bad ECM ?

Discussion in 'General Chevy & GM Tech Questions' started by RATRODKING, Oct 10, 2012.


    RATRODKING Rockstar 100 Posts

    i have a 1990 k-1500 4x4 with 5.7 and automatic. has 154k miles. i have had it for 4 years now. and has been running great. recent distributor and complete tune up, including ignition module, that came with the distributor, coil, wires, rotor, cap and spark plugs.
    from the first day i bought the truck, after about 2 miles on speeds over 50mph, i would get a check engine code flash. i checked the code, and it was a 32, EGR valve... never replaced it because it ran fine.
    about two weeks ago i started noticing a slight pinging when it shifts into overdrive and i give it some throttle. very slight ping.
    this past weekend i did the spark plugs and wires, and for some strange reason it has now been idling funny when in park. it surges slightly, i would say 300-500 rpm. never stalls though. runs good other than that, but still get the slight ping. i always use regular gasoline.
    now i am also getting a 4-2 code, which is an ignition control circuit. the book says to check the connection on the distributor ignition control module, or possibly replace the ECM.
    since i am still getting the 3-2 EGR code, tomorrow i am replacing the EGR valve, the EGR vacuum solenoid, and the knock sensor. \

    a friend said also it might be the idle air control valve ? .... i guess i might thry that before trying a new ECM.....

    looking in the book it seems to be fairly easy to replace the ECM, under the passengers side dash ?

    just curious is someone might point me in the right direction...... i hate throwing parts at a problem without knowing for sure, but at least it will all be new.... a few hundred dollars in new parts is netter than a new truck payment, i say..... if it fixes the problem.

    just curious if anyone has had the same symptoms i am having, the surging idle, and what you did to fix it ?

    thanks guys...

    RATRODKING Rockstar 100 Posts

    just remembered i have a new ignition module... so i will replace that also tomorrow, along with the EGR valve and solenoid and knock sensor...
    thanks guys
    hope i dont need an ECM

    RATRODKING Rockstar 100 Posts

    ok guys, today after work i installed a new ignition module, EGR valve, EGR vacuum solenoid and knock sensor.
    although i have only tested it in the neighborhood, i think i have fixed it. it now idles very smooth with no surges. tomorrow when i get on the highway to work i will be able to tell if the check engine light comes on again, and will see how it idles after its fully warmed up....
    update tomorrow...

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