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Thread: LQ4 with LS2 Intake and Injectors - Will Not Start

  1. #1

    SOLVED - LQ4 with LS2 Intake and Injectors - Will Not Start

    Chevelle Tuned Min Inject Change.hpt

    Tune is above. I have a 2004 LQ4 that I just installed a LS2 intake and injectors on.

    I updated the tune to have the injector data. I upload the tune, go to crank it up and the engine just turns over and over without a hint of starting.

    Any tips?

    I change the injector flow rate vs KPA, Short Pulse Limit, Short Pulse Adder, Min Injector Pulse, and Default Injector Pulse. I did not change anything else in the tune.

    I have fuel pressure at the rail

    IT IS NOT GETTING FUEL
    - I checked this by spraying starting fluid into the TB, cranked it over and it fired up right away then died after a couple seconds.

    UPDATE - The injectors ARE getting power. So this must be due to the tune? unless all of my injectors are bad, which... blah

    SOLUTION:
    I pulled the fuel rail off with injectors attached, put some paper underneath everything to see if fuel was coming out of the injectors - cranked it over and saw NO fuel was coming out. So I know they are getting power, but none are firing.

    I used a needle and pierced into each ground wire for the injector and grounded that wire for 1 second intervals - initially they did not spray, but after the 2nd interval they started spraying perfectly. I did this to all injectors - re-did the paper test and saw all were spraying fuel now.

    Bolted fuel rail back on, cranked the engine and it fired right up no issues at all.

    Summary: Fuel injectors must have been sitting around for a while, just needed a kick to get back going
    Last edited by TXjeepTJ; 06-26-2015 at 10:23 AM.

  2. #2
    IMG_1326.jpg

    According to my wide band, it's not getting any fuel. Engine not cranking - Lambda is 1.3, engine cranking lambda is at 1.3 or around 1.29.

    Could the plug adapters I bought for the injectors be wired wrong? The Red wire is connected to pink from the wiring harness - if anyone knows what color wire should be closest to the push/clip part of the injector, that would be awesome haha

  3. #3
    Advanced Tuner
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    I'd this a new build our was it running previously?

  4. #4
    Running previously, really good too lol...

  5. #5
    CONFIRMED - it is NOT getting fuel. I sprayed some starting fluid into the engine and cranked it over and it fired right up for a couple seconds then died.

  6. #6
    Potential Tuner
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    Quote Originally Posted by TXjeepTJ View Post
    IMG_1326.jpg

    According to my wide band, it's not getting any fuel. Engine not cranking - Lambda is 1.3, engine cranking lambda is at 1.3 or around 1.29.

    Could the plug adapters I bought for the injectors be wired wrong? The Red wire is connected to pink from the wiring harness - if anyone knows what color wire should be closest to the push/clip part of the injector, that would be awesome haha

    FWIW: The solid pink wire on the stock injector harness is on Accessory power from the vehicle. The other various color is the ground signal from the PCM.

  7. #7
    Tuner POWERZONE's Avatar
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    Make sure you have continuity from the fuel pump relay to the fuel pump.
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  8. #8
    Yup, continuity is good..

    Anyone know what the mass air pressure (MAP) should be at during cranking?

  9. #9
    Quote Originally Posted by TXjeepTJ View Post
    Yup, continuity is good..

    Anyone know what the mass air pressure (MAP) should be at during cranking?
    I think I found the issue. The adapter I got to adapt my LQ4 TB to the LS2 intake has a spot that is not sealed. The gasket on the adapter does not seal off half of the top section of the TB - leaving half of this area on the TB open to the atmosphere.. see pic
    Capture.JPG
    Last edited by TXjeepTJ; 06-25-2015 at 11:47 PM.

  10. #10
    Issue solved, see first post for solution

  11. #11
    Potential Tuner
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    Thank you for the post TXJEEPTJ. I have the same issues. I am going to try that. I would have never thought of jump starting the injectors like you described.
    5.3L Twin Turbo, 40L60E, 2WD Truck underconstruction