I've been having this problem since the engine was rebuilt about a year ago. I get a random misfire code. When the engine light is on, it will stall in cold weather and the engine rocks back and forth a lot. Then the code goes away on its own and it runs great. Until the next misfire. I have changed everything in the ignition system, the first O2 Sensor and the EGR valve. The only thing I can think of now is the injectors or that second O2 sensor. Any experts run across this before or might have another suggestion? Thanks
'97 Sunfire 2.4L
- Thread starter msfaulk
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These are the possible causes of P0300, sounds like you have tried some of them already.
•Faulty spark plugs or wires
•Faulty coil (pack)
•Faulty oxygen sensor(s)
•Faulty fuel injector(s)
•Burned exhaust valve
•Faulty catalytic converter(s)
•Stuck/blocked EGR valve / passages
•Faulty camshaft position sensor
•Defective computer
•Faulty spark plugs or wires
•Faulty coil (pack)
•Faulty oxygen sensor(s)
•Faulty fuel injector(s)
•Burned exhaust valve
•Faulty catalytic converter(s)
•Stuck/blocked EGR valve / passages
•Faulty camshaft position sensor
•Defective computer
______________________________
Plugs and wires are new
Coil Packs are new
Exhaust valves are good
Catalytic converter is new
EGR valve is new
And I the computer was the first thing I changed, ( I returned the new computer when it didn't fix the problem).
So looks like I need to see about the second o2 sensor, the fuel injectors, and the camshaft position sensor. I just hate throwing parts at something hopeing it fixes it. Thanks
There's also a crankshaft position sensor. It lives above the oil filter.
Have you checked all system grounds?
Since it runs well once warm, maybe the temperature sensor for the PCM has a problem?
As well, the MAP, MAF, IAT, TPS, sensors all need to be checked for proper operation.
If you do not have a real time scanner that can read the outputs from all sensors, you're going to spend a lot of time and money replacing parts that do not need replacing. Throwing parts at a car in an effort to find a problem gets expensive real quick.
Check out eBay. A lot of oldtimers, not unlike myself, are retiring, and a sometimes a well equipped Snap on MT2500, some with graphing, can be bought for a couple hundred bucks. IIRC, a MT2500 with a 7.0 software version will cover cars up to 05? Look for one that has programmable cartridges because they seem to have the latest software more times than not. Keep in mind that the MT cost about 2500 or more new, it is not a piece of junk.
A good scanner is an investment that will last for years, and you can charge all of your buddies 25 bucks a pop for turning off their CEL as well. Just my $.02. Best of luck.
Have you checked all system grounds?
Since it runs well once warm, maybe the temperature sensor for the PCM has a problem?
As well, the MAP, MAF, IAT, TPS, sensors all need to be checked for proper operation.
If you do not have a real time scanner that can read the outputs from all sensors, you're going to spend a lot of time and money replacing parts that do not need replacing. Throwing parts at a car in an effort to find a problem gets expensive real quick.
Check out eBay. A lot of oldtimers, not unlike myself, are retiring, and a sometimes a well equipped Snap on MT2500, some with graphing, can be bought for a couple hundred bucks. IIRC, a MT2500 with a 7.0 software version will cover cars up to 05? Look for one that has programmable cartridges because they seem to have the latest software more times than not. Keep in mind that the MT cost about 2500 or more new, it is not a piece of junk.
A good scanner is an investment that will last for years, and you can charge all of your buddies 25 bucks a pop for turning off their CEL as well. Just my $.02. Best of luck.