Distributor installation problem

Discussion in '96+ Vortec Performance + Computer Swaps' started by homeslice, Nov 5, 2018.

  1. df2x4

    df2x4 Domestics only.

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    The PCMs changed physically in '98 to some degree as they have an additional connector compared to the '96-'97 units. Maybe there were some internal changes that would explain the differences you're seeing in the manuals.
     
  2. homeslice

    homeslice Newbie

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    Just want to make sure I understand. Are you saying that the '96 manual provides a tolerance of +/- 20 degrees from 0, but '97-'98 manual has tolerance of +/- 2 degrees ?
     
  3. delta_p

    delta_p OBS Enthusiast

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    For the L31 5.7L, The 96 has 0 +/- 20, the 97 has 0 +/- 2, and the 98 has 0 +/- 2. They all want 0 even. All of those are engine at temp, idling under closed loop, closed throttle, park/neutral. This has to be a misprint in the '96?

    If you go to each section on the DTC P1345 which would be the result if the offset is out of tolerance, only the '98 goes into detail about the narrow tolerance window and has a specific set of test steps performed in the trouble shooting table about checking the retard offset when RPM raised to 2000. Also says the engine will run but 0 can not be obtained.

    In both the 96 and 97 the DTC P1345 it states the DTC used to determine if the distributor is installed correctly or there is a mechanical malfunction. In '98 states the DTC monitors the CKP and CMP signals to determine if they are sychronized, if both signals are not observed by the PCM/VCM within a narrow time window, the VCM will throw the code.

    I am just thinking my '96 isn't using the same importance on the signal as the '98 because i know my offset is out of tolerance and there is no code with good driveability and idle.

    I have become interested in OBDII as a hobby and particularly on these 3 years GM C/K's., this is the reason i have the 3 manuals and use my '96 as a guinea pig. Eventually, I am going to take my scantool and run out the distributor in both directions until the code trips. I am just not sure this DTC on offset has anything to with driveability and doesn't seem so by reading the manuals.
     
  4. homeslice

    homeslice Newbie

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    Interesting. for what its worth, when mine was running at -26 degrees (which it did for a year); it never threw a code, and seemed to run fine.

    With the offset at -26 degrees, Blackbear let me know the dist was not installed correctly and timing was limited to 35 degrees; while the engine wants 40-42 degrees.

    So, I 'm wondering if running at -4 or +7 degrees offset will allow me to get that remaining 5-7 degrees of timing. I think I will send BB another data log at -4 or +7 offset and see what they say. I may just be chasing a non issue.
     
    Last edited: Nov 6, 2018
  5. homeslice

    homeslice Newbie

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    Well, I finally got my 0 degrees offset. I ended up grinding some material off the front bolt hole boss of the distributor body, which gave me a bit of additional travel to hit 0. With the summit distributor it seems that neither the Aloicious nor East302's procedure is 100% correct for the 5.7L. At the end of the day I kind of figured out that when the distributor is finally installed, the cap rotor pointer needs to be pointing at the cyl #1 post on the cap. The distributor body has a little point with a little 8 stamped on it at this location. Thanks again for the assistance.
     
  6. east302

    east302 I'm Awesome

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    Glad you got it sorted out, thanks for posting an update.


    Sent from my iPhone using Tapatalk
     
  7. big_mike

    big_mike I'm Awesome

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    Just for extra info, I was getting a cam position sensor code on my 99 tahoe which was built in 98. I replaced the sensor in the distributor and it wouldn't start, would just turn over and pop in the exhaust, obviously out of time. Although it ran with the original sensor just threw the code. Took it to a mechanic and he said it was 26* outta time, he adjusted it and it ran fine.

    Weird it would run on the stock sensor and only pop a code but with a brand new sensor it wouldn't even start. After reading your post it has me wondering WTF this crap black box has going on in it, lol. Makes me wanna do the 411 swap even sooner.
     
  8. 5vortec7

    5vortec7 I'm Awesome

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    I had the same problem you were describing after doing my spider injector upgrade and found out I was a tooth off. Couldn’t get the dizzy turned enough without obstruction from the drivers side valve cover if I remember correctly. Had to pull the dizzy and reach down with a long screwdriver and turn the slot/shaft a few degrees in the opposite direction. I got lucky and turned it just enough to get the clearance I needed.
     

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