jzkbbi

My 2000 A8 has 118k miles. When starting cold in the morning, the RPMs surge up, then drop down killing the engine or almost killing it. Sometimes I have to gently put my foot on the throttle to keep it running. Once it starts it just surges up, then down then up. Sounds like I am racing the engine, but I am doing nothing. After 4 minutes, all is fine. When I start the car at lunch or to go home from work, no problem. Perhaps a trace of this, but nothing like the morning.

Is some sensor failing or something like that?

Thanks!!!!!

aduggs

This happened to me not long ago. Usually is a dirty throttle body.

See other post: https://www.audiworld.com/forums/sho...rpm+fluctuates

Be sure to reset the throttle body through vag-com.
Follow this procedure: https://forums.audiworld.com/archive...t-1752181.html

Alex

jzkbbi

Thanks!

Where is the throttle body?

aduggs

It's on the backside of the engine near the top middle. You can follow the air intake duct (this will have to be removed to access the throttle body). Very simple, just need to loosed a couple hose clamps, disconnect the duct from the engine, and then rotate the duct out of the way.

You can pick up throttle body cleaner from any auto parts place. Just need a rag or something to wipe away the dirt.

silverd2

To further clarify: The engine is that big, hot, vibrating thing behind the really big door (hood) on the front of the car

Friendly advice (seriously!): Sorry, but if you had to ask that question, save yourself some misery and likely self inflicted added damage...have someone else check it out.

Asiparks

my wife has been having an identical problem with her '00, only happens on the first start of the day, but if it kills the engine, then the battery symbol lights in the dash, does yours do that, or is that something else happening ?
The battery is good BTW....

jzkbbi

I cleaned the throttle body a bit on Sunday. Of course, I couldn't really find out the results until I tried to start it for a couple of mornings.

It is much improved as the engine no longer dies. It does rev up a couple of times before settling in at idle, but I no longer have to restart a bunch of times or try to throttle up a cold engine.

silverd2, thanks for the insult. As an engineer I am very capable of learning to fix something with which I am not familiar, but it is helpful to get the info before tearing apart the project. You sound like one of those guys that are afraid to ask a question because it might make you "look bad." Forums like these save the users thousands of dollars of being jerked around at dealers/mechanics. I bet Audi would tell me that I need a new throttle body....

jzkbbi

That is exactly what mine would do. If it is cold outside, it would sometimes cool down enough to happen by lunch time. If it is really really cold like winter, it would not do it at all, then when spring came would do it all over again.

aduggs

You will need to reset the throttle body though VAG-COM (see my previous post for link) to get the fluctuations to stop completely.

My engineering opinion:
On cold days, the air is more dense and therefore the air has more oxygen molecules per volume. This limits the choking affect a dirty throttle body will have.

silverd2

True, part insult in an amusing manner...therefore the smiley face. ..and part advice for someone who obviously needed it, because of the following:

I ask a lot of questions in a more organized way, that does not agonize and waste the time of others...an engineer should know this method: It's called Google and Forum search. THEN and only then, and without the fear of "looking bad", do I ask particulars to my situation that were not addressed in info I found.
Furthermore if you used this search function before addressing me, you'd have found that in a short time, I've answered countless intelligent queries and donated my own time and resources to posting detailed pictorial tutorials, just to help DIY'ers (you showed NO sign of this "title) and/or those wanting to save time and money wasted at dealers.

NO, I do NOT address questions like "where is the front of my car?", "where is the dipstick?" or "where is the throttle body?", with a serious or helpful answer.
These forums (or maybe just myself in particular) tend to deal with more advanced questions, rather than those that could be answered by an elementary school student who can spell G-o-o-g-l-e.

Engineer!!??? ....Amtrak, I must assume. Go-Stop-Open Doors.

An answer to what type engineer NOT required OR desired...by me.