2001 Corolla Fails To Start, P0171, Possible Fuel Leak?
by johnmcclure, March 26, 2012
Hi folks,
my 2001 Corolla (automatic), about 120,000 mi, has an interesting problem.
It starts up fine in the morning, or anytime it's been sitting for a while (30+ minutes).
If you shut it off, and start again within a couple minutes, it starts up again fine.
but if it is off for more than 5 but less than 30 minutes, it fails like this:
The engine turns over, and catches, sputters, and dies. there is a sound like maybe not all 4 cylinders firing.
The only solution is to wait about half an hour; then it always starts right up.
The CEL has been in for a while: p0171 (system too lean bank 1).
About a year ago, I had a loss of power on acceleration and the same p0171 code; after researching on this forum and others, I replaced the MAF sensor, and the problem was solved.
I have on occasion recieved a CEL for "evap emissions leak (small)", which at the time I attributed to a loose gas cap.
My theory is that there is a small leak in the fuel line, upstream of the engine but downstream of the fuel pump; and when the car is warm some sort of vapor-lock occurs; that is why it starts once it's cooled off. And that the leak is small, which is why it will start if the engine is only off for a couple minutes - the pressure is not yet lost.
I know nothing about the fuel system - a simple block diagram would be helpful to see - but I want to do all the work I can so I don't go broke being ripped off by the local auto shops (Norfolk, VA).
Has anyone seen this before, or have any other ideas, or troubleshooting that could help me narrow down the problem?
PS I replaced the gas cap; it made no difference (as I expected; but worth a try, right?)
Thank you for your help and advice.
John
Bad_dude
Starts with the easy stuffs first. Check the gas cap to see if it works correctly. Clean the MAF. Then if those fail, do a fuel pressure test. Check the O2 sensor bank 1.
Could be the injectors leaking fuel into the combustion chambers and fouling the plugs. Short duration time doesn't give it enough time to leak enough to cause problems. If you wait much longer, gives it a chance to evaporate.
Try repeating it and get it to its failure mode. Push the accelerator down to the floor (car in park) while you start up and run the car - note engine will race when you do this, no worries. See if it dies when you do that. If it dies, you likely have a fuel/ignition/ECM issue - if it doesn't die, likely something to do with the fuel system. Pushing the accelerator to the floor when you start the car is the way to clear flooded engines. Not usually see with fuel injected cars anymore, but can happen from time to time.
I took it to the dealer and they said I need to replace my IAC valve. They quoted me about $650 installed, but I see the part is available for around $230. I've decided to order the Torx Plux 5-point IP20 discussed on this forum, and attempt to replace it myself.
But before I do, I need to be certain the dealer isn't jerking me around.
I am distrustful of them, because if I understand correctly, a failed-shut IAC valve would prevent you from starting at all, whereas I can start just fine if cold. My failure is only if the car has been off for more than 5 minutes, but not long enough to cool down.
Does the IAC explain this? Could the IAC simply be dirty? The dealer said cleaning it will not solve my problem, it must be replaced.
what do you guys think? I have no idea what tests the dealer did, but the IAC valve was not removed during their diagnosis as far as I can tell. Should I trust them and just replace it, or investigate further? Also, could the IAC valve explain my P0171 (too lean), or is that a separate issue altogether?
Amplifying information:
When starting cold, I have to crank it at least twice to start it. That is a newer development and seems to be getting worse.
Up to today, I hadn't heard of an Idle Air Control valve. But I have heard of dealers who can't wait to take us to the cleaners.
And speaking of cleaners, I'd do this job myself.
Took the '98 to the stealership's service department for the IAC valve back in 2006, that and a system cleanout set me back about $550 if memory serves. The IAC valve was stuck shut after I attempted to clean it and the idle wouldn't drop from 1500. Apparently this oft overlooked maintenance interval caused the IACs to fail over time.
You'll either have to pinch off the coolant hoses to the IAC or drain the radiator a little if you do this yourself. The service center had it all done in about an hour.
