Hi Dave009,
I am a new DIYer but want to share what I have learned from my automotive experience whenever I can. At the very least, I hope that something I write would spark a new but related idea that another forum members can run with, so here goes-
I have been diagnosing a performance issue on my 1997 Saturn SC2, DOHC, 4 cyl, 5 speed manual trans. I have run many tests that have led me to this point. More recently, I ran an engine power balance test using information from Eric’s video, “How to Perform a Power Balance Test” (my ignition is the DIS design with 1 coil pack per 2 plugs/cylinders) to try to isolate my particular issue. I believe I may have a cylinder misfire with no codes, based on info from Eric’s video, “Diagnosing Engine Performance Issues, Part 1.”
If everything on your ignition system checks out fine (i.e. you have spark, good coils and wires), you can use the power balance test to find a fuel injector issue.
Procedure (as per above referenced Power Balance video):
1) Unplug each injector briefly and listen for change in rpms (If no change, you may have found your problem injector).
2) use a stethoscope (or a long handled screw driver placed on top of the injector with your ear on the handle end of the screw driver. NOTE: Make sure you are not wearing clothing that can be pulled into moving engine components while doing this test) to listen for the click of the injector. If you hear no click (= no pulse), you found a bad injector.
Hope this helps.
P.S.-the above represents quick and effective qualitative types of testing.