Hi all, 92 3000gt vr4.
I’m in the process of restoring this car, and getting it back to a good stock running condition. Undoing alot of the previous owners shenanigans. Car presented with a bunch of issues, chief of which was a bad idle, which i’ve gotten better but still isn’t where I’d like it to be.
Currently, on idle the car will generally sit at around 800rpm and pulse between 700-900rpm. Occasionally, the idle will fall dramatically down to nearly zero and will bounce back to 900 and do that a couple times. Nothing that i can point to that will cause it to eventually settle back down. Sometimes it doesn’t. Sometimes it’ll do this on startup, cold or hot. Sometimes after driving a while and idling at a stoplight. Seems ‘random’.
Quick list of things I’ve done around this issue:
- replaced both 02 sensors with good name brand.
-endless boost pressure testing and leaks fixed.
-replaced chinese MAF with used known good compatible Mitsubishi MAF
-Mitsubishi ISC installed
-Set TPS, BISS, idle screw/throttle plate all per manual
Good things to note:
- Car has a aftermarket Chromed ecu that I can’t talk to in depth because I don’t have the correct Tactrix.
- I do have a blackstealth reader that I can gather basic information from. Such as my fuel trims at idle generally sit between 100-110 in both banks.
- Trying to set the idle per grounding the brown plug doesn’t seem to work correctly. In the manual, if you ground that plug the idle should change. When I ground it, nothing happens.
- Driving it feels great. Sits in boost without issue.
In my head, I really want to see whats going on with that ECU. And my troubleshooting up until this point has been around everything except the actual ECU, in that its an expensive thing to address. A tactrix cable is around $500 USD if i can find one, and so would be a compatible used refurbished ECU…so i’m trying to address everything cheaper than that first. So have i exhausted all my options here? Appreciate the advice.
Mike.