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I have a 2007 Kia Spectra. 2.0L 4 cylinder. the car has 180k on it but only 750 miles on the engine I overhauled. Replacing the rings, head gasket all new bearings, gaskets and seals, water pump, timing belt, plugs and wires.
When I go to start the car it misfires and then evens out after 5-10 seconds and runs fine for the duration of the drive. I sometimes need to rev the engine a little for it to run evenly on startup. Sometimes I get a misfire code for cylinder 2 and once for cylinder 3. It never runs rough or throws a code after this initial event. No other codes are present. It happens whether the car is warm or cold. I have attached the freeze frame data from my scanner. This just started at about 650 miles on the overhauled engine.
When running the scan data it looks good to me but I am no expert. Fuel trims are usually between -3 and 3 on the STFT and LTFT. The A/F sensor and downstream sensors look to operate correctly. A/F sensor is around 2 V and the downstream O2 is around 0.75 V.
My compression is 170-180 psig on each cylinder.
Alternator and battery check out ok.
Spark is good on all cylinders.
No sign of vacuum leaks.I am thinking the fuel injectors at this point or maybe the fuel pressure check valve could be the problem?
I plan to clean/test the injectors, clean the IAC Valve and test fuel pressure tonight.
Any thoughts would be appreciated.
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If you suspect the fuel pump / check valve.
Try cycling the key several times to prime the fuel system before actually starting the engine to see if the issue is still occurring.Thanks for the advice. Last night I checked the fuel pressure and it was around 50 psig and stayed after the car was turned off. I removed and cleaned the fuel injectors and the car seemed to do better starting but once it sat overnight it had the same trouble starting this morning. Once again, once it was started it ran just fine without any codes. I also tested the fuel injector delivery with a tester. They all delivered the same amount of fuel.
I believe the fuel system is not the problem. I have spark, compression, fuel, air. Could the crank sensor not be working on startup, then the car starts to use the cam sensor for operation instead? I guess I will check that tonight.
Not sure what else to check.
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