mrb63083

iTrader: (4)

I have a peculiar idle issue. The motor runs absolutely great, but I've noticed that the idle will typically sit at/or around 1100 RPM. Once I'm stopped (at a light or something), I can tap the gas and rev the motor to around 2,000 RPM, and it will drop down to about 750 (normal idle). Additionally, with the A/C on, it will idle correctly. However, with the A/C off, the same issue in the aforementioned occur.

My car is relatively stock. Other than reliability additions (Pettit AST, silicone vac lines, ss oil metering lines, ect), the only modifications to the car are; street port, downpipe, high flow cat, rb dual tip catback, bonez street-comp clutch, and racing beat street light flywheel.

My initial ideas/thoughts were that this was caused from some minor thing, such as a vac leak (I have full emissions), or something like the thermo wax valve, etc.

Any ideas?

mrb63083

iTrader: (4)

bump

arghx

iTrader: (3)

It could be the dashpot sticking.

But you should also check/adjust the idle according to the factory procedure:

--jumper "TEN" and "GND" in the diagnostic box

wstrohm

Is there a little slack in the throttle cable when at idle? Does it always return to the idle position every time someone lets off the accelerator while you hold the fast idle control down and away from its stop? Could it be a little sticky?

mrb63083

iTrader: (4)

I'll check on the TB cable. As far as I know, there isn't, or shouldn't, be any slack, but that's a good place to start. Yes, each time I tap the gas to 2k, the idle drops where it should. And again, I can turn on the AC compressor and the idle will drop to proper specs.

Gringo Grande

iTrader: (97)

First question: Do you have a PFC + Commander?

I only ask as through personal experience IMHO there is a wealth of information about bringing your idle under control with one (Mainly because it is so easy to check TPS voltages with the Commander + the FC settings, etc).

mrb63083

iTrader: (4)

No, sir. The car has the factory computer.

wstrohm

I set mine for just a slight amount of slack at warm idle. If it's tight at idle, you might have problems caused by expansion/contraction of the cable over temperature. But it sounds more like a sticky cable than a tight one.

Gringo Grande

iTrader: (97)

FWIW with your mods I would strongly consider a PFC+Commander. While they sell for $750-$900 on the forums I've personally picked up (and seen) other sales of them for under $600 for the two together.

After learning more than I ever wanted to about idle issues the last few weeks...

1) Search all threads using the keywords idle issues.
2) Key on threads by arghx
3) There are several potential culprits that will effect your idle:
- Vac leak
- Fast idle Cam
- Air Adjustment Screw
- Dashpot
- Throttle Adjust Screw
- Secondary Throttle Adjust Screw
- TPS
- Throttle Cable

Good luck!