Where is the FI temperature sensor on a 328? | FerrariChat
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Where is the FI temperature sensor on a 328?

Discussion in 'Technical Q&A' started by RGigante, Jun 9, 2007.

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  1. RGigante

    RGigante F1 Rookie
    Owner Project Master

    Nov 1, 2006
    2,874
    Portugal
    #1 RGigante, Jun 9, 2007
    Today I've turned my attention to the fuel injection. At the beginning of the year I've replaced the thermo time switch because I had a hard time starting the car when hot, and checked fuel pressures at a certified Bosch shop. All was ok, and the car starts ok when hot, even if it sometimes takes a bit longer than when cold.

    When I came back from a very "animated" drive today, I've noticed that the exhaust smell seemed to indicate a rich mixture. I've always been a bit suspicious about the fact that when started cold, it never gets the rpm past the 1,000, like I guess it should. It just idles at the same speed, cold or warm. So I've decided to disconnect the auxiliary injector at the plenum (engine warm), and voila, the rpm climbs to 1,400 rpm !!

    That shouldn't happen, since I've checked that the thermo time switch is NOT providing a ground path for the injector with the engine hot, but didn't check if I had 12v at the injector ... So I guess one of two things might be happening:

    1- the injector is faulty and is always on, and someone in the past has "tuned" the idle to compensate
    2- I think there is a separate temperature sensor for the FI. If it's faulty, then the electronics "think" the engine is always cold, and keeps the injector on. I'm assuming in this case that the injector is actuated by the electronics and not directly connected to the thermo time switch. And the water temperature sender and gauge work perfectly ... And where is the temp. sensor for the FI, so I can check it?

    What do you guys think? Any ideias ? The car starts and drives great, but I'm sure this is a problem I need to solve.

    Rui
     
  2. eulk328

    eulk328 F1 Rookie

    Feb 18, 2005
    2,800
    Full Name:
    F683
    #2 eulk328, Jun 10, 2007
    If the injector were faulty (always spraying or leaking) then the problem would not have cleared up when you disconnected it. That is assuming you meant to say you disconnected the electrical connector and not the small fuel line.

    It sounds like the injector is fine but continues to get 12 volts for whatever reason. The separate temperature sensor IS the thermo time switch. Keep in mind the cold start injector is just that.... only for starting/cranking (and only if the coolant temp. is low enough). It should never be spraying when the car is running. Also, it should never be spraying during cranking if the coolant temperature is above.... I think, about 15 degrees Celcius. I believe the thermo time switch does DOES directly activate the cold start injector (versus being controlled by the electronics) but I'm not 100% sure on that one.

    I've had the cold start injector electrical connector disconnected on my 328 for about 7 years because it starts more quickly that way. I never bothered to properly troubleshoot the problem but I did verify that the injector and thermo time switch are good. This situation might be critical if our cars were used as daily transport in winter in areas with really cold weather but typically they are not.

    Erich


     

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