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Thread: Newbie question regarding Red/Blue PCMs

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  1. #16
    Fuel Injected!
    Join Date
    Jan 2013

    Finally got around to pulling valve covers and getting cylinder head casting number...10235772. From my online research and reading, these were the "best" 96+ heads to use when rebuilding a Chevy 4.3L V6. As for doing any port-matching of the intake-to-head mating surfaces, I have to admit that I didn't do anything in those areas since I had no previous experience doing that so just ignored it. Were you successful in confirming the potential effects of different heights having an impact? Because this was not a serious performance build, I wasn't concerned with it when I put the motor together.

    I found my vacuum gauge and will begin a serious and methodical search for any leaks in the top half of the motor.


    UPDATE: I hooked up my vac gauge to the EGR vacuum port at the base of the TBI. After several cycles of start, run, rough idle while struggling to keep running, then dying, restart again, struggle, and die once more, the motor finally settled down to running longer than 30 seconds to a minute. With the vac gauge installed, the readings started at 20 lbs, the bounced between 16.5 - 18 lbs. After several restarts, the engine would idle until I turned off the key. What appears to have been a marking point was when the engine temperature reached around 200 deg F which resulted in the radiator fan kicking on. Don't know if the temp is is of any significance but I thought I'd mention it. After letting the engine cool, attempted another restart and it started up and ran fine. After these multiple restart, I am now beginning to under if the ECM "learned" something and is now using those settings to control the motor.

    As part of arriving at this somewhat acceptable condition, I did a few other checks:
    (1) sprayed starter fluid along the mating surfaces between intake and heads - NO CHANGE
    (2) sprayed fluid onto the base of the TBI as well at mating areas for sensors--TPS, IAC, and MAP - NO CHANGE engine started, idled, then died.
    (3) disconnected ESC - NO CHANGE engine started, idled, then died.
    (4) disconnected TPS - NO CHANGE engine started, idled, then died.

    I will return tomorrow attempt to start the engine and continue to monitor performance.
    Last edited by 57 Handyman; 08-20-2017 at 07:02 PM. Reason: added information

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