Hello,

I have an interesting problem on my hands with an s4 na that is idling around 2,700 rpm even after it warms up (20minute run time).

I was wondering if anyone had a similar problem?

I have tried adjusting the idle, on the TB, as well as changing the timing.
I have also tried starting in gear as mentioned in the faq.
My rear wheels are off the ground so i tried using the breaks to slow down the engine but it refused to drop below 2,000rpm.

I tried cleaning out the TB and all intake components, verified that thrutle cable is not stock. I even tried using a turbo cpu.

I can't seem to find the source of the problem.

Does anyone have any ideas?


the car is a 1986 na that i bought before winter and in the process of restoring.


Thanks in advance.

 

i have the same problem with my 90 gxl, wont idle below ~1500, new tb, new tps, i havent changed the timing cause if on the throttle at all it runs smooth.

 

This sounds like the Accelerated Warmup System (AWS). It is supposed to keep the idle up to 2500-3000 rpm for the first 17 secs after a start in cold temps. It sounds like the AWS solenoid is stuck open, i.e. the idle bypass does not close as it is supposed to do after 17 secs.

Also check that the fast idle cam is completely off the roller at temperature, but that should only account for about a 1500 rpm idle.

As I recall, the treatment of the AWS system and its troubleshooting is much more detailed in the 89-91 manual than it is in the 86-88. See the links in the FAQ section for the manuals; look at the chapter on emissions systems.

 

The AWS solenoid valve is on the left rear of the upper intake manifold. You can check really easily to see if it is causing your problem: with the car at temp, pinch off the hose coming into the valve with a pair of needle nose pliers. If the idle drops to normal, the valve was open when it should not have been. If the idle still stays high, something else is going on.

 

Thanks for the advice.

You where almost right, however the solenoid valve is not stuck open, it's just not there . When i was putting everything together i noticed a difference in that area between my 1990 and the 86 but thought it was just a difference in models and didn't pay much attention to it.

Going to check tomorrow if i can find it in all the extra parts that came with the car.

Thanks