scrotenz

Hi All,

I have been chasing a variety of issues all noticed while chasing an high idle issue since purchase 2 years ago. Its a 92 4x4 sapphire cosworth stage 1 MSD chip (can list more specs if relevant).

So history so it hopefully makes sense. Idles always since ive owned it at 1000rpm cold and 1500 hot 17psi boost. Has misfires, terrible cold start, poor fuel economy, puffs of black out exhaust and big backfires and car runs even more poorly until i turn off and on again if it doesnt die on its own. Changed CTS, Cleaned ISCV checked idle screw(wound right in!), changed distributor and rotator arm and plugs. Still no change except a little less misfires so i thought. Changed all intake gaskets and intake as i found a crack. Still no change to high idle. checked for vacuum leaks spraying brake cleaner around.

Breakthrough came when testing sensors at the ecu to find the phase sensor and knock sensors where plug around the wrong way by the distributor. Eg tested continuity for phase sensor on pins 23 and 5 but nothing but found on pins 22 and 6. So i switch the plugs from phase and knock and presto they tested correct eg phase on 23 and 5 and knock on 22 and 6. During this all other sensors reported within tolerance and varied as expected as temps raised(Air and coolant temp).

Im assuming here based on the phase and knock sensor that it was in limp mode etc and retarding timing lowering rev limit erratically etc.

Im assuming here based on the phase and knock sensor that it was in limp mode etc and retarding timing over fueling and lowering rev limit erratically etc causing the misfires and poor performance.

So after i found the sensors plugged incorrectly and changed them the idle was still at 1500 and now the Amal valve was clicking as soon as i pressed the accelerator and boost at was now at 9psi. I read somewhere that this can be caused by TPS set incorrectly so after testing i found idle at 0.04 and smooth up to 4.71v at open throttle. Ive set this now to 0.25v at idle while cars at operating temp with ISCV disconnected no fans on or load. Idle set to 900-950ish Rpm. Plugged in ISCV idle raised and settled back to 900rpm so Yay sorted. car at cold now idles about 1200 and settles back to 900 when warm. to confirm all good i disconnect the ISCV while clod and idle drops and while warm doesnt cahnge. BUT now the Amal valve does not click at all and boost at 9psi still.

Im expecting 17psi(stage) so ive tested the amal valve. 12v as expected while car running. continuity in earth wire to ecu on pin 16. but its clicking when disconnected. Ran 12v straight to amal and earthed to body of car and it clicks when connected so its working. What i am taking is that since ive adjusted the TPS then the ecu is not sending earth to the Amal valve. Directly earthing the valve and using the 12v of the ECU pin 20(also Fuel pump) and it clicks as expected.

Im assuming that since ive adjusted the TPS that this is causing the amal valve issue. I have read various recommendations to set the TPS to 0.25 or 0.35 or even in a diagnostic document to set it to 0.6v? What is correct? Is 0.25v at idle affecting the amal valve to not be earthed by ECU?

What else do i need to check or is it as simple as the TPS needs to be changed?

Please note that the cam belt has been changed while the sensors were switched so assume set while in limp mode? So this may be a factor? I do not know what the CO% is set to or fuel pressure. Since it has an MSD chip with a serial number i have emailed MSD for advise on these and hoping they can assist.

Any help or guidance or even clarification on my waffle?

Thanks