97 2.3 5spd wierd miss firing issue

[plowinranger]

So latley ive noticed when i rev the engine over 3500rpms (while driving or at a stand still, it doesnt make a difference) the truck begins to miss fire and run very roughly (its as if one cylinder completely dies) If i let off of the gas and give it just a little gas it will smooth out and run fine again like nothing happend. there is a SES code and it was cyl #2 missfire and that was all.

I have done a complete tuneup and did a compression test, and it has not changed at all. The only thing i can think of is maybe a bad fuel injector? If anybody has any suggestions i would appriciate any and all input, Thanks!

 

[wp23n]

So latley ive noticed when i rev the engine over 3500rpms (while driving or at a stand still, it doesnt make a difference) the truck begins to miss fire and run very roughly (its as if one cylinder completely dies) If i let off of the gas and give it just a little gas it will smooth out and run fine again like nothing happend. there is a SES code and it was cyl #2 missfire and that was all.

I have done a complete tuneup and did a compression test, and it has not changed at all. The only thing i can think of is maybe a bad fuel injector? If anybody has any suggestions i would appriciate any and all input, Thanks!

you dont say how many miles are on it so guessing is tough and this can be caused by many things fuel and electrical

first thing
did you change plug wires? if so are you sure the firing order is correct on both sides? also that you changed and gapped all of the new plugs correctly?
how old is the fuel filter?

first steps i would take after that

check fuel pressure, i believe you can rent a fuel pressure tester from auto zone or advance auto, etc ,etc to see if fuel pressure specs out

check the coil packs.. from what i found out they are a common problem that get weak or just let go, you can try changing the front and rear packs around to see if it makes a difference, the intake side coil pack does not kick in until the truck is actually running

 

[plowinranger]

the truck has 167098 miles and yes, i did put new wires on it and gap the plugs correctly. I will do a fuel pressure test on it today, would you happen to know off hand what the pressure is suppost to be?

 

[Mikel89us]

~40 psi with the engine not running. Locate the fuel pump relay and put a jumper wire across the 30 and 87 terminals to give it constant power ( only do this untill you have a reading then shut it off).

 

[PetesPonies]

Use an inductive timing light and go to each plug wire and check the firing. Point it at underneath your hood and watch the light. If you have a misfire, it will be obvious. Having one wire misfiring verses all of them is a big difference in determining the problem.

 

[plowinranger]

ok, so ive done a fuel pressure test and used my timing light to check for spark, it has 41lbs of fuel pressure and all of the cylinders are firing when it is running rough. So that leads me to belive it could be a dirty or bad fuel injector. Does anybody know what the proper resistance is for a stock ford injector?

 

[PetesPonies]

all you need to do is check for continuity. That will tell a lot about the magnetic coil inside. I can't remember if they are 16 or 16K ohms.