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.

 

The ICM could possibly be fouled out. Get a compression test done as well.

 

Intermittent Fuel Injector?

 

is it a steady misfire ? or does it happen only at certain times ?

 

I'm leaning towards the idea that its an electrical problem because I was using HP tuners yesterday to scan it and try to use the misfire counter to see how many times I'm missing and from which cylinder. Because I was getting a P0300 (random/multiple misfire) code but now I'm not getting anything. I'm not so sure that it could be a comp problem because it tends to misfire intermittently.

 

Check your relays under the hood one might be in backwards my friend had this problem

 

Well I tested my whole ignition the old fashioned way today (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. I think I'm going to go with an ebay seller called Ecaronline for my new coils. They have OEM AC Delco coils for $17.99 each when they usually cost +$50 each in parts stores. Someone on the v6camaro forum vouched for them in a tune up sticky so they must be reputable. And I was just about to spring for MSD coils for $47 each at Autozone.

 

If you can afford them, get the jegs coils. The msd's are crap, and don't last long (though a FEW people do have luck with them, I stress few). Cheapo reproductions generally aren't very good. The jegs coils are a popular choice because they last long, and actually put out a little bit more juice than the stockers, which is impressive.

 

AC delco used to make a nice spark tester part# ST-25. They had a HEI version that force the secondary ignition to fire at 30,000 Volt. Most coils that are starting to fail will pass a resistance test but would not pass the ST-25 test. Since the ST-25 was designed for an HEI it is pretty low power for your DIS. The nice part is you can just run 2 of them one on each side of the coil and stress the coil to 60,000 volts. If a coil will fire 60K it will fire a plug under load.

I can't seem to find them anymore, I think maybe they where a safty risk since they where exposted spark one bad back fire on an older car and you would have a problem.

 

when i changed my spark plugs from the stock ac delco to bosch
my car began to misfire.
one of my teachers at school said that the new spark plugs might be the problem.