MY MAXIMA STALLS

[spiaggia]

I really need help and suggestions on how to stop the stalling of my 2002 maxima GLE engine.

For over a year now after driving for between 30 mins and 1 hour, my engine stalls and no matter how hard i step on the gas it simply would refuse to move. I have also noticed backfiring.

This situation persists except i off the engine and start again.

I do not know if this can be from the coil or if the maxima has a condenser but i need suggestions please

[loystock]

You have this problem for over a year and you haven't done anything, yet? Backfiring or engine hesitation/stumbling can stress out other engine components and sensors.

Is the CEL ON? Have you gone to Autozone and the like for a free OBD II scan? Get a printout, if possible.

The backfiring may be due to very lean air-fuel mixture (vacuum leak or low fuel pressure). The stalling/backfiring can also be caused by ignition issue (bad timing, dirty/failing plug(s)/coil(s); faulty injector; dirty/failing MAF sensor. The car may also have an exhaust leak which manifest itself when the engine it hot.

[ERUOTANEN]

So does mine (2000 model), and I have been thru a lot with it lately. I have had the ECM rebuilt, new MAF, new crankshaft and camshaft sensors, diagnostics run on it by dealership who gave up on it. They checked the trouble codes and those revealed nothing to them. My last test was to check alternator and battery and thru my testing both of those are fine.
My symptoms now are: Once the car gets warmed up and runs for 10 to 20 minutes, it simply quits running, either at idle or at speed. It may "cough" once or twice and then just quit. SES (CEL) comes on and it may or may not go out. Sometimes the car will restart and run for a little while longer until it quits all together. Usually after a 30 minute wait, it will restart and run again for another 10 -20 minutes before it stops again.
My latest thoughts from other people with simiar problems is that the catalytic converter could be stopping up when after it heats up, and opens up enough to run after it cools down some- for a while before the cycle starts again. Loystock has been very helpful.

[spiaggia]

I thank you guys for the suggestions and think am actually more confused now. it seems that there are so many things that could be wrong to cause the conditions i have at the moment. Scanning hasnt proved helpful and have even gone ahead to replace most sensors.
I think i will start with catalytic converter and then move down to my exhaust for leakage.

[loystock]

You mentioned that scanning was not helpful and replaced most sensors. Please be specific so we can help you. Was there any trouble code? Which sensors were replaced. If your car is well maintained, there is less likelihood of 'cat failure. But it's possible that you have had bad MAF/O2 sensor for an extended period of time. Such failure can cause rich air-fuel mixture, with unburned fuel getting into the 'cat' and igniting, damaging it beyond repair.

There are so many reasons for an engine to stall and may be hard to start when warm. When the engine is cold, the ECU runs in open-loop mode (some engine sensors like O2 are not being used). The Coolant Temp Sensor may be defective preventing your ECU from reaching closed-loop mode. It's possible that CTS is good, ECU goes in closed-loop but a component like the front O2 sensor is defective, causing erratic signal to ECU. There is also a possibility of heat-sensitive crankshaft/camshaft sensor. So it is very important to get and record the trouble code.