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  1. #1
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    Default From bad to worse

    got my msd opti back from them for repair. said they rebuilt it as new. installed in car, ran fine for 30 mins then idled up on its own to 1700 rpm and died. wont restart, throws code 16, 42, and 51. i understand the code 16 is low res, but could code 42 and 51 be from the opti failure as well?
    2021 Charger Scat 392
    1994 Firebird Formula 381 stroker - Carrying the torch! - 9.90 @ 134.3mph on a 200 shot

    The wrench/driver for LTConvert's 94 Z28- Ellwein 383/LE Trickflows/ D1SC / CPT Ultra Pro Race 4L60E
    10.78 @ 125mph. Shooting for 9.99 for Frank Cahall!

  2. #2
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    DTC 42 sets when the PCM detects 84 crankshaft revolutions without any ignition circuit activity. The code only sets during cranking. There won't be any IC activity of there is no low res pulse from the Opti. Can also be caused by PCM failure.

    I'd be concerned about DTC 51.... that an EEPROM error due to a checksum error while running the program.
    SOLD - GONE TO A (VERY) GOOD HOME ! - 94 Formula A3+1: 381ci forged stroker - Callies Stealth, Oliver 5.85 billet rods, BME nitrous pistons / CNC LT4 heads / CC solid roller / TH400+GearVendors OD / 4.11 Strange 12-bolt / 300-shot N2O / Spohn Suspension / roll bar / MoTeC M48 Pro engine management system /a few other odds 'n ends.

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  4. #3
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    swapped icm. car runs, idle goes wherever it wants on its own, no codes though. car will idle up and down up and down by itself. no vacuum leaks
    2021 Charger Scat 392
    1994 Firebird Formula 381 stroker - Carrying the torch! - 9.90 @ 134.3mph on a 200 shot

    The wrench/driver for LTConvert's 94 Z28- Ellwein 383/LE Trickflows/ D1SC / CPT Ultra Pro Race 4L60E
    10.78 @ 125mph. Shooting for 9.99 for Frank Cahall!

  5. #4
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    @Injuneer back at it again. Swapped opti because car was breaking up on dyno, had a heavily used delco on it, took it back off and put a twice rebuilt msd on, car idles fine for 30 mins then starts revving up down up down up down.

    Mind you, before, i took the msd off and sent it out thinking it was to blame the first time this happened, i then put the delco on and had a icm failiure, another icm and it still acted up, finally a third icm and it calmed down. I think there is a ground or something screwed up by the icm or the icm pigtail is messed up.

    I have a datalog if you could take a look at it. Im not ready to blame the msd again since in february the delco did the same thing
    2021 Charger Scat 392
    1994 Firebird Formula 381 stroker - Carrying the torch! - 9.90 @ 134.3mph on a 200 shot

    The wrench/driver for LTConvert's 94 Z28- Ellwein 383/LE Trickflows/ D1SC / CPT Ultra Pro Race 4L60E
    10.78 @ 125mph. Shooting for 9.99 for Frank Cahall!

  6. #5
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    what is your iac doing while its surging up and down?

  7. #6
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    @blkchevyz flying open then coming back down, tach is jumping radically. iac counts jump from 48-53 to 110 hang for a 10 seconds or so and slowly walk back down then surge back up

    i have replaced the tps sensor as new, i have a delco icm on the way (amazon, $60 bones!), possibly gonna pick up another iac. i have one more used one laying around i could try
    Last edited by SSlowBoat; 05-19-2014 at 06:52 PM.
    2021 Charger Scat 392
    1994 Firebird Formula 381 stroker - Carrying the torch! - 9.90 @ 134.3mph on a 200 shot

    The wrench/driver for LTConvert's 94 Z28- Ellwein 383/LE Trickflows/ D1SC / CPT Ultra Pro Race 4L60E
    10.78 @ 125mph. Shooting for 9.99 for Frank Cahall!

  8. #7
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    I would personally pump the brakes on throwing parts at it, so you don't end up chasing your tail later.

    Have you datalogged over 30 minutes? Just wondering if this might be about the same time as your open/closed switch right now.
    '72 Nova "HadeSS"

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    Have you spaced the ICM off the head yet?

    97 T/A Ram Air Convt - 10.2@140 / 777rwhp - Forever Dyno Queen
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  10. #9
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    Quote Originally Posted by blackbirdws6 View Post
    Have you spaced the ICM off the head yet?
    icm has been spaced off the head since i bought the 94 3 years ago

    Quote Originally Posted by JCZNova View Post
    I would personally pump the brakes on throwing parts at it, so you don't end up chasing your tail later.

    Have you datalogged over 30 minutes? Just wondering if this might be about the same time as your open/closed switch right now.
    open/cold switch happens at around 5 minutes from stone cold. i have a 30 minute datalog, it didnt start doing it until after 20-25 minutes of idling. the biggest thing that stands out in the logs are the iac literally jumping from 37-40 counts up to 80-90 110-140 160 causing it to rev then slowly coming back down. i have a delco icm on the way and a delco iac as well

    fresh log, anyone with datamaster is more than welcome to take a look. i can email it straight to you and tell you where it starts
    2021 Charger Scat 392
    1994 Firebird Formula 381 stroker - Carrying the torch! - 9.90 @ 134.3mph on a 200 shot

    The wrench/driver for LTConvert's 94 Z28- Ellwein 383/LE Trickflows/ D1SC / CPT Ultra Pro Race 4L60E
    10.78 @ 125mph. Shooting for 9.99 for Frank Cahall!

  11. #10
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    Quote Originally Posted by TubbyFormy View Post
    @Injuneer ......

    I have a datalog if you could take a look at it. Im not ready to blame the msd again since in february the delco did the same thing
    Please e-mail to the address you should already have.
    SOLD - GONE TO A (VERY) GOOD HOME ! - 94 Formula A3+1: 381ci forged stroker - Callies Stealth, Oliver 5.85 billet rods, BME nitrous pistons / CNC LT4 heads / CC solid roller / TH400+GearVendors OD / 4.11 Strange 12-bolt / 300-shot N2O / Spohn Suspension / roll bar / MoTeC M48 Pro engine management system /a few other odds 'n ends.

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