fc3s7

First thing I would check is the injector wiring - ECU's fire the injector by pulsing to ground, and it sounds like youv'e got a short to ground for that injector. If that's the case, the #5 injector would be FULL OPEN all the time - definitely running the car rich .

Modern ECU's are typically REALLY hardy - I would moreso suspect the wiring or the injector.

Dale

Supra4100

I wondered about the whole short in the wiring bit. But after careful inspection of the bit I could trace down. I have a hard time believing the insulation of the wire would just deteriorate away. Following that specific wire It has been untouched. I also checked the pulses with a noid light. It blinks rapidly, but tends to have short wide open bursts of light. where the other 5 injector leads blink rapidly as they were supposed to. One last thing I wondered if it were a leaking injector, so i swapped with number 1 and it works fine for that cylinder.

sc3boost

hey i know this is an old thread but did you geys ever figure out what the problem was, i have the exact same problem. 92 sc300 5spd, and for the love of god i cannot figure it out. for this reason i'm always in a bad mood, so before i start a new thread i just wanted to know if you guys figured this one out

Nateboii24

It is the ECU. No body updated it but there are lots of threads on this subject

Supra4100