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Thread: Injector Wiring Help Please

  1. #1
    Join Date
    May 2012
    Location
    West Sussex,UK .
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    Default Injector Wiring Help Please

    Hi, I am helping a friend of mine install a Holley 950 Commander system on his 1951 Oldsmobile Rocket 303ci engine using 3 Retrotek throttle bodies on a Tri-Power type intake.
    (I have some experience fitting Holley Stealth Ram 950 system to my 57 Chevy and a couple of other systems to friends cars).
    The throttle bodies each have 2 48lb/hr injectors fitted like shown in the picture below:

    Click image for larger version. 

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    The 3 throttle bodies are fitted to the intake as shown below:

    Click image for larger version. 

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    We ordered the Holley Commander 950 Universal V6 kit #950-110 assuming it would come with an injector harness wired for 6 injectors but it actually came with an 8 injector harness.
    We removed the 2 injector plugs furthest away from the 5 pin multi-plug (for the front 2 cylinders) leaving us with 6 plugs to fit to the 6 injectors and have used the Holley wideband O2 sensor kit #534-197.
    The distributor is stock with Pertronix electronic module fitted and timing is not controlled by the ECU.

    We've had the engine running but have noticed that there are fuel distribution issues in that the front 4 plugs are lean but the rear 4 plugs are very sooty.
    It looks like the center and rear injectors are firing more frequently than the 2 front injectors giving a lean misfire condition at the front of the engine.
    I used my PicoScope to check that all 6 injectors are firing correctly and they are, they each draw about 2 amps current and show a good trace.

    I have recently read that the 8 injector harness would have fired the injectors in pairs diagonally opposite each other, i.e. drivers side front 2 and passenger side rear 2 all together, is this so?

    Can the injector harness be rewired so that the 3 injectors on the drivers side all fire together and then all 3 injectors on the passenger side all fire together and so give consistent fuel distribution?

    Thanks for your time, Martin.

  2. #2
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    22,685

    Default

    See if this forum thread helps you:
    http://forums.holley.com/showthread....=2141#post2141
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 11.8:1 comp, TFS R-Series intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 160A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, M4602G aluminum driveshaft, FRPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 tires.

  3. #3
    Join Date
    May 2012
    Location
    West Sussex,UK .
    Posts
    4

    Default

    Hi Danny, thanks for the link, all the wiring checks out OK.

    We have removed the injectors to check for any debris in the basket filters and found some
    in the front 2 injectors. So we'll get them all checked on ASNU machine for spray pattern and flow.

    Regards, Martin.

  4. #4
    Join Date
    Dec 2009
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    Connecticut
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    Quote Originally Posted by av8 View Post
    So we'll get them all checked on ASNU machine for spray pattern and flow.
    That's a good idea. Sometimes, people are surprised with the test results.
    https://www.youtube.com/user/rbanner100/videos (Fuel Injector Testing)
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 11.8:1 comp, TFS R-Series intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 160A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, M4602G aluminum driveshaft, FRPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 tires.

  5. #5
    Join Date
    May 2012
    Location
    West Sussex,UK .
    Posts
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    Default

    The injectors all tested OK and now have new filter baskets fitted.
    Now looking into possible fuel flow restriction to front throttle body, will post any further info.

  6. #6
    Join Date
    May 2012
    Location
    West Sussex,UK .
    Posts
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    Default

    Hi. We found that the fuel pressure regulator was plumbed in before the fuel rail and so we reckon that the 2 injectors at the front of the engine were low on fuel pressure.
    Regulator is now relocated correctly after the fuel rail, exhaust header temperatures all pretty even now and it's tuning in OK. Martin.

  7. #7
    Join Date
    Dec 2009
    Location
    Connecticut
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    Quote Originally Posted by av8 View Post
    We found that the fuel pressure regulator was plumbed in before the fuel rail...
    Ahh...an installation error. Those can be the worst to troubleshoot. Glad you found it.
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 11.8:1 comp, TFS R-Series intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 160A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, M4602G aluminum driveshaft, FRPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 tires.

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