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Thread: anybody know where the cylinder 1 ignition signal wire is on 3800?

  1. #1
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    anybody know where the cylinder 1 ignition signal wire is on 3800?

    I bought a knock monitoring device I want to hook up for knock per cylinder and I need to hook into the signal wire for cylinder 1. I know it's in the group of wires that plug into the ICM under the coils but IDK which one it is. Anybody point me in the right direction?
    2018 Camaro SS, Maggie 2650, 103 TB, Big Gulp, E85

  2. #2
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    I must say that's one thing I never looked into with my GTP. If no one here can help you, see if you can get ahold of Paul from PRJ Performance. I know he is kind of out of the business end these days but he may know which wire you're looking for off the top of his head.

    Good luck.

  3. #3
    Advanced Tuner Dr. Nopps's Avatar
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    Don't forget your vehicle should also support a PID for individual cylinder missfire count/history. If you are diagnosing I hope this is at least of some assistance.

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    thanks guys. I'm just trying to get my knock monitor setup for 3800's. People tend to forget some knock sensors get false knock and others are just too loud to audibly hear knock. Not fun trying to tune 1000+hp engines with questionable knock sensors. Haven't blown one up yet and I plan on keeping it that way.
    2018 Camaro SS, Maggie 2650, 103 TB, Big Gulp, E85

  5. #5
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    hmmm, found this link. I wonder how I can tap into this to find out when cylinder 1 is firing.

    http://easyautodiagnostics.com/gm/3....-sensor-test-1
    2018 Camaro SS, Maggie 2650, 103 TB, Big Gulp, E85

  6. #6
    Advanced Tuner Dr. Nopps's Avatar
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    If in the northern hemisphere you're supposed to hold onto the spark boot with your left hand, southern hemisphere - use your right hand - just kidding. All your listed vehicles come with a factory tachometer so I will assume this isn't just for external RPM reference, and actually has to be cylinder 1. Try the input side of the coil pack for cylinder 1. If it's simply just RPM that's needed for calculation with a non tach equipped vehicle you can tap into the crank sensor signal wire going to the PCM.
    Last edited by Dr. Nopps; 10-10-2015 at 08:26 PM.

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    I can tap into tach for rpm or I can tap into the cylinder 1 signal wire. With the cyl 1 signal I get knock per cylinder, with tach or injector I only get rpm. I would like knock per cylinder. I'm just not sure how I would tap into input of the coil. Pretty sure they are flat against the icm on the 3800's.

    Btw this is a plex knock monitor I'm talking about.

    http://www.plex-tuning.com/supportdo...nual_V2.0.html

    Under step by step installation step 3 it goes over the possible methods. On an LS it's easy you just tap the signal wire going to the coil. On the 3800 it seems its not that easy

  8. #8
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    This is the schematic for your ICM there is no cylinder 1 signal its calculated within the ICM based off of the crank and cam signals. Maybe you could find a way to tap off of the teminal for cylinder one under the 1/4 coil pack.
    Attached Images Attached Images

  9. #9
    Just thinking out loud here. Could the #1 inj control ckt be used to synch #1 cylinder?

  10. #10
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    Injection and spark do not happen at the same time. I'm pretty sure for what he is trying to do he needs cylinder one spark signal. I think slipping some sort of terminal over the cylinder one connection under the coil pack is probably the only way to monitor the actual cylinder one spark event other than on the plug/plug wire itself.

  11. #11
    The problem he will run into is that this is a waste spark system so the #1 & #4 cylinder coil will spark with the same ICM input.
    I don't know of a way to separate out just #1
    -Greg
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