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Thread: Injectors not firing sometimes during engine cranking, both cold & hot starts.

  1. #1

    Default Injectors not firing sometimes during engine cranking, both cold & hot starts.

    I've been running the Dominator on my car for two years with no issues. The car sat for a year while I did some interior work. Currently, the car will sometimes fire right up after a few seconds of cranking, but sometimes it will crank until the battery goes dead with no start. I've narrowed it down to the injectors not firing using a noid light on my injector plug. I have spark and I'm seeing cranking RPM (approximately 125 RPM or so) on my laptop. All sensor inputs are showing valid real-time readings. The software seems to be fine. I'm running V4 software. I'm baffled, how can the car start right up sometimes and other times the car won't start because the injectors are not firing? Sometimes I will try to start it 3 or 4 times with no injector firing, then on the very next try, it fires right up? Any ideas? I'm going to recheck all my grounds, then if all else fails, I will pull the harness out and check all the wires to make sure nothing looks shady. I could see a wiring issue if the car would never start, but how can this issue be intermittent? This happens sometimes when the car is cold and when it is hot. Once the engine is running though, it runs great and never stalls or misses a beat?

  2. #2
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    21,574

    Default

    I highly suggest recording & reviewing a datalog of this no start occurrence.

    Originally Posted by Danny Cabral
    Quick Datalogger Information:
    Always provide data, not just symptoms. Is the AFR & ignition timing optimized? Overlay the datalog onto your Global File.
    Ensure the Target A/F Ratio table is properly programmed for your engine. Ensure the ECU is "Learning" (Learn Table LINK).
    Scroll through the datalog to the problem area. Then look exactly where this happens on the Base Fuel & Timing Tables. Scrutinize:
    RPM, MAP, MAT, TPS, CTS, IAC, Target AFR, AFR Left, CL Comp, Ignition Timing, Duty Cycle, Fuel Flow, Fuel Pressure & Battery.

    Using the Holley EFI software (LINK), look at where the live cursor moves to during this occurrence, and
    manually tune that area of the Base Fuel Table (enrich or lean) & Base Timing Table (optimize ignition timing).


    I find the most helpful datalog function, is overlaying the datalog on your Global File.
    I'm in the habit of using the datalog Overlay feature every time I review a datalog.
    Click on "Datalog" (on the top Toolbar), "Activate Overlay", then "Open Data Log".
    You can literally "playback" a recorded event, and watch it as it happened on any screen.
    Minimize (shrink) the datalog window, and move it to the bottom of any Global File screen.
    Then click & scroll anywhere on the datalog, and watch it playback on your Global File (EFI software).
    http://documents.holley.com/techlibr...9r10543rev.pdf (Holley EFI Datalogger Instructions)
    https://forums.holley.com/showthread...s-amp-Datalogs (Datalog & System Log Information - Read "NOTES")
    https://www.youtube.com/watch?v=iqHO...C6FEA0BB99AF17 (How To Record & Email A Datalog)
    https://www.youtube.com/watch?v=q7OZUXLRS1Q (How To Record A System Log & Diagnose A No-Start Condition)
    https://forums.holley.com/showthread...7531#post77531 (Closed Loop Datalog Tuning - Posts #2, #4 & #6)
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: Dominator MPFI & DIS, A/C, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/X-pipe/shorty headers, 100HP progressive dry direct-port NOS, 160A 3G alternator, Optima Red battery, LenTech Strip Terminator wide-ratio AOD/2700 RPM converter, 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

    Default

    OK, I performed a datalog while cranking the engine. What am I looking for? I see 120+ RPM, about 9 msec Inj PW, my fuel is on a manual switch and I witnessed 43 psi on the gauge. I have spark, I have 12.1 volts on the green pump wire, I have 12.1 volts at the injectors, but I have no ground pulse at the injector harness while cranking. My starter is pulling the battery voltage down to about 11 volts during cranking, is this the issue? Will the Holley not ground the injectors if the battery voltage is too low? I'll start checking my injector wiring harness for issues and then trace it back to the ECU. I'm considering a new starter as well. I've already swapped my other Holley HP car battery into the car with no change. The Holley HP car fires right up, every time!
    '93 Mustang LX Sedan, Holley Dominator EFI, Twin 66 mm, 347, TH 400, 3.27s - 8.54 @ 162 through the tailpipes on DRs
    '91 Mustang LX Sedan, Holley HP EFI, 410 with Novi 2000, 5 speed, 3.73s - tire destroyer!
    Coming this Fall, 2019 Mustang GT, A10 Auto, 3.0L Whipple - 9 second cruiser?

  4. #4
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    21,574

    Default

    Quote Originally Posted by Twin66mmTurboLX View Post
    My starter is pulling the battery voltage down to about 11 volts during cranking, is this the issue?
    No, that's actually pretty good for cranking voltage drop.

    ...but I have no ground pulse at the injector harness while cranking. I'll start checking my injector wiring harness for issues and then trace it back to the ECU.
    http://forums.holley.com/showthread....9623#post69623 (System Relay & Injector Wiring Troubleshooting)
    http://forums.holley.com/showthread....5760#post45760 (Scroll down to "Typical No-Start Checks".)
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: Dominator MPFI & DIS, A/C, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/X-pipe/shorty headers, 100HP progressive dry direct-port NOS, 160A 3G alternator, Optima Red battery, LenTech Strip Terminator wide-ratio AOD/2700 RPM converter, 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

    Default

    I've made no changes since my Datalog to the car, and I just tried to start it again and it fired right up? What's going on with this thing? Intermittent problems are by far the worst!
    '93 Mustang LX Sedan, Holley Dominator EFI, Twin 66 mm, 347, TH 400, 3.27s - 8.54 @ 162 through the tailpipes on DRs
    '91 Mustang LX Sedan, Holley HP EFI, 410 with Novi 2000, 5 speed, 3.73s - tire destroyer!
    Coming this Fall, 2019 Mustang GT, A10 Auto, 3.0L Whipple - 9 second cruiser?

  6. #6
    Join Date
    Nov 2014
    Location
    Ont. Canada
    Posts
    1,239

    Default

    Did you try the Dominator ECU in the HP car?

  7. #7

    Default

    Not yet, it's a job to swap the ECUs because of how I have them mounted in each car. But I may have no choice but to go through with the swap to see what happens.
    '93 Mustang LX Sedan, Holley Dominator EFI, Twin 66 mm, 347, TH 400, 3.27s - 8.54 @ 162 through the tailpipes on DRs
    '91 Mustang LX Sedan, Holley HP EFI, 410 with Novi 2000, 5 speed, 3.73s - tire destroyer!
    Coming this Fall, 2019 Mustang GT, A10 Auto, 3.0L Whipple - 9 second cruiser?

  8. #8
    Join Date
    Nov 2014
    Location
    Ont. Canada
    Posts
    1,239

    Default

    Ya, if the problem switches cars, you know it's the ECU.

  9. #9

    Default

    My plan is to go through my Dominator car harness with a fine-tooth comb this weekend, then I'll put the Dominator ECU in my wife's supercharged car and see if exhibits the intermittent "no start" phenomenon. I'll update in the near future...hopefully with a resolution.
    '93 Mustang LX Sedan, Holley Dominator EFI, Twin 66 mm, 347, TH 400, 3.27s - 8.54 @ 162 through the tailpipes on DRs
    '91 Mustang LX Sedan, Holley HP EFI, 410 with Novi 2000, 5 speed, 3.73s - tire destroyer!
    Coming this Fall, 2019 Mustang GT, A10 Auto, 3.0L Whipple - 9 second cruiser?

  10. #10
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    21,574

    Default

    This must be your Ford 347 twin turbo engine. Which crank & cam sensors are installed? What does your ignition system consist of?
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: Dominator MPFI & DIS, A/C, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/X-pipe/shorty headers, 100HP progressive dry direct-port NOS, 160A 3G alternator, Optima Red battery, LenTech Strip Terminator wide-ratio AOD/2700 RPM converter, 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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