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Engine Stumbling Or Transmission Slipping

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#1 grim


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Posted 08 August 2012 - 12:01 PM

Hello everyone! 1999 Corolla VE 3spd automatic: I've been having issues with P0441 and P0446 codes and I'm due for inspection, so I've been messing with a lot of stuff lately :(
I'll try to keep from making this sound more complicated than it already is. I blew compressed air through the line behind the vsv in the engine compartment (engine off) to blow some debris out of the vapor canister lines, code went away and had a ready signal (lasted about 5 days) till I was almost to the inspection station... figures. The hoses are all original so I went ahead and replaced the booster brake hose and the hoses in the engine compartment to and from the VSV and the gas cap for good measure. The hoses were certainly leaking and noticed some difference in performance, but not all good. Now when I go to accelerate, the engine seems to stutter or stumble, as if I'm pumping the pedal very quickly but intermitently. It's not constant though, and is fairly drivable, but theres certainly a problem. I figure whatever is wrong was being masked by the vacuum leaks, though it could just be a coincidence. I noticed that it wont do this in park or neutral though, so I wonder if the transmission may be slipping.

So far, all of my guesses are leading to expensive parts that there's simply no way I can afford right now. I'm hoping someone can help me narrow this down to less expensive parts, or at least of few less likely ones.

Vapor canister: may still need replacing, but I don't think it is causing this problem.
Fuel pump: Maybe the system is putting the proper vacuum to the tank now and the extra load made a pump on the way out a lot more obvious?
Transmission: It's just too hard to tell if the engine is fluctuating or the transmission is slipping, but it seems fine in park and nuetral, so transmission could be an issue I guess. I would expect it to cause the engine to rev higher, not lower though.
MAP sensor: It seems to be working fine, and I have no really good reason to suspect it, but I've seen them cause stranger problems.

I had reset the check engine light, so I'm not seeing any codes yet ( my scan gauge cant read pending codes) but while I was accelerating up a hill, engine stumbling badly the whole way, the engine light started blinking till I got up the hill and then went out, haven't seen that before.

#2 fishexpo101


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Posted 08 August 2012 - 12:28 PM

Flashing CEL is a sure sign of misfiring. Could be caused by a number of things, but since you recently worked on the EVAP system - cause is likely related to those fixes.

Most of the time, EVAP codes just effect emissions, on an 8th gen Corolla - you are not alone. I've been battling them for some time as well - funny thing is, it only happens right before the emission's check month for me - the other 23 months, the car runs flawlessly, no CEL!

For codes:
P0441 - Evaporative Emission Control System Incorrect Purge Flow
P0446 - Evaporative Emission Control System Vent Control Circuit Malfunction

Most likely, the cause is a faulty VSV on the body of the vapor canister. If you shop around - will run between $60-$90 for that valve. From there, any number of hoses and valves on and around the tank.

The vapor canister itself almost never goes bad, unless you have a habit of topping off the gas tank (bad habit, can easily flood the canister with raw fuel). If you are really pressed for time, an EVAP "smoke" check can quickly locate the problem area(s). I was getting the same codes, already changed the VSV and a number of hoses, but in my case it turned out to be a bad cut-off valve on the top of the gas tank. A $30 part but you have to drop the tank to get to it.

The driveability issues have me more concerned - you generally will not see those unless you have a completely blocked EVAP system. EVAP system is just designed to hold fuel vapors, later to be pulled into the engine via vacuum, to be burned off. It is possible that the compressed air trick forced more debris into the system than push out.

That it doesn't seem to show up in Park or Neutral makes sense - as that is when you generally will see more consistent amount of vacuum (depending on throttle position as well). The stumbling could be from a completely separate issue. To be sure - double check the plugs, check for vacuum leaks under the hood, etc. The fuel system is a returnless design, so it shouldn't be too affected by what you've done. A dying fuel pump could cause the driveability issue you are seeing, but the EVAP codes.

Sounds like there might be more than one thing acting up on the car - need to eliminate as many of the easy/free stuff to check/do - to help point you in the right direction.

#3 grim


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Posted 08 August 2012 - 05:53 PM

It seems bosch doesn't make anything well these days.i had replaced the plugs with fusion ir's and their ultra premium wire set maybe a couple of years ago now. I still had the original denso worn out plugs, they made the stumbling go away, the wire set has shocked me in the past, but I modified them to work as the old boot had melted on the original set. What a coincidence... Going to order the right plugs this time!

#4 grim


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Posted 11 August 2012 - 05:16 PM

Though the car is running quite a bit better, the cel lit up again, same as usual, P0441. I was under the impression the vsv on the canister was part of the canister itself and required the entire unit, if the part is indeed replaceable, can you point me to a part number?

#5 dom


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Posted 12 August 2012 - 01:15 AM

Vacuum switching valve, Toyota part # 25860-22020.


Dorman # 911-603 is said here to be a replacement for Toyota # 25860-22020, but is not listed for a 1999 Corolla on Dorman's site...


Available for $32.02 (see photo).


#6 grim


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Posted 12 August 2012 - 08:58 PM

That looks like the one under the hood by the air filter. I've tested it and it checks out fine, put vacuum to it, ran 9volts, heard click and watched vacuum bleed off.

I haven't done that with the ones on the canister yet, but those are what I am assuming are the problem, are they the same part?

Edit: Sites like toyotapartszone had parts diagrams that made it pretty easy to find this stuff, but looks like they stopped offering them for this car, anyone know of another site that has those diagrams? Google isn't helping me find anything but dead links to sites like toyatapartszone.

Edited by grim, 13 August 2012 - 08:37 AM.

#7 grim


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Posted 17 August 2012 - 09:48 AM

Found this site with most of the diagrams if anyone is interested: http://www.villagetoyotaparts.com/
So I ordered 1 of the valves 4 plugs and a fuel filter, hope I only need 1 valve, part being 90080-91240 for $25.98 at toyotapartzone