High Idle S4 help!
 

Just put in a new throttle body (idle air screw on the last one was f***), and the idle is still to high. If you put it in to 5th as you are coming to a stop, and drop it to a 1k or under it will stay there right around 1k, but I don't want to do that every stop haha... other then the air adjuster screw on the top of the TB what more can I do?

At what level is this high idle? Is it 1200 rpm, 3000rpm, 8,000,000 rpm??? Are you willing to share this kernel of information or is it a super secret?

Oh ha ha


Sorry about that lol it sits around 2000rpm most of the time, but it sometimes sits around 1500.

The Fast Idle mechanism on the rear of the throttle body is probably at play. It's supposed to drop the idle speed from around 1500 to 750 rpm or so. The piston of the Thermowax should extend downward to press against an upside down screw as the engine warms up. Again, this is located at the back of the throttle body. While idling for a while, press downwards on the upside down screw linkage and the idle should drop. If this is the problem then you can tighten the screw or place a large vacuum cap on top of the screw so it presses against the Thermowax piston.

Or you could have a vacuum leak. I had one from the 5th and 6th port actuators....

I have a similar problem. However, mine still sits at about 2100rpm after the cold start warmup.

Then check the Thermowax and the timing (CAS).

I messed with the fast idle mechanism, and now it sits at 1200rpm to 1400rpm. If I pull back on the throttle (pull the pedal towards the driver) it will drop down to 800rpm-700rpm. Did I over do the fast idle mechanism, and now the throttle is getting stuck?

Also oil pressure is not building right... none at idle, and it takes till 3000 rpm to build any and hold it.

Have you checked the throttle cable?

i give up on this whole idle shit hah

i have my tps set correctly, and it'll still sit at 1300 at random times ahaha :(!!

Adjusted the throttle cable, and now it idles perfect.

Oil pressure is still not right. Its hard to build over 30lbs when cursing 2500 rpm @50mph (its right at 30lbs an under), and at idle is to the point of almost not registering at all. Anything over 3000rpm it builds its normal 40-50lbs.

I have idle set at 1000rpm, so there should be pressure...

Your Oil Pressure Sender likely needs replacing.

But it was working fine, and everything before I messed with the TB... Idk I'll toss a new part at it.

Is an S5 pressure sender the same as an S4?

Then recheck/clean the connection to the sending unit. S4 and S5 versions are the same.

Yeah it would appear to have been a bad sender.
Thanks for the help Satch.

All is good in FC land! :beer:

Now its time to prepare to do oil control rings, and afreshen up on the FB :scared: