Hi, I recently installed the Power FC on my 93R1. Planning to get it tuned by Steve Kan but we're trying to work out a date and place atm.

My problem is this: When I first turn the car on, it idles steady but high, at around 2.5k. Once the temp reaches roughly 83 degrees, the idle drops and surges between 800-1500rpm. It does about 5-10 surges then settles down to a normal idle @ around 800rpm. The idle will then stay steady until I hit the accelerator, then it starts surging again until it settles down.

Ive tried the idle learn thing a couple times already and it seems like its gonna be okay, but then it just does the same thing all over. Please help me out. Thanks.

 

This is the most often asked question by newbs and a good search would have found many answers.

Find the Air Adjusting Screw under the right side of the throttle body and screw it in to reduce idle air flow. You manually have to help the PFC control idle since it is more efficient at running the engine. You might alsp need to adjust idle fuel some. This is part of tuning the PFC.

If you have not already done so: download the manuals from one of the sites listed in the 3rd gen forum stickys. The study all about the FD engine control systems.

 

Okay, I guess i should have mentioned I have already searched. I've tried adjusting the idle screw to no avail. How do I adjust the idle fuel though?

 

Then maybe :
(0) the throttle cable is too tight preventing full closure of the throttle body.
(1) someone over opened the Throttle Adjusting Screw (TAS).
(2) the TPS voltages are way off, read about the ETC-Sensor Commander screen.
(3) you have an air leak due to a loose or broken hose.
(4) maybe the ISC solenoid is dirty or has crap in the valve. Remove and clean.
Have you checked all of these?

The PFC manual shows how to adjust the fuel cells in the Fuel Correction Map.
But you SHOULD play with the temp fuel changes as mentioned on page 30 to safely learn.

 

Okay cool, thank you for the detailed info. I'll check out those things when I have time this weekend.

 

PFC Idle control sucks. Work on it forever, if it doesn't get better just unplug the ISC and setup the idle manually, there are instructions in the archives.

 

It can be a tuning issue if mechanical stuff all look ok. don't worry... i had really similar problem and Steve fixed it w/ the tune. now my car drives and idles perfect.

especially if it idle surges when you're under load or have a/c on, or even when just cooling fan turns on... and it bounces for a while until settled...

make sure you mention it during the tune, and also if you have any other idle or driveability issues.. like if your idle takes a dip when you come to a stop from in gear to neutral, weird turbo switchover, ..etc..