Ok guys and gals here is the problem I'm having with my 1992 JDM FD3S, as soon as I start the car the engine will immediately rev up to about 3500-4000 RPM and stay there. I can still use the throttle and it will rev higher than that but it won't come down from there.

Some background on the car: I recently bought it from a salvage auction with some minor front end damage (broken bumper and FMIC). I found that the ECU was missing and that there was some damage by the ECU connectors (brittle wires had broken). I got a 2nd hand ECU (USDM, could that be the problem?) and repaired the damaged wires and the car started and idled however just a bit rough, which I chalked up to the lack of FMIC piping at the time.

Once I finished installing the piping it started and idled (though still rough/rich) I revved it a few times and it seemed normal then suddenly the problem began. It revved up to 3.5-4K RPM and stayed there and I haven't been able to get it to idle since then.

The car has a new set of plugs and wires (I've double checked that they are installed correctly) and I've checked the wiring to the TPS and it seems fine and the throttle cable itself seems fine as well.

Any ideas on what could be causing this problem?

Thanks in advance.

 

There are few different things between JDM and LHD Fd3s, ecu wiring.

 

sounds like the accelerated warm up system is stuck open

 

Disconnect the throttle cable for the front of the throttle body and see what happens.

If that doesn't resolve it remove the intake elbow and ensure the throttle plates are closing.

If you haven't removed the manifold then it is just an issue with the throttle not closing. If you have removed the manifold or items from the manifold it could be a huge vacuum leak. Should be very easy to diagnose. I'm betting its the throttle plates.

 

I recently had a similar problem after the car had sat for a few weeks. The secondary throttles were jammed, and after revving, they wouldn't close. So my idle just went higher and higher. Easy to check, just try to twist them in the engine bay and see if they retract by themselves.

 

Thanks for the responses guys, not sure what it was exactly but I cleaned and inspected my throttle body and at the same time disabled the AWS and the problem is solved.

 

Sorry to hi jack your thread but i just have what i hope is a quick question. Iv notice that after driving my car for like 15 min, then say go fill up with gas and restart the car, the idle jumps up to 3k rpm. After like 30 sec it goes back down to normal idle speed. Any ideas? Also at one time it was jumping from 1k-3k for like 20-30 sec.

Iv only owned the car since feb and this was my first weekend taking it out of the garage.

Mod list- apexi pfc and full turbo back exhaust.

 

Its normal for it to do that. Its the warm up system.

 

I thought the pfc gets rid of the warm up system.

 

any more ideas on this? things to check?

 

the PFC only gets rid of the AWS if you tell it to.....otherwise the system will operate normally by default if everything is still connected.

 

Oh. I don't know how to check if it is turned off or not. On a normal cold start first thing in the morning my idle sits at around 2k rpm.

The problem I am experiencing only happens when I shut the car off and turn it back on within 10 min.