Need a Misfire Cure

[The Banks]

My car has been missing for a little over a week now and I'm completely stumped on what could be the problem. I've replaced the fuel filter, checked primary and secondary resistance on coils, checked O2 sensors and just about every other sensor imaginable, checked my cat for rattles, checked and regapped plugs, and put on a new wireset. Funny thing is that after I replaced the wires the SES light went off and I'm not getting any DTC codes when I scan it, but it still misses exactly the same.
2000 3.8 A4 ~54,000 miles.

[Jaysan]

Re: Need a Misfire Cure

does it sputter when trying to accelerate ? Might be ignitions coils or your ignition module the thing under the ignition coils

[flamingchicken]

Re: Need a Misfire Cure

have you recently done any work around the plugs...cracked porcilan? maybe

[ne0hisda0ne]

Re: Need a Misfire Cure

My car has been missing for a little over a week now and I'm completely stumped on what could be the problem. I've replaced the fuel filter, checked primary and secondary resistance on coils, checked O2 sensors and just about every other sensor imaginable, checked my cat for rattles, checked and regapped plugs, and put on a new wireset. Funny thing is that after I replaced the wires the SES light went off and I'm not getting any DTC codes when I scan it, but it still misses exactly the same.
2000 3.8 A4 ~54,000 miles.

Been having similiar issues with mine...sure if you had cracked plugs you would of noticed it when you were regapping them. Did you do the spark plug test to see if they all arcd' blue? Yellow is a weak wire, or plug, but since you replaced the wireset that only leaves the plug test. I've replaced all my coils, wires and plugs and mine is still misfiring, I also have no code, but my light isn't coming on at all. I am going to pick up a compression tester and fuel pressure gauge from autozone or advanced to test it. I suggest you do the same if you really want to get to the bottom of this.

Fuel pressure on your 3800 motor.....

~48-55 psi (ignition ON)
~3-10 psi loss at idle

For a compression test:

~Around 140 to 155psi on all cylinders.
~With no more than %10 (about 20psi) difference between all cylinders.
~Do this with ALL spark plugs removed, the throttle wide open, and turn the motor over about 4 to 5 times.

[ne0hisda0ne]

Re: Need a Misfire Cure

does it sputter when trying to accelerate ? Might be ignitions coils or your ignition module the thing under the ignition coils

and if the pressure checks out jaysan may have it here, I've noticed when I checked my resistance that some of them would be 6.5k and others would be 8.5k..didn't matter if I tested in the car or on the bench. So I don't know if testing resistance is really a good test to do. My next step anyways if my pressure checks out would be replacing my module since I already replaced all my coils. Good luck!

- Peace!

[The Banks]

Re: Need a Misfire Cure

Well I tested my whole ignition the old fashioned way (took the wire and plug out and checked the arc) and discovered that my coil for cylinders 2 and 5 was bad) I swapped in a good coil from the other 95 3.8 with a 2 year old GM installed powertrain and walla. Even though I checked all my coils with a voltmeter and they had good resistance they turned out being the bane of the majority of my spring break.

[ne0hisda0ne]

Re: Need a Misfire Cure

:banana: