...the RPM to drop on the auto trannies when you shift from Park to Drive? Is it the IAC or some other sensor? Just checking, as m,y car will idle at 1100 rpm in Park but when I shift to Drive or Reverse, the rpm's drop to about 300 and bounce around for a coupke od seconds and then setlle in at about 900rpm. I don't want to through money at a new IAC if it is not the cause. It also has a somewhat erratic idle, but only around 50-100 rpm when settled in. Any idea? Thanks,

Kyle

 

ttt

 

I knew you were on here Ford. I guess by your repsonse you don't know the answer, eh? Thanks,

Kyle

 

I'm stumped at the simple fact that you can get your car to idle at 50-100rpm.

 

I meant to say 50-100 rpm variation from normal, which is about 900 rpm. So, it would drop as low as 800 and go up as high as 1000. Sorry for the confusion,

Kyle

 

O I get it.....

 

So you have an auto and your idle in park is 1100? I think it should be more like 950 and 750-800 in gear someone correct me if I'm mistaken. you MIGHT have an air leak somewhere or did you have your PCM flashed? With my Lunati cam and manual my idle did not change its still at 850-900rpm's. the sudden drop in rpm's can be contributed to a vacuum leak.

 

Mine idles at like 800 rpm in park and about 550 in gear. Has always made me nervous , but it sounds cool sitting at the light!

 

mine idles at 850- 900 but its an M6.

 

When I originally flashed the PCM with the new cam/heads program, it did idle at stock rpms. The reason I had the rpm's raised was due to the drop in rpm's when I shifted from park to drive. The car would almost die. I would rather have it idle at stock rpm's and fix the drop. That is why I am asking what causes the rpm to drop when shifted. Thanks,

Kyle

 

Like I said do a check around your engine bay and listen for any whistling or check your intake gaskets, TB gasket,.. If it used to idle perfect and then acted stupid, you could have had something either come loose or the heat cycle created an air leak. check your bolts and make sure every one of them is tight.

 

It ran fine before the heads/cam/TB but since it ihas done this. I guess I ran into doing too much at one time. lol What is the purpose of the IAC? This is just a stock ported throttle body but is not mine so I am assuming that the IAC is not mine as well. Thanks for the responses so far,

Kyle

 

To answer your question, the idle speeds are programmed into the PCM, as you have already noted. With the A4, there is a place to program one value for "in neutral" (650rpm stock) and another place to program a value for "in gear" (550rpm stock). It is supposed to drop 100rpm when you put it in gear, at least with stock programming.

The "IAC" is not a sensor... it is an "actuator"... its the valve that opens and closes to set idle speed.

 

After the initial drop, the idle rpm's do settle in at the programed idle. It's just the intitial drop that has me concerned. From Park idle, I shift to Drive or Reverse and the rpm's instantly drop to about 300-400 rpm. After a couple of seconds, it returns to the set idle of about 900 rpm. What causes that? Thanks,

Kyle

 

TTT