Misfire and rough running 98 k2500 5.7

[jaxcob]

More news, was not the gasket issue. Plugs looked okay. I pulled 1, 2, and 4. Played around with wires and double checked everything is plugged in and looks correct. Drove horrible and barely made it out of the drive so didn't try to push it. It'd bog down and almost die and then letting it idle it started doing the same. Did data logging with dash commander and misfire on 1,3,4,5,6,7 shown. CMP is at 2.5. long term fuel trim is bank 1 @ 7.8% and bank 2 @ 23.4%. map reading was steady within 1 kPa at idle. Maf was reading .9lb/min and did fluctuate with throttle.

 

[GoToGuy]

Do you have any codes? You didn't use correct intake gaskets, used " o" rings instead. Are you sure you didn't cause your own problems trying to substitute an engineered product?

 

[jaxcob]

Do you have any codes? You didn't use correct intake gaskets, used " o" rings instead. Are you sure you didn't cause your own problems trying to substitute an engineered product?

No codes beyond the coolant temp sender occasional high voltage which I broke last night accidentally. I replaced the gasket for the map sensor first thing today before I pulled the plugs to check. Somebody prior had rtv'ed it in and I was trying to get the truck back on the road while waiting for the correct part. The truck ran beautifully until yesterday evening

 

[GoToGuy]

Some things can be substituted and functioned as designed. Rule of thumb " Equal to or better ". My first thought, it ran great untill the orings degraded from heat or got sucked into the intake/ cylinders. If you induced a condition you could be " chasing your tail ". Good luck.

 

[wirlybird]

More news, was not the gasket issue. Plugs looked okay. I pulled 1, 2, and 4. Played around with wires and double checked everything is plugged in and looks correct. Drove horrible and barely made it out of the drive so didn't try to push it. It'd bog down and almost die and then letting it idle it started doing the same. Did data logging with dash commander and misfire on 1,3,4,5,6,7 shown. CMP is at 2.5. long term fuel trim is bank 1 @ 7.8% and bank 2 @ 23.4%. map reading was steady within 1 kPa at idle. Maf was reading .9lb/min and did fluctuate with throttle.

What you explain sounds just how mine was when the MAF is going bad. Idled but step on the gas to move and it would bog and sputter. Let off and it would idle. Could abrely get it to drive.
Don't know if that is it or not but sure sounds like mine.

 

[jaxcob]

Some things can be substituted and functioned as designed. Rule of thumb " Equal to or better ". My first thought, it ran great untill the orings degraded from heat or got sucked into the intake/ cylinders. If you induced a condition you could be " chasing your tail ". Good luck.

I did count the orings when I pulled the map back out, I was worried one had fallen off. Got all 6. Guess next on list is diving deeper into the maf.

 

[Macs Garage]

Moisture in distributor cap? Don't cheap out on cap and rotor, it will come back to haunt at most inconvenient time. Been there done that.

 

[jaxcob]

What you explain sounds just how mine was when the MAF is going bad. Idled but step on the gas to move and it would bog and sputter. Let off and it would idle. Could abrely get it to drive.
Don't know if that is it or not but sure sounds like min

Moisture in distributor cap? Don't cheap out on cap and rotor, it will come back to haunt at most inconvenient time. Been there done that.

I did check that just now. Was a bit of corrosion on the contacts inside the cap, cleaned them up and still have a misfire at idle on 3&4. Rotor looked fine. Not fully confident on the plug wires. I fought that on a Dakota for way too long once. Hoping new wires/plugs and looking deeper into the maf is the issue.

 

[Supercharged111]

Dude check the fvkc!ng MAF (and forgive me is you already gave it a visual)! I guarantee that's it. If it looks OK unplug it and go for a rip and come back to tell us how awesome the truck runs.

 

[wirlybird]

You can try cleaning the MAF but not likely to help in my experience.
If you do make sure to use MAF cleaner ONLY.