Stop what you are doing, forget everything you observed for the moment.

Your First post says the car drives fine, you say you timed it up and last said you took it for a drive.

What makes you think you have a misfire? not what you observed, what happened that made you to look for a misfire. Anyone one here worth a grain of salt knows a 2.8 down 2 cylinders is a real dog and a sob to start and get to idle, It's REALLY obvious something isn't right.

You'll never time it up on 4 cylinders, It won't drive fine on 4....................


Give us some viable info to work with. if it's misfiring on even 1 cylinder, it will never drive fine. If you do in-fact have a misfire on 2 adjacent cylinders, almost always a bad head gasket and a compression check would be the first and easiest thing to do.

[This message has been edited by jelly2m8 (edited 08-21-2022).]

The reason I say it has a misfire is because it sounds like it does and the idle doesn’t change when two of the back plugs are removed, indicating a miss.

It may be that the miss clears up in the upper rom range, I’m not sure

Just a shot in the dark, could the spark plug wires to the 2 cylinders become reversed somehow? Check the firing order? I like the compression check idea, I know it shouldn't have been affected but that applies to a lot of the above.

Jelly, I like your idea, because it does idle and run pretty well, but it definitely sounds like it’s missing.

If I pull a plug wire off and the sound doesn’t change, I believe it has to be consistently misfiring.

I’m not sure how it would idle fairly well then, I’d be happy to post a video if it would be helpful.
Mark, I’m planning on doing a compression test later this morning when I can borrow a gauge, I agree it’s worth testing but doesn’t make sense

That ! Is awesome Willy ! I bought a 78 firebird two years ago. The guy I bought it from told me it had a miss and swore it was the carb. When I got it home (trailered) found two plug wires swapped…..5&7… corrected it and bam…purred like a kitten.

quote Originally posted by willyt: Mark YOU ARE THE MAN. and I am an idiot. Two plug wires were swapped. Thanks to Patrick Mark and everyone else for their help on this issue. It was so simple that would have taken me a very long time to stop and think of. Oh well, it is fixed now

Thanks & your welcome but you're not an idiot. I'd be very suspect of anyone claiming they never missed a simple problem. I certainly have. And you probably know a lot more about the 2.8 than prior.

Mark, you da man!

Funny how it's the simplest solution which is often overlooked. A good lesson for us all.