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code 42 problems updateed !!!

Discussion in 'The Injection Section' started by sweetk30, Mar 18, 2007.

  1. sweetk30

    sweetk30 professional hooker Premium Member

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    i got this truck running after it sat for over 7 years. 87 tbi 350 . it has a new motor to it with all electronics from the 88 350 it sat for 2 years. all fired up and run good for few days. then it starts to throw code 42. i check it and then check timing. its at zero with wire pulled .

    i have a new module in dist as it was orignal and yucky looking. so when motor was swaped and tuned up on install i swaped in new mod. it ran perfect for few days. then started this crap.

    now i swaped in newer good computer with 350 chip in it. both same service #s on them. it still does the same thing. and some times it takes 10 min to pop light on and set code. others its 1min or less from start up. this is all cold or hot motor.

    other day was plowing and it would act like it lost fuel and die. to start it i had to floor it and clean it out. and the more i drive it now the more i dont trust it. it starts to buck and die when driving it.

    just looking for a good idea as i am ready to start figuring this out.
     
    Last edited: Mar 31, 2007
  2. dyeager535

    dyeager535 1 ton status Premium Member

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  3. sweetk30

    sweetk30 professional hooker Premium Member

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  4. Russell

    Russell LB7 Tahoe Status Premium Member GMOTM Winner

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    We'll fix that problem then!

    [​IMG]

    [​IMG]
     
  5. Thunder

    Thunder 3/4 ton status

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    Many times for a code 42 It is the magnetic pick up coil. Missing under a load is common symptom of a bad pick up coil. Pull the leads off (2 wire plug usually white and green) the dist module and put an ohm meter between the wires to read thru the coil. it should read 500-1500 ohms. if not replace. You have to pull the dist to replace.
    Also Check all connections from dist to ECM. Check grounds.

    It is possible that the new module you put in died. A module can thro a 42 also. It is best to use only GM modules.
    Did you put plenty of that white dielectric grease on the back of the module?
     
  6. dyeager535

    dyeager535 1 ton status Premium Member

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    If yer gonna own OBD1 GM EFI V8 rigs, you gotta be a member there. Almost guaranteed, SOMEONE has had your problem before over there. :)

    You've had it apart, but it never hurts to make sure the connection is good as well. I don't know what is up with those pickup coil leads, but all the old distributors I've seen have green stuff all over them. Not sure if that's some sort of old dielectric that GM put on from the factory, or if it's some sort of corrosion, but I can't see it helping make good contact as it is.

    Had a code 36 (MAF sensor burnoff issue) randomly pop up the other day after replacing the injectors, (tore top of engine apart) so I shut it off, cleared codes, reseated the MAF connector, and no more problem. 4 pin connection, about 4 or 5 possible MAF codes, and it throws one oddball lol. :rolleyes:

    Similar issue with an intermittent (for awhile) code 33, followed troubleshooting chart multiple times, said ECM or MAF was bad. Inspecting the components as you should, noticed one of the ECM connector terminals for the MAF was broken, and wouldn't keep contact with the ECM pin. Fixed the connector, no more problem.
     
  7. sweetk30

    sweetk30 professional hooker Premium Member

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    well i took just a look at the innereds of the dist. and found some green in the 2 wire plug. then the copper dust shield was almost frozen to the pickup coil body. also the top 8 point star area was kind of rusty and puffing up a bit. so i dug threw my collection of 3 tbi dist units. and only 1 was of any real use. and that one was like new all the way threw. so i pulled the module and cleaned all parts up and re slimed with the grease and installed it and set timing and 1hr drivin time so far with no problems.

    will let you guys know if one pops up. thanks so far guys.
     

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