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Thread: LT1 coil conversion

  1. #31
    Club Member 1BADAIR's Avatar
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    Small bore ls7 is where al the fun is
    A gun is like a parachute. If you need one, and don't have one, you'll probably never need one again.

  2. #32
    Club Member mustangmike6996's Avatar
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    A little update on my optispark issue...

    So the timeline goes something like this:

    2011- replace Opti and ICM (no spark)
    2011-2014, mostly stored, some short trips every few months
    2015- drive the car to work as a daily for the season
    2016-2021 car is mostly being stored again with occasional trips
    2022-present... No spark diag

    For the diag, I followed the troubleshooting chart in the Factory Service Manual. Initially I had diminishing spark but could run the car on starter fluid (I'm assuming because it's more combustible than fuel). Eventually the spark completely quit. I replaced the ICM and coil with OE Delphi and AC Delco parts. No spark. Started the diag process all over from step 1. It calls out the distributor. Can't find a good/cheaper replacement so I go with AIPs sensor for $65 and replaced the opti extension harness with a new aftermarket parts (goes from the intake down to the distributor). Put it all back together and no spark... At this point I start the diag process again. Instead of pulling the opti connector I was pulling the intake side of it (it's easier to access and read voltage/gnd). I keep diagnosing the car, which now needs a battery but I use my jump box to aid the weak battery. I finally get completely fed up with the car and start back at step 1. Check for power at pin C, has power, check for ground at pin D, missing. Thinking I flipped the connection in the process, I reached and gave GND on pin A. I stop and ask WTF, is that harness pinned wrong....YUP, the new harness was pinned backwards.

    So long story long, I transposed the pins and got spark. At this point the car is completely flooded (brand new plugs too). I come back today with a new battery and retest, got the car to stumble and start/stall etc. Eventually I got it fired up and cleared the overly rich condition.

    Tomorrow I'll be reinstalling the water pump and letting it start/run and heat cycle a few times.

    It's been a hell of a time with this.

  3. #33
    Club Member dave89iroc's Avatar
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    I do recall those jumpers being pinned wrong at times
    ASE Master Certified Technician

  4. #34
    Club Member mustangmike6996's Avatar
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    Quote Originally Posted by dave89iroc View Post
    I do recall those jumpers being pinned wrong at times
    I contacted the company, they confirmed that they did have a bad batch and think they have them isolated.

    I just reinstalled the water pump this weekend. The car fought me when trying to restart but eventually ran (poorly). I think I am fighting old gas and fouled plugs. I plan to swap the plugs some point this week if possible and retest.

    When I did get the car running and up to operating temp the service engine MIL tripped. I jumped the ALDA and got code 26, quad driver fault. From what I dug up really quick, this is possibly a wiring issue to the purge valve, EGR or air pump... or ECM. I need to verify all of those circuits are ok. I am wondering if the harness that was incorrectly pinned caused any ECM damage.

  5. #35
    Club Member dave89iroc's Avatar
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    Quote Originally Posted by mustangmike6996 View Post
    I contacted the company, they confirmed that they did have a bad batch and think they have them isolated.

    I just reinstalled the water pump this weekend. The car fought me when trying to restart but eventually ran (poorly). I think I am fighting old gas and fouled plugs. I plan to swap the plugs some point this week if possible and retest.

    When I did get the car running and up to operating temp the service engine MIL tripped. I jumped the ALDA and got code 26, quad driver fault. From what I dug up really quick, this is possibly a wiring issue to the purge valve, EGR or air pump... or ECM. I need to verify all of those circuits are ok. I am wondering if the harness that was incorrectly pinned caused any ECM damage.
    I hated those quad driver faults, just so unspecific , good luck, sounds like you're getting close
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  6. #36
    Club Member mustangmike6996's Avatar
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    A little update...

    I pulled the newish plugs and put in a cheap seat of copper Autolite plugs (I can clean those if the get carbines up during diag). The car would start but not run great and stall at idle.

    As for the quad driver DTC, that was my fault... I didn't have the air pump connection fully seated. Oops

    I was brainstorming with a buddy and he mentioned the cats being plugged. Well, I thought I had a weak starter +it was cranking slow and surging). I dropped the passenger side pipe at the manifold and the car cranked faster/better then fired up quicker. I did the same to the driver side, dropped the cat and the car cranked good then fired up but it needed throttle to run. I could get it to run great at 1200-1500 RPM but it still doesn't want to idle. I think it's got an air/fuel issue. At 1200 RPM I was at 17 in/hg vac with slight fluctuations when it would stumble a bit.

    So... Now I need to pull the cats the rest of the way out and make a legit catless test pipe (I'm not paying $900 in cats until I get this drivability issue sorted out). Unfortunately it seems like I'm going to have to drop the whole exhaust to pull the cats. Then punch the media out, reinstall and retest. I'll probably have to get new upstream O2s (I'm betting they are fouled to hell now)

    Once that's all reinstalled I can focus on the poor idle quality. Then hopefully get the car reassembled and running this summer.

    I would also like to mention that whoever worked on the C4 engineering packaging team can go kick rocks. On top of the usual 80s-90s GM usually mixed metric and SAE bolts, some fasteners are puzzling for placement. I am lucky enough to have a good set of professional tools and I'm working on a car that's not seen snow/salt. I can't imagine doing this job on a usual 30 year old MI car.

  7. #37
    Forum Member ultradriver10000's Avatar
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    Cut the cats out and weld in straight pipe. The cats are worth decent money, maybe 80-100 each.

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