1998 Audi A4 Stalling when hot.

whiz · Posted at Fri Sep 19, 2008 11:35 pm

Engine Performance problem
1998 Audi A4 4 cyl All Wheel Drive Manual 203000 miles

My Audi A4 1.8 Turbo Quattro has an odd issue.

When cold, it starts and runs fine. After a drive where it gets to temperature, if I let it sit for a few minutes, it will stall randomly while driving.

When moving off at the lights, or if I hit a bump and it is warm, the engine loses power or stalls. It only does it when it's warm.

I have replaced the MAF, Ignition control module and I have stripped back the wires to check for issues with the wiring harness. Nothing so far.

The vag com reports that MAF sensor readings are out of limits and this error happens instantly the engine stumbles.

It's definately a heat related issue, but for the life of me I can't understand where it is.

KHLow2008 · Posted at Sat Sep 20, 2008 5:32 am

Hi whiz,

I believe you are correct in saying it is heat related but not in the sense that you mean.

It should be a loose connection somewhere and when heated up it provides higher resistance and inaccurate data transfer. Since the MAF is showing an error, I would suggest checking the connections that are related to this item. It might be due to contaminations, oxidation, dirt etc.

whiz · Posted at Sat Sep 20, 2008 7:27 pm

I've already been over the connections to the MAF and have inspected the plug for any sort of issue. It looks fine as do the male connections on the MAF.

It's going to get to the point where I heat things up with a hair dryer to see which bit causes the issue. It's such a dumb problem but it makes the car almost impossible to drive safely.
The warmer weather can bring the car to the temperature where it will malfunction from sitting in the sun.

KHLow2008 · Posted at Sat Sep 20, 2008 8:12 pm

Hi Whiz,

I aready mentioned about the resistance part so I don't think using a heater can get the problem to surface.

It should be due to heat buildup caused by high electrical resistance.

You mentioned going over bumps would affect/contribute to the problem. Check for any loose or not properly tightened components with wire connectors. Loose/bad grounding straps are possibilites too.

Check the Intake Air Temperature and Engine Coolant Temperature sensor connectors.