When I take the car out of gear and coast to a stop, it will stay reved at around 1200rpm to 1400rpm. When I stop it will go down to 900. It seems the faster I coast the higher the "ideling" rpm is. Why is this?

Thanks
Zack S.

 

where is the car supposed to idle? my a4 idles at 500 after warm

and while coasting it'll be at around 1200 if under 55mph

 

Did you clean your TB lately? I've found that after I clean the TB my rpms will hang. Dab a little oil on the butterfly rod where it enters the TB housing and you should be fine.

 

ohh and another thing when i hit the brakes why does it drop about 200 rpms? this is of course in an a4

 

Ill try the oil on the tb, but I havn't cleaned it. It has something to do with the speed I'm at. It will never drop below 1000 if Im moving, only when I come to a complete stop.
When you coast in an A4 you dont really cost though, do you? Not like when you push in a cluch in a manual.

 

no but im just asking why it drops rpms when i tap the brakes

 

Its been asked countless times. It is absolutely normal. The engine stays at a higher RPM in order to provide vacuum for the brakes and such.

As far as you go (thread hijacker ) Your RPMs in an auto should not be dropping that low when you tap the brakes. It is normal for it to drop a bit, but no LT1 successfully idles at 200 rpm You more than likely need to clean/adjust/replace your IAC (Idle Air Control) valve or may have a vacuum leak at or near the Master Cylinder.

 

I
I know that in my 2002 S-10 the same thing happens, puting the trans in nutral while coasting dose not alow the engine to return to idle. I have not tryed this but push in the clutch, I beleve the engine RPM will than return to idle speed. if not it actualy the PCM controling the idle, keeping the engine speed higher because it can see the vehicle is moving still....

 

pushing in the clutch does nothing. I coast to a stop every time with the clutch in.

 

nono it doesnt idle at 200 rpms

but say im going 80 mph down a hill or something... its at about 2500 rpms... if i take my foot off the gas and put it on the brakes, i'll be going 80 mph and be at about 2300 rpms

 

It's normal for the idle to be higher while coasting, however if you begin to notice that it is even higher than usual, this points to a vacuum leak. I had the same thing happen in my car a couple of years ago where I saw the rpms hanging about 200rpm higher than usual while coasting in traffic, plus my engine would also bog on a full throttle launch from a dead stop. Turned out there was a hole in one of the rubber connectors coming out of the PCV area. It feels like it's beginning to do it again now though.

 

now that I reread what you wrote, I realize what you meant, sorry But, yea the same still stands for what Patman and I wrote.

O, also, the reason that the rpm's drop is simply because the braking system makes quite a draw on the entire vehicle. From electical to vacuum assistance.