I have a '98 with the 3800 Series II engine. I got it dirt cheap, but of course there's a reason for that.

I had some diagnostics run on it, and it's showing a misfire on cylinder #2 and low compression (65psi) on cylinder #4.

My first order of business is to pull the head on the rear cylinder bank and see what's going on with #4. Hopefully it's a burnt valve or something else that can be cured with a head swap. If it's something deeper like a damaged piston or ring, I may have to just offload the car because I don't have the means to deal with something like that right now.

Assuming I cure what ails #4, it's on to that misfire on #2. What are some possible causes of that? Coil pack? Mass air flow sensor? Spark plug or wire? The coil packs on my car are numbered, which I'm told is an indicator that they're OEM and should be replaced.

If I do fix the various problems, will the codes related to them automatically clear the next time the car is run? Or do I have to clear them by some external means?

The car is also displaying some codes related to the ABS, and the Air Bag and Security lights are also on, but those are future discussions.

 

A bad coil pack, spark plug, wire, MAF can all cause misfires. So can a failing fuel pump or injector. But no, the codes will not clear unless you unplug the battery for half an hour or so, or start the car 50? times with the faults not being present - then the light will go off.

Good luck with the ABS, mine hasn't worked in years. The airbag could just be unplugged, look under the dash (under the kick panel under the steering wheel, it's the yellow wire)

The security light is likely an issue with the VATS, you can either use resistors that match your key, or check this site: vats.likeabigdog.com

Good luck...