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View Full Version : Stalls When Warm Outside



JimH79
04-22-2013, 05:45 PM
First, let me say I am not an Audi expert nor am I an expert mechanic. I have a 2001 Audi B5 A4 that seems to start and run fine until it has been driven 15 minutes or so and is > 80 degrees outside. The car will stall when I let off the gas pedal and then has to sit for at least 3 - 5 minutes and then will start again. The longer the car sits the longer it will run before dying again, which tells me the more it cools off the longer it runs. The car is not running hot it is running in the normal temperature range. I am hoping that someone has experienced this problem and can help me. PLEASE HELP!!!!!!!!

contrldsub
04-22-2013, 05:54 PM
intake air temp sensor might be faulty. it really could be many things to be honest. is the engine light on?

JimH79
04-22-2013, 08:33 PM
Engine Light is on... I've been doing some research on the internet and it seems like the most common answer is that it would be running really lean on fuel. I don't know if it may be the fuel pump but I will check the intake air temp sensor as well. Thanks so much. Any other advice would be appreciated.

thenj3
04-22-2013, 08:38 PM
Find out what code is tripping the check engine light. That will be your answer.

TJN0923
04-22-2013, 09:53 PM
Check the ecu box for blown relays. My car did something similar for the longest time.My car would do a cold start every time. Yet would never turn on when it was hot or if I would stop and turn it back on real quick. My mechanic was able to help me out with it. Definitely too tricky for me.

contrldsub
04-23-2013, 11:29 AM
Find out what code is tripping the check engine light. That will be your answer.

^^^^^^^^^^^^

woolveren
04-24-2013, 06:25 AM
intake air temp sensor might be faulty. it really could be many things to be honest. is the engine light on?

This said, a bad intake air temp sensor can still be within range of normal limits and not set off a trouble code even though it is providing the wrong temp signal to the computer.

contrldsub
04-24-2013, 06:47 AM
This said, a bad intake air temp sensor can still be within range of normal limits and not set off a trouble code even though it is providing the wrong temp signal to the computer.

typically a faulty temp sensor of any sort will send a signal of -44 deg F when it is shorted internally. a fualty temp sensor rarely still functions at all and just sends a fixed signal to the PCM. i do agree tho that it might not cause a code to pop up because it COULD be -44deg. however the PCM does cross reference signals and on a cold start the PCM will look at ECT and IAT and on our cars ambient air temp. if one is too far out from the others it can pop a code. usually something like an implausable signal or something like that.

walky_talky20
04-24-2013, 06:47 AM
Intake Air temp has fiarly little to do with afr at idle. Coolant temp has much more to do with it. My guess is CTS.

With any luck the codes will tell the story.For the laziest of diagnostic procedures you can just unplug the IAT and see if still does it. The car will run fine without it.

woolveren
04-24-2013, 10:42 AM
Intake Air temp has fiarly little to do with afr at idle. Coolant temp has much more to do with it. My guess is CTS.



Or may be a weak O2 sensor?

The O2 sensor is ignored when the car is cold so the car runs fine. Once it warms up, the computer starts accepting readings from the O2 sensor and makes fuel adjustments. If the sensor is incorrect or faulty, the computer will make incorrect adjustments to the fuel map and the car will run badly.

walky_talky20
04-24-2013, 11:06 AM
Interesting theory. And the 2001 1.8T has a wideband o2 sensor which does have significant authority for changes in fuel quantity. It wouldn't be my first guess, but it would be something to look at.