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Thread: injection issue 7mge need guru help.

  1. #1
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    Default injection issue 7mge need guru help.

    the problem
    The car is missing, #5 injector does not inject gas. I have checked spark its good. engine fault code was 25. I have verified all other cylinders work. I have verified I have 12volts between red wire and ground with ignition on. on injector #5. we did not get connectivity between ppine of white wire and main wire( where it is spliced into the wiring harness).

    what I have done last

    We replaced the section of wire that is tied into number 3 injector to include new female pin ( white wire). We put every thing back together and still number 5 does not get gas. I de pinned the 12vt side (red wire) and ran 12vlts to the injector when the car was running no change. We then (to verify we hand a good wire from # 5 injector to the ECU did a ohms test and it is good from the pin on the injector to the ecu. the injector works if I run wires direct to I have spark at that cylinder. I have to assume that if #3 injector is working fine that it is not the ECU. What am I missing? What Else could it be? HELP!

    a little back history

    We this summer replaced the engine with a JDM engine after original went out in May. this car had sat for 4 years and the PO did a bad job on a rebuild that he never finished. we got it last spring and put it back together and replace tons of pars. I have read the TSRM and used the wiring diagram to help me trouble shoot the issue. I have to long threads on Supra forum about this project. I am at a lost as to what else I can do. and son that is loosing hope that he will ever drive this car as it should drive.

    thanks for help.

  2. #2
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    Default Re: injection issue 7mge need guru help.

    How are you determining that the injector is not firing? Noid light? Audio Scope? Inspecting Spark Plug? Other?
    Have you swapped injectors around on the rail to see if the misfire follows the injector or stays on #5?
    This will give you a clue as to what to check next.

    Have you checked the resistance of each injector yet and compared against spec? (unplugged from harness)
    Spec- 2.0 - 3.8Ω (For GTE engine)

    Code 25 is for an A/F Lean Condition
    Could be multiple issues:
    http://www.cygnusx1.net/Supra/TechTi...ror_codes.aspx
    I rebuild / upgrade Supra Differentials - PM me for more information.

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  3. #3
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    Default Re: injection issue 7mge need guru help.

    Quote Originally Posted by Piratetip View Post
    How are you determining that the injector is not firing? Noid light? Audio Scope? Inspecting Spark Plug? Other?
    Have you swapped injectors around on the rail to see if the misfire follows the injector or stays on #5?
    This will give you a clue as to what to check next.

    Have you checked the resistance of each injector yet and compared against spec? (unplugged from harness)
    Spec- 2.0 - 3.8Ω (For GTE engine)

    Code 25 is for an A/F Lean Condition
    Could be multiple issues:
    http://www.cygnusx1.net/Supra/TechTi...ror_codes.aspx
    I have a non turbo

  4. #4
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    Default Re: injection issue 7mge need guru help.

    Ok I put this in the wrong section my bad. I checked all injectors before putting them into the engine. All new seals. I can pull the plug wire off of 5 and the car does not change how it runs. When I pull the plug on the rest of the cylinders the car misses more. I confirmed number 5 cylinder has spark. New cap rotor and plugs. I even tried a different plug no change. I had found that I didnt have connectivity on the white wire to number 5. 5 and 3 share the same pin on the ECU. 3 has connectivity and is working. I pulled and u did the wiring harness saw where the white wire on 5 injector was spliced. No connectivity so I replaced. I really thought we had found the problem. Put it all back together no change. I can flood the cylinder with gas if I run a separate wire for the white wire. It act as ground that it should be getting from the ECU. That tells me injector is working. It get a higher reading for ohms across the injector but the others to next to it read the same.

  5. #5
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    Default Re: injection issue 7mge need guru help.

    This question still applies no matter what engine you have.

    Have you swapped injectors around on the rail to see if the misfire follows the injector or stays on #5?
    This will give you a clue as to what to check next.
    I rebuild / upgrade Supra Differentials - PM me for more information.

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  6. #6
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    Default Re: injection issue 7mge need guru help.

    Check for fuel on the spark plug.
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  7. #7
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    Default Re: injection issue 7mge need guru help.

    Quote Originally Posted by Piratetip View Post
    This question still applies no matter what engine you have.

    Have you swapped injectors around on the rail to see if the misfire follows the injector or stays on #5?
    This will give you a clue as to what to check next.
    I have not swapped around injectors. The injectors were cleaned and I tested them before putting them in. If I can get fuel to go into the cylinder by connecting it directly to ground it works right?

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    Default Re: injection issue 7mge need guru help.

    Quote Originally Posted by Nick M View Post
    Check for fuel on the spark plug.
    I will check for fuel on the plug. Would this mean it is over squirting?

  9. #9
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    Default Re: injection issue 7mge need guru help.

    Quote Originally Posted by 1933beer View Post
    I have not swapped around injectors. The injectors were cleaned and I tested them before putting them in. If I can get fuel to go into the cylinder by connecting it directly to ground it works right?
    No, it might not be able to open in the ms time commanded by the ECU.
    Could be a sticky pintle, weak / damaged coil, mismatched Ω between 3 & 5, or other issues.

    Making assumptions for a diagnosis is never a good idea.

    What are each individual injectors Ohm readings?
    1-
    2-
    3-
    4-
    5-
    6-

    7M-GE wiring TCCS
    http://www.cygnusx1.net/Supra/Librar...px?S=Main&P=54
    I rebuild / upgrade Supra Differentials - PM me for more information.

    1 Piece Driveshaft Information
    Critical Speed Calculator

  10. #10
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    Default Re: injection issue 7mge need guru help.

    I don't know how he got 18 before I do know that the digital meter I had broke and the old analog he used was giving him 10 -12. I picked up a new cheap meter and it gave me the readings below. 5 was different but not by much


    Quote Originally Posted by Piratetip View Post
    No, it might not be able to open in the ms time commanded by the ECU.
    Could be a sticky pintle, weak / damaged coil, mismatched Ω between 3 & 5, or other issues.

    Making assumptions for a diagnosis is never a good idea.

    What are each individual injectors Ohm readings?
    1- 3.5
    2- 3.5
    3- 3.5
    4- can't get to
    5- 4.1
    6- 3.6

    7M-GE wiring TCCS
    http://www.cygnusx1.net/Supra/Librar...px?S=Main&P=54
    We put on a new O2 sensor and it improved how the car runs under load. so I even put in our other Amf meter. I put another plug in and no change we ran the car a few miles pulled the plug and the number 6 plug. 6 was hot and 5 was noticeably cooler. I could grab it with bear hands 6 not. at idle the car runs nice just the slight miss. I have new injector connectors on there way. I should get them on the 31. I will de pin #5 and replace connector. I don't think it will fix. if not we will pull the injector and replace with another one we have. while we are in there for the 5th time we will replace the rest of the connectors.
    Last edited by 1933beer; August 30th, 2017 at 02:32 PM.

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