Just curious as to what RPM range everyone is at when they are at idle. For some reason my car will idle at 1K for the first couple of miles (stop and go traffic) and then will later dip to about 500 RPMs and a rougher idle. Any ideas? Only mods are in the sig. Thanks.

 

Mine does the same thing. I believe that the computer does this to bring the engine up to operating temperature.

 

The car will idle high untill the engine is warmed up, then the rpms drop down. I idle around 600 when it is warmed up.

 

I believe that (other than the roughness) that is about right for and A4. My M6 idles at ~1000 until at a complete stop then drops to a smooth ~800. I believe the factory spec for idle on A4 cars is ~600 RPM and ~800 for Manuals.
Seems backward from what other cars (at least in the past) where spec'd for. It use to be that in park/nuetral recomeneded idle for a car was ~600 RPM for manuals and ~800-900 for auto's to make up for the drop in RPM when you put it in gear while stopped. Maybe the computer controls change all that common sence stuff for auto's but that don't explain why the manual's factory idle is set so high, these cars certainly don't have a problem with low end torque that you have to overcome!

 

Thanks to all for the quick replies. I'm glad to hear that it's pretty common. I guess that I had never really noticed it before. As for the rough idle, it'll idle for the most part at about 500-600 RPMS and then will drop intermitently by about 100 RPMS and then immediately go back up to normal. Doesn't seem to happen all the time though.

 

Is your AC on while its doing this?

As for stick shift cars idling at 600 RPM, I've never heard of that. My 1973 5 speed idles at 800 RPM stock, and automatics were set for 600 RPM, this helps make it easier for drivers to only give a little gas to take off instead of killing the car at lights all the time. Since the automatic is going to slip the clutch packs for you, its not a real issue for A4 cars.

The guages are not 100% accurate on the car either, so mine always appears to idle at 950/1000 RPM when its 800 in the PCM.

 

Now that I think about it, I usually do have me defrost on so that would be a yes to the AC. After all these comments, can't believe that I really didn't think about some of these. It really wasn't until after I used Sea Foam a while back on my engine and throttle body did I notice the idle at all.

 

800 in gear, 900 in neutral or park via ScanMaster.

On the tach, it looks like 1000 in gear, 1100 in neutral.

 

Kain, wouldnt you idle higher because of the cam?


Chris