INTERMITTENT MISFIRE Cavalier 2002 2.2 SFI

[kanatuna97]

Hello everybody maybe someone can helpi have been fighting a ghost for a long time now.
I have no codes,more often than not i have a misfire,when its not misfiring it runs so very smooth with more power.
I will explain what i havent done and or tried easier that way.
I havent changed the cam sensor or fuel pump and have not checked fuel pressure,Ecu original,Timing chain also.

UPDATE almost forgot as of late I need to let it prime itself before starting the car or else it just turns over.
I sespect fuel pump or bypass modul for my car starter or which is removed.

I have been working on vehicles all my life this has got me stummped and well ive tested replaced with new and known good parts.
ANY ideas.thanks for reading.
113000 kms on my familys car

 

[zora]

hard to believe you have a miss without a code being thrown
is the check engine light on?
when is the last time you changed the fuel filter?
do a fuel pressure test and a compression test.
you are sure you dont have a bad coil?

 

[kanatuna97]

As i said,only thing i havent done was the fuel pressure test as for check engine lite it works fine and so does my scan tool.Compression is perfect

 

[kanatuna97]

maybe ecu i really dont know anymore

 

[zora]

when it misfires exactly what is the engine doing, running rough and no check engine light comes on?
do you intend to do a fuel pressure test?

 

[zora]

any chance it only misfires when you fill the car with gasoline from a gas station that others times you do not use?

 

[kanatuna97]

Hello No notice in gas,But something came to mind,a few days ago.For some reoson there has been issue with our gas in Canada varnish build up in the fuel system,Im going to try find a really decent cleaner because now I beleave check valve in fuel pump sticking.
I seen a youtube video on this subject.

 

[kanatuna97]

when it misfires exactly what is the engine doing, running rough and no check engine light comes on?
do you intend to do a fuel pressure test?

Hello runs rough and jumps according to my code reader my rpms jumping around thru out rpms ,I went to get a fuel pressure tester but it didnt have the proper adapter for my engine,I cant afford to take it in or buy tool at this time,I suspect the fuel pump valve is sticking...Thanks for your reply