1997 F355 wont start, no injector pulse.... | FerrariChat
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1997 F355 wont start, no injector pulse....

Discussion in 'Technical Q&A' started by GS70350, Jan 10, 2006.

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  1. GS70350

    GS70350 Rookie

    Jan 10, 2006
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    Huntsville, Alabama
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    Jacob Morse
    #1 GS70350, Jan 10, 2006
    Hey guys, title says it all, anyone had this issue? Im technically savvy, so any help you can throw my way would be of great help, im new to this forum but it looks like some knowledge is floating around here. . .


    Checked the cam sensor and crank sensor and they are both clickin it off. Using a noid lite, i tested the injectors to see if they were getting pulse and they are NOT.

    However every now and then it will sputter as if it intermittently gets fuel, then loses a electrical connection. Sounds like some wiring or connectivity issues in the electrical system, but i dont know where to look. Ive got the fuse box under the dash open and the Motronic behind the seat out. What should i check first?

    Any information on which relays to check, fuses, or particular problem areas that may cause this please let me know, im sick of it sitting here i want to drive it!!!!!
     
  2. ernie

    ernie Two Time F1 World Champ
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    #2 ernie, Jan 10, 2006
    Just some ideas here.

    Have you check the fuel pressure yet? It could be a bad fuel pressure regulator or a bad fuel pump. Also have you pulled the ECU codes. They could get you pointed in the right direction quicker.

    One more thing did you check the condition of the wires under the rubber boots for the connectors? The Ferrari electrics are notorious for busted wires in places you don't think they will break.
     
  3. tbakowsky

    tbakowsky Two Time F1 World Champ
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    #3 tbakowsky, Jan 10, 2006
    If your engine has been removed at all in the past..check the rubber gromet which the main wiring harness passes through the firewall to the ECU. Somtimes these do not get put back in place. When this happends the wiring will chafe on the sharp metal of the harness opening causing all kinds of difficulty. I have seen this more then once..almost the same symptoms as you are discribing.
     
  4. GS70350

    GS70350 Rookie

    Jan 10, 2006
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    Jacob Morse
    #4 GS70350, Jan 10, 2006
    Thanks for the input. on the fuel pressure....

    It doesnt have injector pulse, but i havent checked the pressure. I can hear the pump prime though so im pretty sure its got pressure, just isnt injecting it into the cylinders due to some other reason. That rules out FPR and fuel pump.

    On the codes, ive checked the codes and it shows nothing wrong, zip, nada, perfect condition.

    This leads me to believe that once again its a wiring issue.

    ""The Ferrari electrics are notorious for busted wires in places you don't think they will break.""

    Which connectors should I check in particular, the ECU connections or somewhere else? Just wondering if certain electrical connections are faulty more frequently than others.

    Thanks for the input about the firewall wiring harness, the car was hit in the front hard and repaired about 2 years ago so this sounds like a likely possibility, ill definately look.
     
  5. ferrarioldman

    ferrarioldman Formula 3
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    Tom Jones
    #5 ferrarioldman, Jan 10, 2006
    Silly suggestion but I assume that you hit the remote to deactivate the immobilizer.....
     
  6. GS70350

    GS70350 Rookie

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    Jacob Morse
    #6 GS70350, Jan 10, 2006
    ya hit the remote to activate demobilizer every time of course, could it be that if the battery is low in the demobilizer it could cause an issue like this?

    Occasionally, like day to day, it will hit it over a lick or two before deciding not to start.
     
  7. LSU348

    LSU348 Formula 3

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    #7 LSU348, Jan 10, 2006
    Did you pull your RPM sensor and check that you were not getting a short across it? I do not remember what the resistance should show but I want to say 400 ohms. I am not sure if you would get any signal with a partial short but it might give you a nerd meter light flash but not give a full pulse to the system. This, of course, assumes your can has an RPM sensor...I only have experience with my 85 QV.
     
  8. ferrarioldman

    ferrarioldman Formula 3
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    #8 ferrarioldman, Jan 10, 2006
    There has been an issue with the alarm/immobilizer. I would have to dig out the service bulletin to recall which cars were affected but I seem to remember it being cars of that era.
     
  9. GS70350

    GS70350 Rookie

    Jan 10, 2006
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    Jacob Morse
    #9 GS70350, Jan 10, 2006
    Alright thanks for the info. Ill check the RPM sensor.

    Any info anyone has about the demobilizer let me know, ill see about putting a battery in it though.

    Thanks again guys
     
  10. Motob

    Motob Formula 3
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    #10 Motob, Jan 10, 2006
    Last edited by a moderator: Sep 7, 2017
    Do you have spark? If you have spark, then the Motronic control unit is getting the proper signals from the speed and reference sensors.

    If the injectors aren't firing (a noid light works great, I also use a stethescope and listen to the injectors click), they may not have power from the injection relay. The relay is under the passenger footrest.

    The relay supplies 12V to one of the pins of the injector connector and the Motronic control unit ground the other pin to fire the injector. Check with a test light connected to a good ground to see if you have power at the injector connector, if not then there may be a problem with the injection relay. See diagram, assuming you have a USA version, non-Challange car with Bosch 5.2 injection. Also check fuse #30.

    Another possible cause of having spark but no injector pulse is a bad ground at the fuel injection harness to engine ground. The ground wires that go into the Motronic control unit are split up, so the spark portion of the brain may have a good ground, but the injection portion may not.

    The other cause besides a faulty imobilizer is a possibly defective Motronic control unit.

    Good luck,
    Brian
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  11. GS70350

    GS70350 Rookie

    Jan 10, 2006
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    #11 GS70350, Jan 11, 2006
    Alright guys new information. Car has no spark either.

    I checked all the relays and they all work fine. There is fuel pressure and the pumps work well. There is 12V+ power to the injector harness, and 12V+ power to the ignition system as well, but the Motronic is not sending the ground signals.

    I have a '95 wiring harness for the engine control system, is it the same as a 97 or did it change with OBDII?

    I have a autodiagnosis breakout box hooked up to the Motronic ECM and im trying to figure out which grounds to check. The way i figure if the grounds dont check out, then ill trace wires and if they do check out, then the ECM is bad?

    I will scan the wiring diagram from Ferrari and post it here in about 3 hours for you guys to analyze, its somewhat of a pain to trace everything.

    Thanks for the help.
     
  12. ferrarioldman

    ferrarioldman Formula 3
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    #12 ferrarioldman, Jan 11, 2006
    I have a '95 wiring harness for the engine control system, is it the same as a 97 or did it change with OBDII?

    Does this mean that you have a '95 wiring diagram that you are trying to use for a '97 model?? If so, it isn't the same as a '97 diagram.
     
  13. GS70350

    GS70350 Rookie

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    #13 GS70350, Jan 11, 2006
    Yea i figured it out from searching these forums im learning more every day.

    SO i need a wiring diagram for a motronic 5.2 system not the 2.7 system from 95. Thats just what i found. Anyone got any information? Thanks
     
  14. ernie

    ernie Two Time F1 World Champ
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    #14 ernie, Jan 12, 2006
    This is just a shot in the dark, but try unplugging the cat ecu's. Disconnect the battery for 30 seconds, then reconnect it. Try starting it up.

    The reason I'm suggesting it is because the cat ecu will send a signal to the motronic to shut the engine off if it thinks the cat is over heating. Also people have been know to remove the "slow down" bulbs in the dash. So it could be something as simple as that. At worst you'll only loose 30 seconds of your time. Again just guessing here.
     
  15. rexrcr

    rexrcr Formula 3
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    #15 rexrcr, Jan 16, 2006
    You have a breakout box... excellent. You need the pin test procedure that's in Ferrari's breakout box info binder. I don't have access any more to the information.

    Anyone else?


    BTW, great post Motob ;)
     

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