NEED HELP Can't quite figure this one out.

Kansasborn

Original poster
Member
Sep 25, 2019
1
Paola, Ks
Ok, so I fairly sure this issue has been discussed before but here we go. So a little history. I bought my 02 Tb LS base model in 2014 with I believe 181, ??? miles. Had 1 big repair within first 2 years (radiator) This has been a very solid, reliable SUV up until this point.Now 5 years later I've had the worst time trying to find the problem to the misfire. It started @ cyl 4, then random/multiple, then cyl 5, then back to random. I checked and replaced all coils, plugs, a few coil connectors, replaced the fuel pressure regulator, purge valve & vent valve solenoid, fuel filter, fuel pump and sending unit, ignition switch. So last night I wanted to check to see if I had any fuel pressure by releasing some at Schrader valve. None at all. Where do I go from here. I'm about ready to throw my hands up. Any thoughts?
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
Yep. Been there:


Might not be exactly the same problem as yours but has pretty much the same troubleshooting steps for all types of misfires. I have not yet swapped the crank sensor or replaced the O2 sensor as I usually don't let it idle too long
 

Maverick6587

Member
Dec 16, 2018
730
Sterling Heights, Michigan
Good point @KEEBZ489. Did you use AcDelco coils and spark plugs?

You mentioned testing fuel pressure. Is it not starting now?
I had a similar issue with a slight miss. I replaced everything that you have so far and then went for the MAF sensor and MAP sensor and that fixed the issue.
 

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