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I have a 99 cavalier 2.2
I have codes
P0118 Engine Coolant Temperature Circuit High Input
P0141 02 Sensor Heater Circuit Malfunction (Bank 1 Sensor 2)
P0300 Random/Multiple Cylinder Misfire Detected
P0442 Evaporative Emission Control System Leak Detected (small leak)
P0452 Evaporative Emission Control System Pressure Sensor Low InputThe one I’m most worried about and have been working on figuring out is the P0300. I have replaced all plugs (.050 gap) and wires due to plugs were way out of spec and just old. (.015-.025) to big. It ran well for a while. The check engine light actually went out once it completed a drive cycle. Then the next day i went to start it and bam misfire again then bam check engine light on again. I tested the coils and both primary and secondary coils were within spec. I also tested for power and ground on the ICU (ignition control unit) both good. I also tried testing the input signal to the ICU. My meter was not up to the task and could not read fast enough. I need a scope or a better meter.
I wouldn’t think the 02 sensor would cause this nor the evap small leak I could be wrong and I hope someone with experience could help me with this problem. If i had a better scanner i could figure it out in no time but I don’t have a few grand to spend. Who does. :confused:
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The p0141 check the fuses for the o2 sensor.check the heater circuit itself
with an ohm meter.P03oo could be from the o2 having a problem.due a power balance
test.p0118 check the wiring and connector.Is the car running hot?check the coolant
level.it should be clean and full.I also posted a link for a wiring diagram.http://www.bbbind.com/tech_database.html wiring diagram
car is not running hot at all. The coolant level is fine. Ill try to test the o2 sensor with my meter. Ill post results
Based on your description I wouldn’t think it was an O2 sensor either. Now we need to find out if the misfire is caused by an ignition issue or a fuel delivery issue. I don’t think it’s mechanical, if it was I would think it would act up all the time. The coolant temp sensor might be a good place to look however since your problem seems to be temperature related. I might track down that issue first and recheck for the misfire. I’d leave the evap stuff till last as that’s more of a passive system anyway and would not normally effect engine performance.
[quote=”EricTheCarGuy” post=32402]Based on your description I wouldn’t think it was an O2 sensor either. Now we need to find out if the misfire is caused by an ignition issue or a fuel delivery issue. I don’t think it’s mechanical, if it was I would think it would act up all the time. The coolant temp sensor might be a good place to look however since your problem seems to be temperature related. I might track down that issue first and recheck for the misfire. I’d leave the evap stuff till last as that’s more of a passive system anyway and would not normally effect engine performance.[/quote]ok I will also try to track down some specs on the coolant sensor and test it with my Meter. I believe if i am remembering right the voltage should be higher when cold and go down when the engine warms? I will post results.
Ok, 3 of those codes if not all, are probably caused by faulty electrical. Check everything. Grounds, connections, fuses, relays, etc. Anything electrical. Also check your sensors for proper operation. If bad, change them. Your ECT sensor and o2’s would be a good place to start.
[quote=”EndSupremacy” post=32457]Ok, 3 of those codes if not all, are probably caused by faulty electrical. Check everything. Grounds, connections, fuses, relays, etc. Anything electrical. Also check your sensors for proper operation. If bad, change them. Your ECT sensor and o2’s would be a good place to start.[/quote] Yea plan on doing in the morning. I will post results also.
I forgot to mention that you also might have some shorts. Check for short to grounds and short to power.
First I’d recommend getting a wiring diagram for the fan circuit and find out how it’s suppose to work, they may run a separate switch for the fans and it doesn’t run off of the temp sensor. Study the circuit before you start so you don’t waste your time looking for things that have nothing to do with the problem you’re having.
Well i got to test the ECT sensor today and that works. I noticed today the temp gauge on the dash was pegged on Cold. Whats up with that? I also noticed it has a hard start/ long crank time before it would start after i would drive it. Almost like it was flooded. Also another is that it will only hesitate when just cruising down the road under light throttle, don’t notice under acceleration. I still have to check some other things out but ran out of time today.
[quote=”EricTheCarGuy” post=32512]First I’d recommend getting a wiring diagram for the fan circuit and find out how it’s suppose to work, they may run a separate switch for the fans and it doesn’t run off of the temp sensor. Study the circuit before you start so you don’t waste your time looking for things that have nothing to do with the problem you’re having.[/quote]Looks like its seperate.
[quote=”stormer1092″ post=32567]Well i got to test the ECT sensor today and that works. I noticed today the temp gauge on the dash was pegged on Cold. Whats up with that? I also noticed it has a hard start/ long crank time before it would start after i would drive it. Almost like it was flooded. Also another is that it will only hesitate when just cruising down the road under light throttle, don’t notice under acceleration. I still have to check some other things out but ran out of time today.[/quote]
It sounds like it might be some connection issues with the BCM or ground connections.
All that diagram tells me is that the PCM controls the cooling fan relay. Since you have an issue with the temperature reading on the dash this might mean 1 of 2 things. The first is that there is an issue between the sensor and the inside of the car, if the coolant temp sensor sends it’s signal to both the PCM AND the temp gauge it could mean that the PCM is not being told that the engine is hot so it’s not turning on the fan. It’s also possible that there are separate sensors for the dash and the PCM in which case you would need to make sure you tested the correct sensor.
[quote=”EricTheCarGuy” post=32639]All that diagram tells me is that the PCM controls the cooling fan relay. Since you have an issue with the temperature reading on the dash this might mean 1 of 2 things. The first is that there is an issue between the sensor and the inside of the car, if the coolant temp sensor sends it’s signal to both the PCM AND the temp gauge it could mean that the PCM is not being told that the engine is hot so it’s not turning on the fan. It’s also possible that there are separate sensors for the dash and the PCM in which case you would need to make sure you tested the correct sensor.[/quote] Well i just was messing around and I found that when i wiggle the wire loom around the ICM the engine will die down. (top of picture) I have a starting point at least. I also read the fan will kick on 100% of the time if the ECT sensor is bad i could be wrong tho. I have to dig around and see what i can get. I also tested the 2 wire ECT sensor on the top of the engine. I made sure I was testing the right one. I made that mistake before.
Well problem fixed! The signal wire going to the ICM was shorting out! Thanks for all the help guys!
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