says "rear strut" the new front ones, the work order says "Front Strut EXCEL" or something like that. Anyway.

FYI in addition to what I thought was bearing noise, there was also a knocking noise when I went over bumps on one side. Not loud, but just sounded like something loose. When they originally changed the struts and did the alignment and rotation I took it for about a week but it was pulling to the left slightly, but enough that I needed to constantly hold the wheel right to go straight. I think they just did a sucky alignment and they have a few weeks warranty on it so I took it back yesterday. When I took it in I let them know it was pulling left, still sounded like bad bearings and the knocking was still there. They checked and called back, told me bearing noise was just tires, they would fix alignment and the knocking was the sway bar linkage on the one side. Suggested changing both at the same time. Fine go ahead, not too expensive. Picked the car up this morning, immediately knocking all over the place. I thought "maybe they just need to set in?" Drove home, decided no, they probably messed up. Called in sick to work. Took it back to les schwab. Tech got in the car with me, drove around, he heard it. Pulled next to the bay's told me drive slowly with hood open, move wheel back and forth while he listened. I tried not to run him over. He says "your engine is jumping", I was like "dude. please don't talk about the motor mounts, this is a suspension problem", he agreed. Why do shops keep saying "motor mounts" for like EVERYTHING that they can't figure out? Anyway, he pulls it in, gets the car up, takes off tires, tugs on suspension in front. Can't figure it out, calls over another guy, he pulls it, says something to him, they call another guy, come back over and tell me to come in the bay and check it out. They tugged on it, linkage was creaking, both sides. They said looks like the manufacturer didn't lube these but they're not serviceable so they just ordered me a different set. Probably a really good one cause these are quiet as all hell. I hear ZERO steering/knocking/suspension whatever creaks now. Alignment is good now. Now all I hear is the annoying "bearing" like noise, and seems to be coming from the back now that they moved the tire back there.

Why can't they just do this all right the first time? While I'm sure it is not intentional, I also know it costs money when customers comeback for something, because typically when that happens you don't pay anything additional. MAYBE I didn't really need struts the first time, MAYBE I didn't really need new linkages this last time (maybe something just needed to be tightened), but they could have all been done at once, while the car was up, tires off, less time, less paperwork, and they could have still charged the same amount of labor (I of course would have argued) but they didn't listen to the car well enough, didn't do the alignment right the first time, and they didn't suggest coming back to have anything looked at or suggest future repairs that will likely be needed. Just like the first time I went in last year, brakes were clearly going out, they said they were fine, go to another shop literally the next day and they said the calipers were freezing. Have not had that rumbling issue since. They took the time to "look" at it, and didn't find anything, so the money went to the shop that actually "looked" at it. Changing calipers, I know, is not a difficult task. Easy money really, I just don't have the tools or time. Now, I love les schwab because really they do a lot of work for free. Mounting your snow tires on and off each season, flat repair, rotation, I think balancing too, but their "free inspections" seem to be pointless for both parties. It seems like you need to actually have them change something before they'll take a serious look at anything. WHY? It only took them a few minutes to identify the linkages were bad. That was part of the suspension, that they checked, the first time, when it was making that noise. Had to take it in twice for them to identify it, and they had to change it twice to fix it. Had these been on a new customers car they wouldn't have even checked.

I like to think if/when I get into this trade, I'll be more thorough. Case in point, I'm pretty sure my strut mounts will need to be changed in the future. They have never been changed. I would think when you change the struts, you'd just change the mounts too since these are not lifetime parts and now they will both be new. You already have the struts off to change them. I think you need to take the mount off at the same time anyway (my buddy did mine on my old car the last time). Yes you could charge more labor later, but you also have to do the same work again later too. Why have that come back down the road later? No guarantee the customer will even come back to your shop for it. You could spend that future hour on something else that would pay more.

Anwyay, rich or lean? Which will likely be better or worse while figuring this out?

EDIT: NEVERMIND ALL THAT, denso tripped lean code. not even 90 miles after reset. read at autozone lean bank 1. WHAT IS BANK 1? does that even matter? Anyway went home, disconnected battery put in isumo. did smoke (ecig) test no air pulling anywhere on idle or throttle. let sit at idle, came back 10 minutes later check light is on again. WHAT THE HELL IS GOING ON?!? and yes I have the maf installed correctly.

I don't have a code reader but I'll go in tomorrow and check at autozone, see what it says. should I pull battery cable again and see if it takes longer to throw the check light again?

since I don't see any leaks, at least not bad enough to pull smoke in, I wouldn't imagine a leak is the problem. what is next likely? both maf's are bad? or injectors going out? or fuel pump?

I think for sure the denso is going since it's been throwing the lean code for a while. the isumo I got on ebay for $25 is also highly suspect right? especially since I just threw it in and it tripped right away.

I am really curious either way, how could I be getting 34 mpg if I'm running rich or lean?

Just realized my registration is July so I actually have another month to figure this out but I really need some solid advice since the shop is just gonna have me replace the MAF. I could just get a new OEM one? from Toyota? or is there any other suggestions for a known good MAF? Seems like that would be the best place to start right?

Bank 1 sensor 1 is your upstream O2 sensor, and bank 1 sensor 2 is your downstream O2 sensor... P0171 lean code is a common mistery for your 8th gen Corolla... It's likely caused by a vacuum leak at intake manifold gasket or vacuum/PCV hose. Have you cleaned your MAF/IAT sensor on intake, and your throttle body and idle air assist valve?

MAF has been cleaned, multiple times. Did not clean throttle body yet, that will be next. Where is the idle air assist valve?

EDIT: just cleaned throttlebody, no i did not remove it, no i didn't spray anything down the body. used carb throttle cleaner and toothbrush wrapped in lint free rag. held open throttle from outside, sprayed the cloth that was wrapped around the brush, went to work. is not squeaky clean but did remove all the black stuff. looks like to get out the idle air i'd need to remove the throttlebody itself. don't have time for that right now. going to work soon (or going to try).

cleaned maf again, put back in car, started, of course runs fine for now.

ordered denso maf from 1976070 walmart dot com. sold by walmart not marketplace. will be here tomorrow. $80 plus $10 next day shipping plus tax so about $97. only reason I did this is I can have this tomorrow. not really for the money savings. can get from napa for $134 plus shipping and tax but wouldn't get here till next week. if walmart one is not good I can just return it.

Called the shop just to let them know what was going on. owner said that first time they had tested the isumo maf and determined it was bad. they did something with it plugged in and not plugged in with a scanner so I assume they did the fuel trims.

I can see marks on the sensor wires on the denso so I'm pretty sure it's bad anyway but at least it doesn't immediately trip like the isumo which must be bad as well. for $25 what should I expect right? i read somewhere about aftermarket maf's in general not being good. even autozone said they don't think their brand is good but only recommend because of the lifetime warranty, can just keep changing it.?... seems like they should just not sell it.

Anyway we'll see how this goes.

planning on getting a scanner since I'm sure there will always be some code popping up eventually down the road.

can anyone recommend a good scanner (not too pricey) that will actually show data (not just read codes), or scanners I should stay away from?

Lots of scanners now have the ability to pull the freeze frame data (the conditions that were recorded immediately when the DTC fault occurred). Actron, Innova, Autolink, Sunpro, etc. - all pretty similar. Prices will start around $80-$90 and go up - depending on features. Some basic pocket scanners will read freeze frame data, you'll have to review the feature list to see if they support it. To get ones that actually log in real-time - now that tends to bump the price up a little bit - looking at $100-$150 easily.

Mine is an older Innova one (3000 series) - displays in real-time - I think it retailed for about $150, picked it up from Walmart for about $90. The closest one that looks like it is the 3040a - retails for about $150, but I've seen them on Amazon for about 1/2 that price.

Because your car's behavior seems to be ping-ponging back and forth - I'm leaning toward this NOT being only a MAF issue - could be a dying upstream (pre-cat) O2 sensor. Some O2 sensors die slowly - when they do, that cause all sort of erratic behavior. One minute the car runs well - the next it barely moves under acceleration.

Doesn't always manifest as poor fuel economy - I've had a problem with a "lazy" sensor on my old Matrix but was still getting more than the EPA rated MPGs + it seemed way more power than the 180HP the engine was originally rated for (2ZZ-GE). But that car had a Jekyll and Hyde complex in terms of running behavior that was getting pretty old. Car would run like a top one way to work or home then barely make it back in the evenings on the reverse course. At times it would run normally for weeks then become almost undriveable. Didn't throw any DTC codes either. Only found out by shear dumb luck when I pulled the plugs - completely glazed, looked like blisters on the porcelain - sensor was saying mix was good, when it was actually way too lean.

My Autel MS509 I got from China for $40 shipped is perfect... It's still available, although the updated AL419 with color display is quite nice for the price from USA distributor.

http://www.autel.com/autelcms/Code%20Readers&Code%20Scanners/359.jhtml

http://www.ebay.com/itm/Autel-AutoLink-AL419-Fault-Code-Reader-Scanner-OBDII-2-CAN-Diagnostic-Scan-Tool-/271916094855?hash=item3f4f765587&item=271916094855&vxp=mtr

so, for the scanner, looking at Autel Autolink:

AL519

Reads live PCM datastream

Displays live O2 sensor test data

Graphs data (1996 and newer vehicles)

Reads, stores and playbacks live sensor data

AL619

Views freeze frame data

Reads, stores and playbacks live PCM datastream and live sensor data

Graphs data

...huh?... if I'm understanding their descriptions correctly the 519 is more capable? in that it "displays" live 02 sensor test data? so I can just watch as it happens real time on this one?

619 says "reads, stores and playbacks"... meaning it will read it but you cannot view real time?

or are they both saying the same thing, neither displaying real time data, just capture of live data?

if that's the case, it looks like the only real difference is the ABS/SRS Diag on the 619..

... descriptions are confusing to me.

it seems freeze frame would not be particularly useful to me in this specific instance since it's only going to show what happened when the code was tripped and not what's happening over a period of time. so, with freeze frame only I'd have to drive around, wait for a code trip, see what it did, fix something drive around again, wait for another code trip, see what it did. right? with live data record I could see over I'm assuming a limited amount of time but a larger time span making it easier and quicker to diag right?

Yeah, that's right. My MS509 does display live data which is great, so its successor would in fact be AL519... The AL619 does everything the AL519 does, plus the SRS/ABS diagnosis... Very nice units.

Yeah probably will be getting the 619 in that case.

Also, called Jasper today to get the premium service plan added to the engine. covers labor rates up to $125 per hour, and towing and rental coverage.

New Denso MAF came in from walmart but I already took the car in for safety and emissions. I cleaned the original Denso and put it back in, cleaned throttle body and it hasn't tripped again since the 1st, so I'm fairly certain most of the problem was the MAF itself. Again, original Denso has dark spots on the "resistor/cap" part of the wires. Since it tripped so fast last time but I cleaned it again and now I'm up to a week without CEL, cause and effect tells me at the very least the old Denso has a limited operational rate temporarily remedied by cleaning.

After I get the car back from safety emissions, I was thinking about switching out to the new MAF.

Question. Should I just wait and see how long the old one holds up again? or should I just do another battery reset and switch it out soon as I get it back?

Also, talked to shop owner about auto tech school. He said going to school is fine but real world experience is more valuable, said it would be perfectly fine for me to start out at a tire and lube shop and work up from there. ASE requires shop experience anyway, and most shops looking for actual mechanics require some kind of experience besides school, so school would help little to get foot in door and really only delay getting started. Seriously thinking about this. I'm a musician, and while it's fun, there is not much out there in the way of jobs for musicians, and definitely not anything that I'd really have fun doing. Not super lucrative either. I think I'd have more fun fixing things than playing at weddings or teaching lessons, especially if there's an economic event, not sure dj's, wedding bands, private music instructors etc, would be high on most peoples priority lists. Being able to get to work on the other hand, people needing work on their car would still be extremely necessary, and I could fix peoples cars (small stuff) on the side if they couldn't afford to go to a dealership or shop for stuff like oil changes, brakes, plugs etc.

Ok, check light came on again. This is getting really annoying.

I've had the new Denso in the car for about 3 weeks so as fish suspected, probably not JUST the MAF.

Fish, considering your suggestions for possible culprits, and no I haven't checked the code yet, assuming one or the other, I'm planning on just getting the parts and changing myself after diagnosis.

Want to plan ahead so I know where to get from and how long it will take.

Need to know part numbers for OEM O2 sensors, and fuel injectors, as that's the suggested parts at fault (besides vacuum leak).

Any other parts I should start looking at?

NOTE: that the list price is from the Toyota EPC, subject to dealer pricing. Most, if not all, can be found for significantly less than what is listed if you look around. Example - brand new injectors can range from $25-$75 each, O2 sensors can run from $20-$150 each. It definitely pays to shop around.

For the injectors - there are three main components:

- injectors themselves, two possible stampings ("J"): OEM #23209-22040 or ("L"): OEM #23209-0D040 - list is around $72/each

- injector O-rings: OEM #90301-07024 - list is around $1/each

- injector stand-offs (acoustic dampers): OEM #23291-73010 (made before 10/2001) - list is about $2/each or OEM #23291-22020 - list is about $1/each

For the O2 sensor:

- upstream (pre-cat) or front sensor: OEM #89465-09200 - list is about $250

- downstream (post-cat) or rear sensor: OEM #89465-02030 - list is about $250

As for other parts, depends on what you find out with the DTC. In your case, being so intermittent - won't lie, this will be a tough to diagnose. To compound that issue, there is no guarantee that a replacement part will be 100% functional right out of the box. Can't tell you how many times that tripped me up - brand new part, either DOA or failed very quickly after installation.

The likelihood of those parts above being truly faulty - though possible, fairly unlikely. What usually happens is when you remove them to swap with a good part - usually you'll see that either the injector o-ring is gone or the standoff is cracked - causing those funky fuel-trims. O2 sensor could be the same way - on mine, the sensor was functioning just fine - but the metal composite gasket was completely eroded away, causing a previous lean condition for me.

For the injectors - there are three main components:
- injectors themselves, two possible stampings ("J"): OEM #23209-22040 or ("L"): OEM #23209-0D040 - list is around $72/each
- injector O-rings: OEM #90301-07024 - list is around $1/each
- injector stand-offs (acoustic dampers): OEM #23291-73010 (made before 10/2001) - list is about $2/each or OEM #23291-22020 - list is about $1/each
For the O2 sensor:
- upstream (pre-cat) or front sensor: OEM #89465-09200 - list is about $250
- downstream (post-cat) or rear sensor: OEM #89465-02030 - list is about $250

Yeah that's why I was asking cause the MAF Toyota quoted me about twice what I actually found the same Denso one for.

Are these all Denso parts originally though?

Also, you posted part numbers for o rings and dampers, I assume that means new injectors don't come with them right?

Heading to get the car scanned in a bit. Didn't buy my scanner yet cause I didn't think I was going to need it for a while. Oh well.

.... ok nevermind all that....

So I went to harbor freight and got a cen-tech which is a rebranded autel al419. It was $79, really not bad price, I know I could have gotten cheaper on amazon or ebay but not by much. Plus I have 90 day return and I did get the 2 year replacement plan (yes I buy those) which I couldn't get from amazon for some reason it doesn't show the protection plan for auto scanners, even the ones sold by amazon which is weird to me.

Anyway, scanned the car with my shiny new scanner...

Stored: P0770 Shift Solenoid E

Pending: P0442 Evaporative Emission System Leak Detected (small leak)

.... no P0171 but now I almost wish that was the problem...

These codes are bad right?... It would be amazing if the evap code was just my gas cap, but I'm full of bad luck. And shift solenoid?... do I need to take of the transmission pan for that? cause I don't think I can do that myself. to buy safe equipment to lift the car plus whatever else I'd need, probably looking at the cost of labor at that point right?

I will do a record data later today... as I have no idea what I'm doing, what figures would help me pinpoint the cause of these codes?

Also the check engine light went off on my way home today.... I'm sure the problem is still there as I didn't change anything at that point, but I hope that doesn't mean I'm looking at a possible electrical or ecu issue...

On you previous post concerning the injectors - depends on where you get them. If you get them from the dealership - every piece is sold separately. Aftermarket or other retailers, may have a kit with all the parts in it - just have to look at the details closely.

Evaporative emissions codes are more of a pain than cause issues with the car. They can be tough to diagnose. My 2002 seems to pop them up exactly when I need to have the car smogged. But from a car functionality point - they don't really hurt the car. From an emissions standpoint - it is an automatic failure in many municipalities.

The P0770 transaxle code - that can pop up with cases of too low transaxle fluid, excessively dirty fluid, faulty shift solenoid or the wiring to the solenoid is bad. Have to drop the transaxle pan to get at the shift solenoid. Don't think you need to remove the valvebody inside the transaxle, but would have to see myself to be sure - haven't played with that in some time.

These series of codes: air/fuel mix issue, EVAP, transaxle, etc. - pretty hard to believe that the car is having that many problems spread all out like that - possible, but not typical for this generation Corolla. It is possible that this could point to a bad ECM or atleast the wiring running to the separate sensors. May not even have anything to do with those indicated sensors - with all the redundancy built into the system, can be something completely unrelated that just happened to upset the ECM and cause it to pop a DTC. Example: on some Toyotas, a bad coolant temperature sensor can cause all these codes to pop on - bad chassis grounds can also do the exact same thing. Sometimes something completely unrelated - like a bad tail-lamp (corroded bulb socket) or even rodents chewing the wiring can cause these codes to pop up.

Is it at all possible that a bad MAF would mask the p0770 and p0442 codes?

Are the sensors related to these two codes run through the OBDII on a scanner at all, like will I be able to see anything related to them in the live data?

Keeping in mind, I did just have the engine replaced, possible something is not connected properly right?

Odd to me that I'd still have the P0171 and P0172 after the swap, get a new OEM MAF and have all these other codes pop up...

I'll run the live and post what's on it if that would help at all.

I did also find this TSB: http://www.matrixowners.com/tsb/T-EG020-02.pdf

Granted it is for the 2003, but given the commonality between the models is it possible this is what's going on?

Also I don't know how to read those, but is it basically saying to replace in that order until the problem goes away? Speed sensor, then ECU, then Transmission? Is that Toyota saying all these parts are faulty or is it them saying ultimately the transmission is faulty?

I'm thinking the MAF is just the red herring here - I don't believe it could mask a P0770 code, EVAP codes (P044x) - possible.

As for what to look at live readings - the STFT and LTFT would atleast tell you if you are metering fuel/air correctly. The rest are just bonus / help to possibly focus diagnostic efforts down the road.

With any engine swap - anything that could go wrong, will go wrong. Possible that a sensor was damaged during the swap, or that the donor engine had a bad sensor that wasn't caught during install. Sensors can also degrade so slowly, ie die slowly, that they fall into that middle threshold region - ECM sees that it "could" be bad, but not bad enough to warrant a DTC popped up. Those can be really hard to diagnose - almost have to fall on those by accident, or wait until the sensor completely fails.

As for the TSN - the transaxles between the two generations are different enough that this would not apply to your 8th gen. Note that they run different ATF fluids, 8th gen spec'd for Dexron II or higher, 9th gen spec'd for Toyota Type T-IV ATF. There was also a jump in ECMs between the two generations - the 8th gen ran fairly low data rates, narrow bus OBD-II while the 9th gen jumped to a significantly wider bus/longer identifiers with faster throughput in preparation for the next generation protocols.

Doesn't mean that the transaxle is completely flawless - there could be something causing that solenoid malfunction. I'd reset the error codes, drive normally and see if it gets set again.

........ ok fishexpo.... It has been almost 3 months since I cleared the p0770 and p0442...

Today the light came on, went home and I had p0440 stored and p0440 pending..... WHAT IS THIS!?!

I did notice, my gas cap gradually gets loose. It's tight when I fill up full, I refill at about 1/4 tank normally and by then when I go to the cap it's a little loose and comes off easy. We'll today when the code came on, I didn't touch the cap. When I came home I ran the scanner and checked the cap, but this time the cap was pretty snug. I am about half a tank now. Does this have anything to do with anything? I have no idea what cap it is but I know it isn't the original one.

Any thoughts?

I'm probably going to just buy an oem fuel cap, just so I can rule that out.... what part number is that by the way? When I look online I see:

77310 48020

Is that correct?

Anyway, thanks in advance.

You can have your cap pressure tested - see if the rubber seal is still OK. As for the number - that points to the OEM fuel cap assembly. Only thing I couldn't tell is it just the cap or the cap + gasket (some time ago I ordered an OEM gas cap online - just got the cap, no gasket). Later I ended up getting one at the dealership directly - I think I paid about $20.

I have found that aftermarket caps can be hit or miss - the OEM is the way to go. The aftermarket Stant cap I had worked pretty well for about 2 years, then it literally fell apart in my hand as I loosened it while filling up. Was quite a bit cheaper than the OEM one I ended up getting, $5 vs $20 - I guess it is true, you get what you pay for.

P0440 code points to EVAP system malfunction. Unfortunately not very descriptive. But on Toyotas, known to point to three common possibilities. Damaged seal on the gas cap is the top culprit, followed by a bad purge solenoid valve (on the vapor canister, usually bad vacuum line or corroded connector), to bad vapor canister (almost never happens unless you got into the habit of topping off the gas tank, which could flood the charcoal with raw gas, or somehow the exterior case of the vapor canister got cracked).

I think there is an exploded parts diagram on my photobucket account, link is in my signature, if you want to see how the parts are laid out. Should find a lot of info on those parts online - as this is a pretty common problem on the 8th gen, mine included.