You must drive a lot to have put on 10,000 miles already.

Yes, indeed I do... I average about 300 miles a week just going to/from work, and it seems about once a month we make a trip to visit the soon-to-be inlaws and that's about 500 miles roundtrip... My girl drives a Mustang so needless to say when we go on long trips we take the Corolla for comfort and fuel usage. Mercifully I'll be moving in a couple months to a location that is only a mile from my office, so I won't be racking up near as many miles.

Ok, I tried checking my ECU this evening by removing my glove box compartment. I did locate the ECU, but I could not identify whether it is made from Denso or Delco. It didnt say on the visible part of the unit, so this weekend im going to literally take off the ECU and check it out that way. To tell you the truth, By comparing what I saw with the picture from the repair manual, mine looks like the delco one

Still, I can't be entirely sure yet.

I took some pics too

This is with the glove compartment removed The white "Toyota Denso 5"sticker is for the cabin fan, not the ecu.

My pos camera couldnt focus.. this is supposed to be the ECU located near the bottom

This is underneath the ECU, all it says is "Toyota Computer, engine control" and some numbers.

You have Denso. Delco starts with P/N 89666, Denso starts with 89661.

What's your MPG?

AT or MT?

Wow, you just refuted the ecu hypothesis.. thanks for the info. I have auto and I get around 24~25 mpg, half city half highway. Hmm maybe its the gas thats causing worse gas mileage, but the thing is I tried different brand/grade gas and I consistently get low mpg- maybe it has to do more with the region that I live (north east, maryland)

 

Well, it is more complicated than that. The ECUs have different model numbers, yours is 02C12. For example, I know that Delco made models 02150 (non-reprogramable) and 02154 (reprogramable) in 2003. I don't know about 2005 but in 2003 (based on the sulfur farts TSB I have a copy of) there were 4 versions of software (toyota calls it ECU calibration ID) for MT and 3 versions for AT. This is for Denso. There are 4 additional ones for Delco ECU. The problem could be software-based and not necceserely hardware-based.

I believe you have to have toyota diagnostic kit with correct software on card to check your version.

I doubt toyota will be willing to disclose this info.

 

You must drive a lot to have put on 10,000 miles already.

Yes, indeed I do... I average about 300 miles a week just going to/from work, and it seems about once a month we make a trip to visit the soon-to-be inlaws and that's about 500 miles roundtrip... My drives a Mustang so needless to say when we go on long trips we take the Corolla for comfort and fuel usage. Mercifully I'll be moving in a couple months to a location that is only a mile from my office, so I won't be racking up near as many miles.

I drive about 100 miles a day to get back and forth from my new job. That is closer to 500 miles per week. I hope to eventually move closer. It will be nice for you after you move and won't have the long commute.

 

Maybe your new car will last a little longer.

Ok, I tried checking my ECU this evening by removing my glove box compartment. I did locate the ECU, but I could not identify whether it is made from Denso or Delco. It didnt say on the visible part of the unit, so this weekend im going to literally take off the ECU and check it out that way. To tell you the truth, By comparing what I saw with the picture from the repair manual, mine looks like the delco one

Still, I can't be entirely sure yet.

I took some pics too

This is with the glove compartment removed The white "Toyota Denso 5"sticker is for the cabin fan, not the ecu.

My pos camera couldnt focus.. this is supposed to be the ECU located near the bottom

This is underneath the ECU, all it says is "Toyota Computer, engine control" and some numbers.

You have Denso. Delco starts with P/N 89666, Denso starts with 89661.

What's your MPG?

AT or MT?

Wow, you just refuted the ecu hypothesis.. thanks for the info. I have auto and I get around 24~25 mpg, half city half highway. Hmm maybe its the gas thats causing worse gas mileage, but the thing is I tried different brand/grade gas and I consistently get low mpg- maybe it has to do more with the region that I live (north east, maryland)

 

Finally, I checked mine. Very easy, the ECU is located below the glove compartment, visible from underneath.

It is 89666-02154, meaning that it is a reprogrammable model of Delco. The funny thing is that it is actually labeled "Denso, Made in Tennessee". This is contrary to my source from: http://www.autosafety.org/Toyota%2003-04%2...%20Catalyst.pdf

Nevertheless, it is different from yours so, the ECU is not the whole story here. Software/firmware? Maybe. However, mine was reflashed to comply with the sulfure fix and I did not see a measurable change in MPG. I did see some change in AT logic with fewer downshifts on mild grades.

The bigest jump in MPG I ever saw was a year ago when the dealer went from 10W30 to 5W30 oil. The city MPG went from 27 to 28 MPG. I cleaned MAF at the same time, so not clear what helped.

When I find a cheap O2 sensor, I will try a swap. Recently, I replaced O2 sensor in my subaru at 60,000 miles (despite no CEL and good histogram on OBD2 scanner) and the MPG went up 10% (city and hwy).

I just recomputed my gas mileage for my last tankfull and I got exactly 30 MPG. That is the best I have attained, so far. I use 20W-50W oil, because I drive a long distance at one time and I want the heated engine to run smooth. If I drove city miles or in a colder climate area I would probably use a thinner viscosity oil, such as 5W-30W.

I've read on Consumer Reports that 2006 corolla LE auto gets 28.6 mpg city/highway combined, 30mpg on XRS mostly highway. Those figures are less than epa estimated mpg, especially LE's gas mileage which doesnt even reach city 30mpg.

I've read on Consumer Reports that 2006 corolla LE auto gets 28.6 mpg city/highway combined, 30mpg on XRS mostly highway. Those figures are less than epa estimated mpg, especially LE's gas mileage which doesnt even reach city 30mpg.

Doesn't seem very high to me. Anything less than 35-40 MPG gets expensive when you drive a lot of miles and have to spend what is now higher gas prices. What happens when the cost of gas goes really high? Most people will want better mileage than those Toyotas provide.

 

 

yes indeed, those numbers arent high. Interestingly, consumer report said "corolla LE gets budget-pleasing 28.6 mpg", but to me, it sounds like "corolla's a lemon".

yes indeed, those numbers arent high. Interestingly, consumer report said "corolla LE gets budget-pleasing 28.6 mpg", but to me, it sounds like "corolla's a lemon".

It depends on whose "budget" they are talking about - certainly not mine or the average consumer.

 

 

maybe the consumer report driver drove a corolla with the ECU that gives lower mileage. Or, he was paid to drive such that the mileage was low. Or, he picked the winter gas which reduces the mileage even more. Or, ...

maybe the consumer report driver drove a corolla with the ECU that gives lower mileage. Or, he was paid to drive such that the mileage was low. Or, he picked the winter gas which reduces the mileage even more. Or, ...

Maybe they just make up the numbers and use them to sway the consumer to buy the model?

 

 

maybe he's me! muhahaha.. lol jk jk

I think there are too many variables in any mileage test. Drivers are different, conditions are different, cars are never totally identical.

The milage reported by CR always sounds much lower than the EPA. I think the testers drive the cars as hard as they can.

BTW, Bikeman, using 20W50 oil, especially in corolla is insane. I like heavier oils myself and sometimes use 5W40 and 15W40 oils (not in corolla though), but 20W50 in modern car is just crazy. Last cars designed for 20W50 were made back in 70s (i guess). You are not only burning more fuel but possibly increasing engine wear in cold and startup.

The milage reported by CR always sounds much lower than the EPA. I think the testers drive the cars as hard as they can.

BTW, Bikeman, using 20W50 oil, especially in corolla is insane. I like heavier oils myself and sometimes use 5W40 and 15W40 oils (not in corolla though), but 20W50 in modern car is just crazy. Last cars designed for 20W50 were made back in 70s (i guess). You are not only burning more fuel but possibly increasing engine wear in cold and startup.

It does not take long for my car to warm up and I drive 50 miles at 80 MPH. That puts a lot of heat on the engine and definitely heats up the oil. It gets thinner as it heats up and 20W50 is not an unreasonable oil to use, under those driving conditions.

 

 

The milage reported by CR always sounds much lower than the EPA. I think the testers drive the cars as hard as they can.

BTW, Bikeman, using 20W50 oil, especially in corolla is insane. I like heavier oils myself and sometimes use 5W40 and 15W40 oils (not in corolla though), but 20W50 in modern car is just crazy. Last cars designed for 20W50 were made back in 70s (i guess). You are not only burning more fuel but possibly increasing engine wear in cold and startup.

It does not take long for my car to warm up and I drive 50 miles at 80 MPH. That puts a lot of heat on the engine and definitely heats up the oil. It gets thinner as it heats up and 20W50 is not an unreasonable oil to use, under those driving conditions.

 

when you use an oil that thick it can do bad things like starve the valve train of lubrication. even tho the car may warm up fast that oil is just too thick, yes you have more oil pressure but at the cost of volume since the oil pump cant push 50W oil through the oiling system as fast as it can push 30W oil. ive seen people spin bearings from using too thick of oil, they had awesome oil pressure and thought it was ok and then TICK TICK TICK TICK they had spun a bearing in the engine because the thick oil couldnt flow enough to keep things lubricated. use 10W-30 in your car and you'll be doing more good than running 20W-50.

 

the hot thing is a little misguided. oil viscosity is graded at 210F (or was it 180F?), its how fast a certain volume flows through a certain sized opening on its own. 20W is the oils free viscosity at 210F, free meaning its sloshing around in the crank case. the 50 is its viscosity at temprature when its being pushed between bearing surfaces and through oil passages. the little wax beads elonagate and cause a thickening effect that doesnt happen when its just sloshing about in the crank case.

The milage reported by CR always sounds much lower than the EPA. I think the testers drive the cars as hard as they can.

BTW, Bikeman, using 20W50 oil, especially in corolla is insane. I like heavier oils myself and sometimes use 5W40 and 15W40 oils (not in corolla though), but 20W50 in modern car is just crazy. Last cars designed for 20W50 were made back in 70s (i guess). You are not only burning more fuel but possibly increasing engine wear in cold and startup.

It does not take long for my car to warm up and I drive 50 miles at 80 MPH. That puts a lot of heat on the engine and definitely heats up the oil. It gets thinner as it heats up and 20W50 is not an unreasonable oil to use, under those driving conditions.

 

when you use an oil that thick it can do bad things like starve the valve train of lubrication. even tho the car may warm up fast that oil is just too thick, yes you have more oil pressure but at the cost of volume since the oil pump cant push 50W oil through the oiling system as fast as it can push 30W oil. ive seen people spin bearings from using too thick of oil, they had awesome oil pressure and thought it was ok and then TICK TICK TICK TICK they had spun a bearing in the engine because the thick oil couldnt flow enough to keep things lubricated. use 10W-30 in your car and you'll be doing more good than running 20W-50.

 

the hot thing is a little misguided. oil viscosity is graded at 210F (or was it 180F?), its how fast a certain volume flows through a certain sized opening on its own. 20W is the oils free viscosity at 210F, free meaning its sloshing around in the crank case. the 50 is its viscosity at temprature when its being pushed between bearing surfaces and through oil passages. the little wax beads elonagate and cause a thickening effect that doesnt happen when its just sloshing about in the crank case.

I'll take your advice and switch to a lighter weight oil and hope that improves my engine performance. I will have to wait until I get better weather here, since it is the rainy season and I do my own oil changes. Will I notice any performance gains or better mileage? I do 100 miles a day and it won't be long until I need a regular interval scheduled change for the oil anyway. I will let you know how it goes.

 

 

you COULD pickup a couple mpg. i cant really say for sure tho.

to put things into a smaller scale, if you have a lawn mower fill it with 30W oil (like it should be) and run it, mow some grass. then change it to 50W oil and do the same. on this small scale you can really see the difference between how the 2 affect the engines performance.

The milage reported by CR always sounds much lower than the EPA. I think the testers drive the cars as hard as they can.

BTW, Bikeman, using 20W50 oil, especially in corolla is insane. I like heavier oils myself and sometimes use 5W40 and 15W40 oils (not in corolla though), but 20W50 in modern car is just crazy. Last cars designed for 20W50 were made back in 70s (i guess). You are not only burning more fuel but possibly increasing engine wear in cold and startup.

It does not take long for my car to warm up and I drive 50 miles at 80 MPH. That puts a lot of heat on the engine and definitely heats up the oil. It gets thinner as it heats up and 20W50 is not an unreasonable oil to use, under those driving conditions.

 

With this type of driving, the oil temp should be fine, unless you overload the car, tow, or go uphill all the time. But even then 5W40, or 10W40 would be plenty of reserve, remember totota specifies 5W30. I would be more worried about ATF temp, as I clocked up to 250F in corolla driving 85 MPH with AC in hot summer (90F ambient). The ATF was dark when changed at 30000 miles. I will put ATF cooler in as soon as the drivetrain waranty expires.

I have formed 2 hypotheses regarding this topic from reading many forums and tons of postings. Please note I have not had the opportunity to validate either one yet.

First a little background:

-2005 Corolla S

-Bought new April 2005

-Manual Transmission

-Wife's car

-New England/Upstate NY weather patterns

-30sec or less warm-up times

This is our trip car, so we take it for 500mile trips between MA and NY. With a fill-up at either end, checking MPG, every time; Best = 42, Worst = 32. Best was during moderate to warm temps without A/C. Worst was winter driving with snow.

During this past winter, now hopefully coming to an end, I have seen very inconsistant MPG's ranging from 38 to 32. This has bothered me because nothing from the driver/maintenance end has changed.

Hypothesis 1:

The engine in the Corolla is very tiny and the large engine compartment provides lots of space for airflow. Is it possible in winter weather the engine does not reach proper operating temperatures due to too much cooling/ventilation?

Hypothesis 2:

As I have read, and makes sense, the colder the air intake the more fuel required for proper engine combustion. If one were to alter to a warm air intake, reroute intake to inside engine compartment, would this help MPG? Year round? In winter season?

Thoughts?

Winter time is a hard time to gage fuel economy. For one, any time you drive in snow, slush, rain, ect, it is resistance on the tires. Anytime you have a hard wind, you can get lousy fuel economy. It can also come down to winter fuel formula's.

The EPA numbers can be had, but only when the roads are dry and the wind isn't moving much. Also summer fuel has less aditives and you should get better fuel economy on that.

We've been averaging 32-43MPG, but latly, it's been all in town miles. I'm sure I can get that 40+ again this sumemr when I got on a longer trip.

I know your never suppost to go by the fuel gage to figure out fuel economy, but even this last tank now that the roads are clear, I can tell when I'm getting good fuel economy. When I get over 100 miles per 1/4 mark on the gage, then we are doing good. On bad tanks, it reaches about 85-90 miles per 1/4 mark. I use math to figure out what it really is, but I can tell on the gage and tripomitor if we are doing good or not. I wouldn't be surprized if this tank is more like 36-38MPG. We went spent some more time on the HWY this tank.

One thing that bothers me about cars sold in US that they dont display instant MPG, except for a couple of hybrid cars. Many or not most cars in Europe have it standard. If we had that instant feedback, people would learn quicly to save tons of fuel. A test drive while buying a new car would have a different meaning.

Agree!

I have seen this technology on many high $ vehicles (i.e. - Acura MDX, Corvette, Chevy Avalanche).

I'm in the process of researching OBD-II to laptop devices so I can monitor this and, hopefully , any other data the ECU can provide. Then maybe I'll attempt to validate one of my hypotheses mentioned earlier.

Very interesting....Yet another innovative technological accomplishment that never made it into the main stream. But, it kinda begins to validate my hypothesis on a WAI.

Warmer air = more combustible = less fuel required

Now.....Please correct me if I'm wrong but in today’s cars timing is controlled by the ECU. Therefore, if you were to increase the intake air temp altering the point of detonation the cars ECU should automatically adjust.

Like what a knock-sensor does to adjust for different fuel octanes.