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Thread: Stock 2006 gmc sierra 4.3l no start

  1. #1
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    Stock 2006 gmc sierra 4.3l no start

    So i am very new to hp tuners and as it turns out sometimes i need to learn the hard way not to just jump into something. i've spent days trying to fix this on my own, hope i didn't ruin anything so here goes. Truck is completely stock and ran good, young and dumb me was so excited with my new tuner mvpi2 pro, everything updated, net frame work, windows 7. So I know enough to get around (dangerous) and have a decent idea whats going on in the editor etc. So the changes i made to the ecu was i turned the shift light off. I also decided to enable fuel enrich at 3200rpm and no delay, idiot me didn't check the table so i bogged it and stalled it at 3200. It seemed to try and restart after (plugs were wet) so i popped air cleaner off to look things
    to look things over. I should have left it but silly me tried to reflash back to original, not sure what i did but i have no spark now. ive checked basics like power to icm and coil. on vcm scanner during an attempted start i don't see a injector duty cycle number and spark stays at 0 degrees. Im such an idiot lol was wayy to excited and goofed hard. I changed plugs and wires too because the plugs were ugly when i removed one. Also forgot to save original (i'm awesome) but change logs also say i only changed enrich and shift light. Any help would be appreciated
    SICKKKKKK 4.3 original modified.hptno start 4.3l friday.hpl
    Last edited by David Thiesen; 01-25-2019 at 05:33 PM. Reason: Don't know how to change to v6 forum oops

  2. #2
    Senior Tuner cobaltssoverbooster's Avatar
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    1) that file you posted has a 5200 rpm PE Delay with a 15 Second wait when triggered. pretty aggressive delay when you consider an entire 1/4 mile pass can be done in just about 15-17 seconds for a larger vehicle. (big issues.....ka boom)
    2) the PE commanded table looks good. i would keep that.
    3) the enrichment ramp in rate is set based on tip in afr results when transitioning to PE. i try to no let the transition zone to go much farther away from the 12.0-12.6 afr range.
    4) typically you don't target PE Enable by rpm but by MAP and TPS. Rpm is more for transition delay than anything else. typically disabled or set to a low rpm like 2200-2500 with a delay of less than .75 seconds. it is more common to see the delay disabled which is done by setting the delay rpm to 1500 and 0 seconds.

    5) (flashing) issues arise when the system voltage drops. i would try charging it up and keeping it on the charger while performing a "write entire" of the OEM file. If you read the OEM file and saved it.
    if this still causes a no start then you need to inspect some wiring and components. check for injector voltage when in run and cranking. The injectors use a 12 volt fused power supply. the is ecu switches the ground to trigger them so connect a ground to the battery (-) and check for battery voltage on the injector leads to verify a good power supply. if you have this then you need to inspect the sensors. the ecu uses both the cam and crank sensor for checking engine position. if one drops out, especially crank, then you can have a no injector or no coil issue. more common to see issues with the cam position sensor because its the sync sensor. the crank sensor is considered a home, cylinder reference sensor. the sync sensor tells the ecu the position of the cam so it knows which cycle the engine is on. without a sync signal the ecu is lost because the engine can be on target or 180* out.

    this is what i would start with.
    Last edited by cobaltssoverbooster; 01-25-2019 at 08:57 PM.
    2000 Ford Mustang - Top Sportsman

  3. #3
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    Awesome, thanks for the info on the PE, that makes sense, ill try to write entire and ill check the components mentioned. I just plugged my standard code reader in to double check for codes in case i was missing something and it came up with p0351 ignition coil A primary/Secondary circuit. wondering if i bumped something, although ive checked the connectors on cam sensor icm and coil, they look good. Ill let the battery charge up fully and try the write that way. Thank you very much for your response i appreciate it!

  4. #4
    Senior Tuner cobaltssoverbooster's Avatar
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    its always a possibility. check mechanical since you have a code and try again. if no, go for reflash to OEM. then last check on those key sensors.
    2000 Ford Mustang - Top Sportsman

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    Alright, sounds good. Ill check those things tomorrow

  6. #6
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    Some diagnostic info if you need.
    Attached Files Attached Files
    Last edited by DGS; 01-26-2019 at 12:03 AM.

  7. #7
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    Oh wow that's awesome, that's incredibly helpful. Thank you!

  8. #8
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    Good Luck. Advise on how it works out.

  9. #9
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    will do!

  10. #10
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    Ok so i checked the icm for ac pulsed voltage voltage, it is pulsing at 2.5v ac which is within range (1-4v in manual) so it should be sending pulsed ground to the coil. which it is not, power and ground are good to icm and power is good at the coil (full 12v while cranking). Im suspecting the icm so i'm going to change it. if it's getting a pulsed voltage it should be sparking i think? Im gonna throw a part at it now.

  11. #11
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    Just to let you know it's fixed! It was the ICM, replaced and fired right up, $15 from the auto wrecker! Thanks again guys!