I'll add 2.5 cents.
It is not unreasonable, given OBD-II said he had a number of misfires in #3, to change plugs and maybe wires.
I would have looked at the plug and measured resistance in the wire first.
Since they have been replaced and it is still missing, I would at least check compression on #3 to eliminate a mechanical problem, or verify one.
Could be a gasket/injector problem as Service Writer mentioned. A cooling system pressure/noid test would verify this.
Normally on a cylinder misfire, I would check spark on that cylinder with a plug tester and use a noid light on the injector, then go to compression test, then a cooling system pressure test.
The main reason I would follow this procedure is that it makes no sense to throw parts at a problem, you may get lucky and hit it the first time, then again, it may be the last part you buy.
KC eluded to this in the shotgun analogy, I agree.
If you are new to working on a car, the best investment you can make is a factory service manual, or at least a Haynes manual.
As an example I am trying to find out why the cooling fans on a 1991 Corolla are not working, the factory manual has some 42 seperate steps to try and isolate the problem. I'll start with the first step this weekend (fuses) and go from there.
I must say that is far easier (obviously) to diagnose a problem like this when you have the car in front of you than over an internet forum.
I think our mission is to give information based on our experience. It also is our responsibility to tell a forum member to "punt", and take the car to a professional. I have done as much in the past, myself.
Friday, March 23rd, 2007 AT 8:21 AM