classic kev
Well-Known Member
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You say you replaced coolant temperature sensor - which one? There is the little one for the gauge, then there is the coolant thermistor which is connected to the ECU, then there is another a coolant temperature switch for the AC fans. The coolant thermistor is the one I think you might be thinking of, these are expensive but can be checked with a meter. Also, if suspect, pull the plug and bridge it with a paperclip, brings the resistance right down so ECU thinks "hot" so mixture shouldn't be rich as in "cold".
Check engine light, easy to resolve, unplug ECU or disconnect battery, this will erase fault codes but not sure if yours will have the fault code display, I believe it should being a US car but not sure if the code display retains any stored faults. If the MAF isn't working properly, the engine will run but it will be rich and check light should come on. the MAF sensor ground, CO trim, battery feed and air flow can all be checked with a meter. If temp thermistor is wrong then possibly ecu is adding cold enrichment. This can be checked with a meter. Throttle pot adjustment is not likely to be your problem but again, simple testing with a multi meter is easy.
Fuel temperature thermistor, not known that to be a problem but this can be checked with a meter.
Don't know if you have looked through the V8 section of the forum, lots of info and answers in there. The 4.2 is no different to the 3.9's in as much as it is the same ignition system and fuel injection ECU etc.I'm fairly sure I have posted how to check most of the EFI using a meter in there so maybe have a gander.
HTH.
Check engine light, easy to resolve, unplug ECU or disconnect battery, this will erase fault codes but not sure if yours will have the fault code display, I believe it should being a US car but not sure if the code display retains any stored faults. If the MAF isn't working properly, the engine will run but it will be rich and check light should come on. the MAF sensor ground, CO trim, battery feed and air flow can all be checked with a meter. If temp thermistor is wrong then possibly ecu is adding cold enrichment. This can be checked with a meter. Throttle pot adjustment is not likely to be your problem but again, simple testing with a multi meter is easy.
Fuel temperature thermistor, not known that to be a problem but this can be checked with a meter.
Don't know if you have looked through the V8 section of the forum, lots of info and answers in there. The 4.2 is no different to the 3.9's in as much as it is the same ignition system and fuel injection ECU etc.I'm fairly sure I have posted how to check most of the EFI using a meter in there so maybe have a gander.
HTH.