SilS4

My car has about 52000 miles on it now. Something I recently started to notice was after not driving my car for about 6 hours (eg - when I get up in the morning to go to work) the car will idle at 1500 RPMS for about a minute or two. Then, it will seem to slowly drop to about 750 which is where my car has always seemed to idle before now.

Also, when I drive the car between where it normally idles (750 RPM) and the mysterious idle speed (1500 RPM) the car seems to have very little boost if any.

Anyone had this problem before?

My dealer is fairly unhelpful when I bring my car in anymore, so I would like to give them a little direction to try and find out why this idle RPM is so high. Any pointers/suggestions would be helpfull.

Thanks..

mpwolf

warm the catalysts quickly. It should have done this from the start.

SilS4

My car, until recently, ALWAYS idled at about 750 RPMS. I have talked to the service people at my dealership about the problem and they said they couldn't find anything except for a MAF was a little out of spec. So, they replaced that but I still have the problem..

mpwolf

So, even when cold, your car always idled at 750 from the start?

SilS4

At about 46000 miles it started idling at 1500 RPMS when started cold. Before that, it always idled at about 750 when started cold.

mpwolf

leak, that can lead to a handful of problems.

George @ BostonAudi

Not great for the engine, but significantly reduces emissions.

1500rpm is a tad high, most S4's I've seen do more like 1200rpm, but I wouldn't be freaking out if I saw that on my car.

DocSlow (Mini Pig)

I idle aroun 1,000 and go down to about 800 rpm. It is normal to go down as the car warms up, but I don't know about starting at 1500!?

CatOne

When the car is cold, it will idle higher. That's to get it warmed up and not have it die when it's a bit tougher to turn over.

How old are you? Must be less than 22 ;-)

Plus... no boost at < 1500 RPM is totally normal... you need air getting to those turbos to spool them up, and at 800 RPM you don't have it. NEVER floor it at 800 RPM FYI... it's hard on parts.

S4mig@PEB tuning

I had a problem with idling at 1100 rpm when cold, and I was getting EPC light quite often which always put me limp mode. Vagging it came back with "Throttle actuation potentiometer range/performance" If you dont have any EPC's yet, I'm willing to bet you'll start getting them soon as it took about 2 weeks for them to pop up in my car after i first noticed the high idle.
I took it to the dealer and they ended up replacing the potentiometer if im not mistaken. Quick fix for them but my service manager told me they still billed AoA for $1200 dollars of work. Now I also had my BPV's done at the same time though which shouldnt have been long, most of the time I imagine was finding the problem as they orginally wanted to replace my entire throttle body. Hope this helps you out.