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Thread: LT1 trouble shooting help

  1. #21
    ICM issues are what led to us doing the LS1 swap. I never figured out why but the car was eating them every two sessions. The ACDelco ones would last longer. They all exhibit the same symptoms though, I would loose ignition for a few seconds once, then about 10-30 minutes of track time later it would go out completely. It was a contributing factor to the grass fire at TWS (along with leaking oil and my stupidity of putting in the grass). The last time it happened the car back fired horribly, ringing ears and all. Did it again when I tried to fire it at the shop.

    I wanted to try this kit, but adjustable timing is against the rules.
    https://www.jegs.com/i/MSD-Ignition/121/83811K/10002/-1

    I just now found the piece parts I *think* you need to eliminate the ICM by itself. Not sure on the rules status of it but in the spirit of the CMC rules I'm going with illegal. If I had found them earlier maybe I would have tried them out.

    Pig-tail
    https://www.jegs.com/i/MSD-Ignition/121/8876/10002/-1

    Digital ignition
    https://www.jegs.com/i/MSD-Ignition/121/6425/10002/-1

    - Josh
    CMC #50

  2. #22
    Senior Member Carroll Shelby marshall_mosty's Avatar
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    Quote Originally Posted by Trublu View Post
    Check the float bowl levels
    Isn't that something that's only legal to do in Colorado at the moment??
    Marshall Mosty
    AI/SI Texas Regional Director
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  3. #23
    Senior Member Carroll Shelby
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    Quote Originally Posted by Sook View Post
    ICM issues are what led to us doing the LS1 swap. I never figured out why but the car was eating them every two sessions. The ACDelco ones would last longer. They all exhibit the same symptoms though, I would loose ignition for a few seconds once, then about 10-30 minutes of track time later it would go out completely. It was a contributing factor to the grass fire at TWS (along with leaking oil and my stupidity of putting in the grass). The last time it happened the car back fired horribly, ringing ears and all. Did it again when I tried to fire it at the shop.

    I wanted to try this kit, but adjustable timing is against the rules.
    https://www.jegs.com/i/MSD-Ignition/121/83811K/10002/-1

    I just now found the piece parts I *think* you need to eliminate the ICM by itself. Not sure on the rules status of it but in the spirit of the CMC rules I'm going with illegal. If I had found them earlier maybe I would have tried them out.

    Pig-tail
    https://www.jegs.com/i/MSD-Ignition/121/8876/10002/-1

    Digital ignition
    https://www.jegs.com/i/MSD-Ignition/121/6425/10002/-1

    - Josh
    I wonder if this and and good clean Opti is all that's needed to make an lt1 run right?

    ICMs gave me some trouble too early on.

  4. #24
    Senior Member Carroll Shelby Supercharged111's Avatar
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    Quote Originally Posted by marshall_mosty View Post
    Isn't that something that's only legal to do in Colorado at the moment??
    Looks like your options are expanding.
    Attached Images Attached Images
    RM CMC Director

  5. #25
    So i was finally able to get the computer to read the PCM using a pretty basic program call Scan9495. It was extremely easy to use. The issue I was running into was simply that whoever wired the car did not care to reconnect the serial data wire so it was cut in the middle of the wiring. That took a while of banging my head against the wall thinking I had done something wrong with the software. I grabbed a few screen shots of the data. What stands out to people. I expected to have several fault codes. Unfortunately I thought it would save the list of the codes but it did not. I will screen shot those while it is logging tomorrow.

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  6. #26
    Senior Member Carroll Shelby Supercharged111's Avatar
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    Are you open loop? Because fuel trim values of 128, IIRC, equate to 0% being added or subtracted, and LTFTs are applied regardless of temperature, MAP, or throttle position.
    RM CMC Director

  7. #27
    Your O2 sensors are wildly different as well. Might be normal, but I doubt it.
    CMC #50

  8. #28
    These are the DTCs that are showing. The program is setup to look at an automatic transmission so ignore the transmission codes. the two codes that stand out to me are 16 and 48. That is the MAF and Distributor code. I did put an extra MAF on that I had last week just in case, all of the connections internally appeared to be good. I am assuming that the distributor code is telling me that something is wrong with the OPTI. I ran it long enough this morning long enough to go into closed loop. I did notice that the O2 sensors look a bit off. LT and ST look like it is trying to compensate for something that is going on with bank 1 which is the same bank that we originally diagnosed as not firing on the back 3 cylinders. I will add a screen shot of the most recent scan.



    I noticed that it is hard to see. code 16 is "distributor ignition system (low resolution pulse)"
    Attached Images Attached Images
    Last edited by liquidroam; 07-08-2018 at 12:04 PM.

  9. #29
    This is when it was in closed loop

  10. #30
    ingore code 16. After clearing the codes it did not come back while running. Looks like it is down to the MAF. It is throwing the code and never changes from 470.62. I have two MAF sensors and both respond the same so I am assuming it is all in the wiring. Already found a broken ground wire for it but still getting the same feedback so i assuming there is more to the story.

    Update: I have the MAF situation taken care. The wiring turned out to be all sorts of jacked up and the connector it self was not in good shape. A wiggle of the 12v wire at the base of the connector and it shut the entire car off.so now the connector is replaced and functioning g properly along with a solid ground situation. The the LT looks good but the ST for Bank1 is all jacked up. I think it is a relsut of a bad O2 sensor. And so it is trying to compensate by running g really far. Send the injectors out to get cleaned and flow tested. And then testing the P2 situation when they get back.
    Last edited by liquidroam; 07-08-2018 at 07:07 PM.

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