Idles But Dies Out When You Give It Gas
Posted 07 December 2009 - 02:58 AM
Posted 07 December 2009 - 07:39 AM
This Corolla has a fuel filter in the gas tank - part of the fuel tank assembly. But generally does not need to be replaced unless you know there was some contamination poured into the tank (i.e., accidentally filled it with diesel). The system uses a returnless fuel system, so fuel will not spray out as quickly as other fuel injection systems.
Vacuum leak would cause all sorts of problems. Depending on what other leaks are in there - could be causing the off idle stumbling, engine hesitation, as the air/fuel mix will be off. Try resetting the ECM first, clean the IAT and MAF sensors (on the airbox), give the throttle body a good cleaning + fix the vacuum leak, double check that the plug gap is 0.044", PCV is clear and all hoses are running to where they need to go.
When you test it - accelerate with the car in park, see if there is a fuel/spark issue. Then do the same thing and slowly accelerate in gear - see if it cuts out again.
Posted 07 December 2009 - 09:31 AM
Posted 08 December 2009 - 01:50 PM
Posted 08 December 2009 - 06:31 PM
Does the engine cut out when you try and race the engine in park? Checked to make sure you get good spark on all the igniters?
Posted 09 December 2009 - 03:34 PM
Posted 09 December 2009 - 04:57 PM
Anyway you can post a sound clip - just so we can hear how it dies? Have you tried gunning the throttle in park, slowing accelerating in park - to see if it stumbles at a particular RPM or throttle position? Sounds like you will need to throw a data logger to see what the sensors are reporting back to the ECM. Was there any CELs before you starting working on the car, even old ones?
Posted 09 December 2009 - 05:02 PM
Posted 09 December 2009 - 05:03 PM
just when you give it gas it dies?
In truth, you're giving it air, not gas, when working the 'gas' pedal. The system is supposed to respond to the additional air with additional fuel, based on what it detects from the MAF sensor and in relation to what the O2 sensors report.
Part of the problem with the vacuum leak is that it's invalidating MAF data in the first place. Opening the throttle then changes the input air from post-MAF sensor to pre-MAF sensor because the throttle plate restriction at idle means that a lot of the air it gets at idle is bypassing the MAF sensor. The system then sees a gigantic change in mass airflow, more than is normal without the post-MAF leak, so it dumps much more fuel.
I would experiment to see if this problem still occurs with the MAF sensor disconnected (just remove the connector from the sensor and leave it physically installed so you don't allow unfiltered air into the system). It may run oddly as it will have no MAF data, but then operating the throttle may give different results. Maybe that will prove nothing, but it might give us some insight.
Note that the CEL should come on with the MAF disconnected. Once reconnected, the light should go out on its own after a couple of driving cycles. I've found on my own '01 LE that I can do similar operations, and after reconnecting the sensor I just need to drive about a mile, then shut off the engine and restart it-- the light goes out as if nothing had ever happened.
Edited by AlaricD, 10 December 2009 - 09:46 AM.