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OBD II Computer Codes Updated

Discussion in 'The Garage' started by ChevyHuny, Oct 21, 2002.

  1. ChevyHuny

    ChevyHuny 1/2 ton status

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    <font color="blue"> First off thank you Twiz (Eric) and ntaj*ep(Aaron) for your help with my computer codes for my 96 pickup. Just to refresh what was going on, I was getting a MAF sensor code and my idle was up and down, including no power till 10mph. We followed your directions and I thought I would let you know what happend and see if you or anyone else has any thoughts.

    First with the meter scan, we found out that the pink (ignition power) wire to the Maf sensor was bad. So we jumped it off of a good power source and got a great reading. Turned the truck on and no up and down idle, no dying, etc.... Problem with that fixed. However it is still doing the no power until 10mph and also is missing.

    So we did another computer scan. Its got a new code. A P1345, which is a GM specific code. <font color="red"> Code definition is : "P1345 GM Camshaft To Crankshaft Position Correlation Fault" . </font color>

    So pulled the spark plugs and #1 cylinder looks brand new. . It has been driven around at least 15 miles and ALL the other plugs show wear. We checked and its getting spark on the wire and plug.

    <font color="red"> ******UPDATE*******</font color>
    We tested the injectors resistance(at the posts), they were all equal.
    We then tested the voltage going across the injector circuit with key on. All were about 32 mv except didnt seem to have much on number 1 circuit. Thought maybe it was the wire then so found the wire leading to the injector on the ecm and tested the continuity and it was good.

    Then thought maybe the ecm was messin it up so plugged in the other one and hooked everything up and started it with no difference.
    Then looked at plug in number one and found evidence of firing. now think the timing may be the problem since its now obvious that the miss is not isolated to number one.

    Tomorrows plans are to check the compression, and timing (again). We are trying to figure out if the timming is retarded or too advanced.

    Anyone seen Twiz around??


    Thanks in Advance for any thoughts, /forums/images/graemlins/smile.gif
    Mandy</font color>
     
  2. TopOff

    TopOff 1/2 ton status

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    Re: OBD II Computer Codes Chapter 2

    It sounds like your crank sensor and your ignition are not matching up.

    This happened on my friends 97 Tahoe. We figured it was a tooth off, we reset the the tooth. It ran better, but we still got the code. Finally took it to the dealer... $150 later, they reset the timing on the right distributor tooth. It was off still another tooth!

    Oh well.

    Good luck.
     
  3. ChevyHuny

    ChevyHuny 1/2 ton status

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    Re: OBD II Computer Codes Chapter 2

    </font><blockquote><font class="small">In reply to:</font><hr />
    This happened on my friends 97 Tahoe

    [/ QUOTE ]

    /forums/images/graemlins/smile.gif Thanks, Which part happend? The code, the no power until 10MPH, etc...
     
  4. TopOff

    TopOff 1/2 ton status

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    Re: OBD II Computer Codes Chapter 2

    Sorry the code. But it did appear to work fine. Every once in a while it got a miss that we could feel.
     
  5. ChevyHuny

    ChevyHuny 1/2 ton status

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    Re: OBD II Computer Codes Chapter 2

    I'll recheck that. Thank you
     
  6. TopOff

    TopOff 1/2 ton status

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    Re: OBD II Computer Codes Chapter 2

    Were you able to check the TDC sensor(s)?

    What about the ignition timing? (My friend and I couldn't find this either).

    Ijust found out he had the injectors cleaned. A shop suggested running some cleaner through the injectors, and some cleaner in the tank. He LOVES his Tahoe again... he says it no longer pings, and he is getting much better gas mileage.

    I hope you found your problem too.
     
  7. ChevyHuny

    ChevyHuny 1/2 ton status

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    Re: OBD II Computer Codes Chapter 2

    Thanks /forums/images/graemlins/smile.gif I had put a can of good injector cleaner through the tank and injectors shortly after it started the first time. I have been running good gas in it too. It has been timed more times then a could count lol.

    Updated on first post.
     
  8. ntaj*ep

    ntaj*ep 1/2 ton status

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    That is abit strange. Maybe the valves are sticking abit? Can you determine which cyl.? I assume its #1 the way yer post sounded.
    I need to think about this.
     
  9. ChevyHuny

    ChevyHuny 1/2 ton status

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    I do not know why but #1 Spark plug is finally fireing. Pulled the plug tonight and it was carboned up and looked like the others. One more thing checked off the list.

    I thought maybe this new code would be helpful but it is not yet. We are doing a compression check tomorrow evening, along with rechecking the timing. I will post what the results are, maybe that will help? If there is anything else you think I should check I will be on before I go do those things in the evening.

    Thank you very much for any help. Hopfully we will find some more answers with tomorrows results.
     
  10. ntaj*ep

    ntaj*ep 1/2 ton status

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    I'm not sure where the crank/cam sensors are on the motor. Twis would though. If theres a reluctor ring that maybe damaged as well. I think that code can be set for tiny fluctuations in the crank or cam. /forums/images/graemlins/confused.gif like if a valve was hanging for like a mili mili sec.(if that exsists, lol)
    Still thinking /forums/images/graemlins/thumb.gif
     
  11. Twiz

    Twiz 1/2 ton status

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    Hello--

    Glad you fixed the MAF problem, pretty easy when you have something to work off of, isn't it?


    P1345, CKP to CMP fault.

    This DTC detirmins if the Distributor is installed incorrectly, or if there is exsessive lash between the crank and cam/distrubutor, possibly indicateing a worn timeing chain.

    The VCM (or ECM/PCM) is "looking" for the cam-shaft position sensor (CMP) signal as it relates to the Crankshaft position (CKP) signal. If the CMP signal does not arive within a "window of opritunity", then the VCM sets a DTC 1345. (does that make sence?)


    Possible causes:
    - Loose dist. hold-down clamp (allowing the dist. to walk)
    - Loose CMP sensor, inside the dist., causeing an irratic signal
    - Improperly installed Distributor. One tooth advanced or retatertd (as Topoff said)
    - Worn dist. rotor, causeing an irratic CMP signal
    - Worn timeing chain/gears, ect..

    In this case, I would suspect the dist. is off by a tooth, or incorrectly timed. The only way I know of to "time" a Vortec engine is with a Tech2. Useing the Tech2, you adjust the timeing to set the CMP to "0".



    Thats about all I have, "Drivability" is NOT my thing, I'm a "Genneral area" kinda guy.

    Hope that helps some.
     
  12. ntaj*ep

    ntaj*ep 1/2 ton status

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    Does the timing set have the nylon inserts in them? On the teeth.
     
  13. ChevyHuny

    ChevyHuny 1/2 ton status

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    Well, tonight the person I was supposed to get the compression checker from was not home and I didn't get out there till late. So the only thing that was done was retard the distributer a tooth. The truck didn't like that. I can only explain the noise it made as Blugh blah blah bloo. Then it got too dark and too cold so hopefully tomorrow we can give it another shot.

    I am printing again what you have said twiz and will take it with me tomorrow. I appreciate all the help you guys have given me. Hopefully we will get farther tomorrow.
     
  14. jimbo92

    jimbo92 Newbie

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    when u did all this where did u pull power for the MAF? mine is doing the same thing and the only thing that could keep it from running it is the computer or a short, also what did u find about the cam position sensor? my 98 Z71 has the exact same symtpoms
     

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