I am one of the original posters of the rough idle on cold startup. My dealership and I have tried many different approaches to fix this problem with little or no success. Let me start by saying the service has been above my expectations. I feel sorry for everyone with poor service. I highly value good service and drive 110 miles each way to get it! And my wife says I'm obsessive :-)

1. Picked up car 8/6/00

2. Had coolant sensor replaced to cure rough idle (12/2001).
.....a. No fault codes found by dealer, but they had 1 other car with a worse case then mine, so they gave it a try.
.....b. This has been the best fix so far; I had very little problems depending on Gas Brand & Octane, but still
.........some roughness.

3. Dealer suggests a change of fuel octane to cure the remaining problems.
.....a. Extensive "self imposed" testing of different brands and different octane's. Each "new" brand/octane for 2 full
.........tanks followed by 1 tank of BP 93oct. for a "base line". 2,500k a month gets a lot of testing done quickly!!!
.....b. Best results with BP 93oct. and Sunoco 94 ultra. BP is closer to house so this has been my main gas.

4. Problem has been getting worse. 8/2001 dealer looks at car again, still no fault codes but agrees there is a problem. AOA rep. suggests changing mass airflow sensor. 9/2001 mass airflow sensors replaced. Did NOT help!!

5. Dealer at a loss. No help from AOA rep. Dealer knows I'm part of AW; suggest I come here for answers/suggestions!

I know some one suggested a recoding of ECU, something to do with an update from 2000 coding to 2001. Mine is an early 2001 so I don't know it this could work but I need more information. My service manager said he hadn't heard of this and needs more details to know what to do.

Another thought I had was that maybe the coolant sensor went bad again...any thoughts?

Thank you in advance!!!!

Jeff Booser 2.7
Ming Blue/Vanilla

 

OK...so preview didn't help for lineing up bullets...sorry

 

1. Is the roughness the same with the climate control on and off? Remmeber, the computer will adjust the idle if it thinks the A/C is on.

2. Have they checked the old fashion way for vacuum leaks? Like spraying something on the vacuum lines and seeing if the idle changes?

 

What should I do if it affects it? My climate control is always on!

 

If you don't shut off your A/C once in a while (like every time you're parking!), you're going to get moisture staying in the system too long and you will get mold.

 

we don't go "Parking" anymore :-P

"NO WAY DEAR...NOT IN THE AUDI!!!" he said.

I thought replacing the filter took care of this. If not, what & how often should I do something else???

Booser 2.7
Ming Blue/Vanilla

 

It is just moisture in the system. wait for a nice dry day, then run it on "econ"

 

That way the residual cooled air in the system is blown out into the car. Using this method, I've never had a problem with mold. This is not a filter issue. Wurth makes a special product just for doing this disinfect, you can get it at carcareonline.com. Some have just emptied a whole can of Lysol into their system with good results.

When we bought my wife a used Merc, it was a major mold factory. Apparently, the prev owners didn't know that it was possible to not run the A/C all the time (in their defense, carmakers make the on position the default these days). The service dept had to do a major disinfect, and now all is well.

 

ty

 

as dopey as this is going to sound,see if the dealer will replace the boost pressure and or the intake temp sensor.reason being,these sensors measure manifold air pressure and the baro sensor in the computer measures air pressure.if these signals don't correlate the car will run all kinds of weird ways.i had a tt drive me nuts because whenever it wanted to it wouldn't start,but always started for me until 4 days later i finally got it not to start and it turned out the boost sensor burped and made the car think it was in denver[high elevation/thin air,computer cut fuel]even though i was at sea level.replacing the sensor fixed it and never any check engine light,in your case i would either look at the boost sensor or intake air temp sensor,if no air leaks ,vacuum leaks,etc. exist let them look down the route of incorrect air temp readings.note; air temp and coolant temp #'s should be within 5 degress of each other cold[key on engine off]