Weird Idle Hunt
 

Guys - I need your help !

I have searched and I am a bit confused with what I have seen

Problem:

Idle is fine when warms up and for some time afterwards

Then, often in start/stop trafic or when I go hard on the gas and then stop, idle hunts between 500 -1,000 rpm (2-3 times usually) and then settles perfectly - This will happen again and again and then when temps drop will come on and off

I have a Power FC for 3 years but only now has tis problem started

I have checked for vacuum leaks, none

Any ideas ?

Many thanks

Riccardo

Adjuted TPS voltage from Power FC
A bit better, but again no luck

I had some electrical issues(actually still do) that caused my idle to hunt quite a bit at one point in time.

Check your throttle body settings. Especially the air adjustment screw under the throttle body.

Might also want to inspect your grounds just in case.

Thank you guys!
I have adjusted throttle body setting incl. air adjustment screw
I have a superb ground kit so I think I have this squared
Electrical issues however is an interesting one...

how long has it been happening? Have to changed any parts lately?

Weather has become quite hot suddenly - does its since 3 weeks ago
Added traction control & wisesport kit but is I think is irrelevant (I have in any case tried with no traction - off position, still problem)

nevermind, i take it u got it fixed??

No not yet unfortuneteley
Next try over the weekend - no time over the week due to work
However I am tryuing to collect all solutions

I am still looking for the problem, apparently this happens when under heavy electrical load, and in particular when the fans turn on
Any ideas ?

i have this same exact issue on mine as well. didn't happen until after I the the PFC tuned. I'm sure it wasn't the tune, but maybe during the tune the TPS might've went wrong?? is that possible??

i never drive my car as hard as it was for the couple of hours during the tuning session. so i've been searing for a solution to this problem. I haven't gotten around to check the TPS, but that's the first place i'm planning to look.

This is very interesting
Please keep me posted
I will do so too

Link (& Riccardo) -

I've seen that happen before on 3 different cars including mine. Usually after a tune or climate change. Its usually b/c the base mechanical throttle body settings are not properly adjusted - in other words too much air is coming through the throttle plates for the amount of fuel being delivered.

On my car for example, when I started going through the throttle body settings using Chuck's tuning notes I found that the Air Adjustment Screw under the throttle body was out 11 1/2 turns. Normally it should only be out 2-3 turns. When I went through all my throttle body mechanical settings, it actually wound up readjusting the TPS narrow value by .1 (or was it .01). Going through all of those throttle body settings fixed my issue. Adjusting TPS or one of the idle settings individually is usually not enough to fix an issue of this nature. You got to go through the whole thing.

If you have a PFC, Chuck's tuning notes are an excellent investment not just for tuning but also for fixing stupid things like this. I think they were about $40-60 and it was the best money I've ever spent on my FD.

Riccardo might also consider removing and cleaning the Idle Speed Control with some carb cleaner as that can sometimes get clogged with gunk. Dale Clark had a write up on that iirc.

Good luck.

It will probably fix itself after 750-1000 miles.

Idle tuning
 

Dale Clark's notes are also useful:
http://www.clubrx.org/media/pfc/PowerFC_FAQ.pdf

I had the exact same problem on my FD, I ended up replacing the dash pot, it was dead, adjusting the AAS per Dale’s notes (really touchy, it needed to be closed to about 1 turn), and I also needed to make the F/C and Idle setting pairs near the same on the DL settings page 1.

With some trial and error I got it to work well, every situation will be different.