I got a p0316 and p0304 code coming up, I replaced all vacuum hoses and spark plugs, still the same thing. the check engine lights comes on for a few days then it turns off for a couple of weeks then back on.. my car turns on fine but if I make a small stop and turn it on it starts but turns off after a couple of seconds, the only way to override this is by stepping on the accelerator before it turns off and it’s fine again.. any idea what this might be besides the misfire?
First thought would be intake leak. But would have to test and rule it out. Use the possible causes lists below to further your testing.
P0316 Ford – Misfire Detected On Startup First 1000 Revolutions
Possible causes
– Faulty Crankshaft Position (CKP)
– Crankshaft Position (CKP) sensor harness is open or shorted
– Crankshaft Position (CKP) sensor circuit poor electrical connection
– Ignition System
– Fuel Injectors
– Running out of fuel
– Fuel Quality
– Faulty Engine Control Module (ECM)
The Crankshaft Position (CKP) sensor signal is monitored by the Engine Control Module (ECM) for errors. The P0316 code is set when ECM is detects a misfire during the first 1,000 revolution test interval following engine start.
P0304 Ford – Cylinder 4 Misfire Detected
Possible causes
– Faulty spark plug 4
– Clogged or faulty fuel injector 4
– Faulty ignition coil 4
– Fuel injector 4 harness is open or shorted
– Fuel injector 4 circuit poor electrical connection
– Ignition coil 4 harness is open or shorted
– Ignition coil 4 circuit poor electrical connection
– Insufficient cylinder 4 compression
– Incorrect fuel pressure
– Intake air leak
The P0304 code means that the cylinder 4 is misfiring or is randomly misfiring. Start by checking for intake leaks an if no leaks are found the next step is to replace the spark plugs on cylinder 4. If the problem persist more tests needs to be done to diagnose problem, see “Possible Causes”
When a misfire occurs, engine speed will fluctuate. If the engine speed fluctuates enough to cause the Crankshaft Position (CKP) sensor signal to vary, the Engine Control Module (ECM) can determine that a misfire is occurring.
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