I picked up a 97 T/A. I have the invoice for new plugs and new opti installed about 300 miles ago at the dealer. Car has rather new wires, and cylinder #8 doesnt fire. The plugs are pretty new, and the opti is new also. I checked it out.

I tried a few simple things out first. I tried swapping the plug from #1 and #8. No change. I put a brand new wire on #8 (not fun), no change. Confirmed it's not firing by pulling the plug wire off while running and had no change.

I'm getting a bit frustrated, the only thing I can think of is the cap and rotor, which is also new.

Any idea's? I'm stumped.

 

Did you consider the possibility it is the fuel injector on #8? Swap two injectors and see if the problem follows the injector. Then it might be a burned valve, incorrectly adjusted valve, etc.

 

I had a plug wire (#6 I think) rub through on an accy pulley one time, right after I put on new wires, and caused a miss because it just grounded out on the pulley. Thats something to check.

 

I would try and get a spark tester on that wire, then if that don't work check the injector as stated before.

 

Can use a timing light to check for spark too... put the clamp over the wire, start it up, and see if the light goes like it should.

 

I wanted to post an update in case someone does a search.

Anyways, the car needed lifters so I went through and replaced all 16 lifters, adjusted the valves, and got everything as it was supposed to be and the miss went away. My best guess is that the dealership who replaced a pushrod adjusted the valves too tight.

Adam, that was a very good suggestion, feel dumb for not trying it.

 

I have an LT1 car I did plugs and wires on myself, and a 3rdgen with shorties... I know all about plug wire problems lol.

Good to see you got it fixed though!