hello,
i posted before about working on a 91, 5.7 c-4. what ive done so far is change the fuel pump, fuel filter, o2 sensor, and the CTS sensor. ( owner also changed the MAP sensor and the TPS sensor) the car starts and runs great until it gets warmed up. absoulutly no codes come up any more but the car still cuts off when it gets hot! the only other clue is that right before it cuts off, it will start making a sucking noise that seems to come from the sensor under the throttle body( which also looks new). once this car starts the cutting off thing, it will start several more times but then will not start again for several hours!??
can anyone give any insight to this problem? im almost ready to give this guy his car back for no charge, because i cant fix it! is it possibly the ECM?
HELP!!!
hello,
i posted before about working on a 91, 5.7 c-4. what ive done so far is change the fuel pump, fuel filter, o2 sensor, and the CTS sensor. ( owner also changed the MAP sensor and the TPS sensor) the car starts and runs great until it gets warmed up. absoulutly no codes come up any more but the car still cuts off when it gets hot! the only other clue is that right before it cuts off, it will start making a sucking noise that seems to come from the sensor under the throttle body( which also looks new). once this car starts the cutting off thing, it will start several more times but then will not start again for several hours!??
can anyone give any insight to this problem? im almost ready to give this guy his car back for no charge, because i cant fix it! is it possibly the ECM?
HELP!!!
Sensor under the TB is the IAC, idle air control.
If you havenīt done it, you might want to take off the TB and then the IAC, spray it with WD-40, let sit for 10-15 minutes.
Clean the TB off course while youīre there, and put it together again.
Putting power on it (the IAC motor) will shoot small parts out of it, so put it in a plastic bag before you attempt ot test it.
I just happened to read this info elsewhere on the forum, so itīs not my personal experience. Just passing it on.
If you havenīt done it, you might want to take off the TB and then the IAC, spray it with WD-40, let sit for 10-15 minutes.
Clean the TB off course while youīre there, and put it together again.
Putting power on it (the IAC motor) will shoot small parts out of it, so put it in a plastic bag before you attempt ot test it.
I just happened to read this info elsewhere on the forum, so itīs not my personal experience. Just passing it on.
thanks! i will try that. ive never seen anything run this good and then just shut off!??
hello,
i posted before about working on a 91, 5.7 c-4. what ive done so far is change the fuel pump, fuel filter, o2 sensor, and the CTS sensor. ( owner also changed the MAP sensor and the TPS sensor) the car starts and runs great until it gets warmed up. absoulutly no codes come up any more but the car still cuts off when it gets hot! the only other clue is that right before it cuts off, it will start making a sucking noise that seems to come from the sensor under the throttle body( which also looks new). once this car starts the cutting off thing, it will start several more times but then will not start again for several hours!??
can anyone give any insight to this problem? im almost ready to give this guy his car back for no charge, because i cant fix it! is it possibly the ECM?
HELP!!!
this is a common problem with multec failure. Get an ohm meter and check each injector. They should read 16 ohms. Do this with the engine hot. If you find any under 8ohms keep it unpluged and try to start. Ashorted injector will shut down the ECU on a 91
this is a common problem with multec failure. Get an ohm meter and check each injector. They should read 16 ohms. Do this with the engine hot. If you find any under 8ohms keep it unpluged and try to start. Ashorted injector will shut down the ECU on a 91
ohmed out all the injectors. found 6 of them under 8 ohms, 1 is 2.6 ohms. only one is above 10 ohms, which the manual states is the lowest reading acceptable. guess ive found my problem. it also explains why it runs fine when its cold, because it is still in "open" loop. thanks for the tip, Im gonna replace them tommorrow
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need help with diagnostics
