Misfire
 

Hey all,

04 Chevy Blazer with 93k miles on it. Got it about two years ago and have had this problem intermittent ever since. Under load (mainly going up a hill) between 45 and 60 mph it will misfire, and on the bad days it will misfire bad enough to make the SES light flash (multiple misfire). Also, when its warmed up and after a few hours of it running it has a hard time starting. It will turn over fine just not start without quite a few turn overs.

Over the duration of owning it, I have done a tune up (plugs, wires, cap, rotor) which did not solve the problem. Recently I did the fuel pump and filter (it went out) and that didn't fix it either. I also put on a new fuel pressure regulator thinking it wasn't maintaining enough pressure but that did not help either.

Also put on a new alternator and experimented with a different coil pack from another blazer I have, also no difference.

Getting kind of sick of the issue as it does it more frequently in the winter months. Not sure what else I can do, looking for some wisdom. Really don't want to take it to the shop but if it pisses me off enough I just might.

Thanks!

Maybe the ignition module. I had two fail on me with various symptoms. One had misses as yours. The other one refused to start when hot but would start just fine at cold engine and also run fine until I shut it down and tried to restart when hot.

Would that be the part that is attached to the same bracket as the coil pack? I replaced that as well. Are you referring to something in the PCM or key ignition?

Electrical misfires inside the distributor cap are a common problem. Check cam sensor retard with a capable scanner ($30 + Android phone) - should be 0° ± 2°

Don't have any codes, I'll have to try the TPS, only thing I haven't tried yet. How could I reset the cam sensor retard? The cap and rotor are still pretty new.

look inside your throttle body, under the plenum, it should not be shiny gold color. Should be carbon black. Also its a long shot but i had this problem also. After doing all kinds of stuff like you, it was a loose plug

The intake manifold and throttle body are still clean, not carbon black, but that's because I cleaned it up when I replaced the lower gaskets a few months ago. Plugs and wires are good, I just put in double platinum plugs.

So I've changed out almost every sensor on the manifold. TPS, MAF, MAP, Air temp. Done a full tune up, so I'm not sure what it is. No codes either. Any other ideas?