I have a 01 GLE that I bought and resurected recently. When I did buy it it had a P0171 code that I did the search on and found that in most cases it is the MAF. I cleaned the hell out of it, reset the CEL and started driving it. Still no code return but it is stalling every once in a while if you sit and idle for a bit. I was going to say scanner but I am going to correct myself and say code reader does not show anything but would you think that I should just change the MAF? I don't really like to throw parts at a problem but this seems to be the most common failure on these. Someone correct me if I am wrong or looking at it the wrong way.

The car has 180,000 kilometers on it and all maintenance is up to date.

 

I wouldn't suspect MAF. If I remember correctly you can unplug the MAF and the car should still run, mind you it'll run horribly, but it'll run.

Is it a clean stall or does it grumble and try to maintain idle before finally giving up?

 

If you have a scanner you can monitor the MAF readings at idle to see if it fluctuates. It should not fluctuate. If you see it fluctuate at the point when the car stalls at idle then it is your MAF.

 

I had that exact problem: MAF Replaced, Still No Improvement. I'm Stumped.

It needed a new MAF, and the ECM needed to be reprogrammed by the stealership. But it all worked out.

 

Ok so now it gets interesting. As I said I cleaned it cleared the code and the code has not come back and I have driven about 120 miles. It stalls on occasion only when warm but the idle drops to about 500 rpm and will be that low but seems as if it is hunting. Sometimes whan it is hunting it stalls and other times it is fine and maintains a low idle and then it seems to find itself and pick up slightly. Still no code set.

I am about to go for the Canadian Thanksgiving long weekend on a 200 mile road trip one way, so I will see how it performs and what kind of mileage I am getting, city driving for the first week of registered ownership is not giving me a real feel for this problem. I will report back when I return on Monday afternoon.

Thanks all.

 

Clean your Idle Air Control Valve; cleaning MAF is not going to fix your stalling at idle.

 

I would start with the IACV. If it goes bad it can fry your ECM.

 

If it fries your ecm will your car not start? Or will you notice if it fried it?( not trying to hack thread)

 

I was reading that about the ECM and I will get into the IAC this weekend. I would think that a new IAC is what is called for and not just a cleaning of the existing unit? New to this platform and have not had a good chance to dig deep with the search on the board.

I have kicked the P0440 code again and I noticed that the gas filler neck is corroded so I will clean that up as I do not want to do a canister but will if required. I just want this idle problem fixed and then a LED upgrade for the interior as the lighting sucks!!!

 

I have been doing more reading on this problem and paying attention to the car and have noticed that the gas milage kind of sucks. That would really go hand in hand with the code and the stalling. The reading showed me that the MAF could be failing but not throwing the code sitting on the edge so to speak and the Long Term Fuel Trims being too high. When the new MAF is installed it is recommended to clear the LTF. Well since I have cleaned it to try and get it better why would I not do the simple procedure to clear the LTF and see where it goes. I have done it and it already seems to idle better but I have not had a chance to get it out and test it. I will report back.

 

I forgot to mention that I found every clamp loose on the air intake system when I did the clear procedure. I have since had the car out and it runs and idles so much better and it is by feel. It had a stumble in the idle or low rpm area and that is now gone and the car seems to have more power.

I wish I had a scanner and not just a code reader so I can see live data, I will investigate what others have and go there it is not as if I only have this one vehicle so it can be used in the fleet.