Any way to see if ECU is good?
12-11-11 | 03:24 PM
#26
Yeah I kinda figured the ecu was bad. But thanks for helping me troubleshoot guys. And I did disconnect the negative. It's just sometimes I rush into things and don't really think it through. The alternator I got was missing the plastic spacer for the ouput wire and without thinkinng I was like oh this nut will work. Bad idea. Didn't think about the fact it would ground to the alternator housing. That's where all my troubles came from.
12-11-11 | 03:27 PM
#27
You could look at pin 3K of the ECU and either depin it (the Brown wire) or just remove the whole plug and then place a wire into its pin space and check the voltage on it w/key to on. If it still has low voltage such as 2 volts or below then that should definitely place the problem on the ECU.
12-11-11 | 04:01 PM
#28
It's a bit of a head scratcher but the ECU appears to think the car is running when the key is just to on. If the ECU is tricked into thinking the engine is running when it actually isn't then the Light Green wires that pulse a ground to the primary injectors would be doing just that which would explain why the primaries are clicking w/just key to on. I would also bet that if the TPS were disconnected and the Boost sensor vacuum hose disconnected and capped, thus producing a load affect, that the secondaries would also click.
while playing with my injector test stand i noted in almost every combination the ECU always followed CAS cranking speed but pulsewidth varied.
no CAS, no pulse.
12-11-11 | 04:49 PM
#29
Rotary Freak
Joined: Jul 2008
Posts: 1,660
Likes: 1
From: FORT WORTH TEXAS
Pull the plugs off the ECU the next time you hear what you say are fuel injectors clicking and fuel pump resistor relay clickiing. Leave the key ON.
If the clicking continures then it ain't the ECU. Only thing running would be the fuel pump.
OR the clicking you hear could be the BAC and not the injectors. Pull the BAC's plug next time you hear the clickiing. IF the click goes away............iit was the BAC clicking and not fuel injectors.
LIke the man said, fuel injectors can only click if the engine is spinning and CAS installed.
1986 FSM............non turbo cars........has you listen for the pulsing sounds of the PD when the fuel pump is running.
If the clicking continures then it ain't the ECU. Only thing running would be the fuel pump.
OR the clicking you hear could be the BAC and not the injectors. Pull the BAC's plug next time you hear the clickiing. IF the click goes away............iit was the BAC clicking and not fuel injectors.
LIke the man said, fuel injectors can only click if the engine is spinning and CAS installed.
1986 FSM............non turbo cars........has you listen for the pulsing sounds of the PD when the fuel pump is running.
12-11-11 | 04:51 PM
#30
well, the ECU cannot cycle the injectors without a pulsed CAS signal. the stock ECU has nothing to emulate a predetermined injector output signal. in other words it is always timed off the CAS, if the CAS isn't spinning then the injectors shouldn't be pulsing.
while playing with my injector test stand i noted in almost every combination the ECU always followed CAS cranking speed but pulsewidth varied.
no CAS, no pulse.
while playing with my injector test stand i noted in almost every combination the ECU always followed CAS cranking speed but pulsewidth varied.
no CAS, no pulse.
12-11-11 | 04:58 PM
#31
well what i mean is i don't think there is any programming in the ROM at all that cycles fuel outside of reading the CAS input and using that as the trigger speed.
my first thought was with Hailers that the sound he was hearing was from the BAC but i don't know if when he removed the UIM if he removed it completely. the BAC is in a different area and should be easy to rule out. the fuel system will make a "woosh" sound from fuel flowing through the rails, far from a clicking sound from the injectors or buzzing from the BAC.
sometimes i hate guessing what people think according to their descriptions. i somehow doubt the injectors are pulsing at all. if they are somehow and it is ECU related i would almost guarantee something is making a very poor contact causes voltage or ground to cycle on and off rapidly, which will eventually burn up completely and hopefully show the true root of the issue.
to rule out that the injectors are somehow pulsing. remove the rails, strap the injectors to them and turn the key on. if they aren't dousing the bay with fuel, rule it out and move on.
my first thought was with Hailers that the sound he was hearing was from the BAC but i don't know if when he removed the UIM if he removed it completely. the BAC is in a different area and should be easy to rule out. the fuel system will make a "woosh" sound from fuel flowing through the rails, far from a clicking sound from the injectors or buzzing from the BAC.
sometimes i hate guessing what people think according to their descriptions. i somehow doubt the injectors are pulsing at all. if they are somehow and it is ECU related i would almost guarantee something is making a very poor contact causes voltage or ground to cycle on and off rapidly, which will eventually burn up completely and hopefully show the true root of the issue.
to rule out that the injectors are somehow pulsing. remove the rails, strap the injectors to them and turn the key on. if they aren't dousing the bay with fuel, rule it out and move on.
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