So I just got done removing all the C.O.P's and spark plugs. I cleaning all the spark plugs with a wire brush and re gaped them all the plugs looked pretty good except the #5 plug looked horrible, it was really gunked up so I cleaned it up real nice. I sprayed all the C.O.P's and connectors with electrical cleaner and it still didn't help the miss fire if anything it made it run worse.

I guess I'm just going to buy a compression tester kit and check that next.

 

The good news its #5 and easy to access. If that plug was "gunked" up it isn't firing properly. It could be the plug, cop, or compression. Maybe just replace both on that cylinder if compression comes back good.
Also, make sure you use anti seize when re-installing any plugs.

 

The #5 cylinder on this 6.8 is on the passenger head all the way in the back its not very accessible as gunked up as the plug was this engine probably needs rings but wont know for sure till i run compression test

 

OH ya, it's a V-10, not a V-8. Thx.

 

Or maybe the number 5 plug has not been changed before, due to its location.
I would replace that plug, and at the least , the boot and spring.


Does your pending code state what is pending?
An 0171code is a fuel code.
That should lead to a bad injector.

 

Okay so I finally got around to starting a compression test on this thing

I started with the #5 cylinder because I thought that was the bad one but it measured 130 PSI witch is fine I'm sure

However the #4 Cylinder only read 90 PSI

Before I could test the rest of the cylinders the truck wouldn't turn over any more when I turn the key the dash lights come on and it just clicks like the battery is dead or low but the battery tested 13 Volts on the DVOM not to mention it was cranking over one minute and then not cranking the next

I tried moving the shift lever around thinking maybe it was stuck in between gears or something because when I purchased the truck It wouldn't go into park I had to start it in neutral

Any ideas in why it won't turn over now anything under the dash that can go bad causing this no turn over condition

I guess I bought a lemon *** piece of crap truck and now I'm paying for it

Boy I just love wasting my money

Guess it needs new rings

How much does a mild re build with new rings cost because I can pickup a used Engine with around 120K for like $1500 is a rebuild cheaper than that?

 

Slow down and have a cold drink of your choice then clean the battery terminals..... If that works re-check #4s compression.

 

That's funny it was a loose positive battery cable phew..........

I re tested the #4 Cylinder and it only went up to 90 PSI Dry and Put in about 15ml of oil and tested again wet and in went up to about 120 PSI

I'm just trying to get this truck to run good enough to pass CA emissions test but it most likely will fail if it has bad compression.

What should compression be expected to reach on each cylinder with 310,000 Miles anyway?

I ran out of time before it got dark and rainy on me but if I test all other cylinders and they read 130 PSI Then the 90PSI #4 Cylinder is about 70% of the rest so Isn't that technically acceptable lol????

 

I would expect to see all cylinders within 10-15% of each other.
I also would expect to see between 75-90#'s as okay or normal, not below.
Not sure how you're getting 130?

 

Don't give up yet.

Other things besides bad rings can cause low compression. i.e. a stuck or dirty valve, more likely is cylinder wash due to a stuck open fuel injector and/or repeated cranking of the engine without starting, etc.

I would give the cylinder a chance to dry out and re-test.

With that many miles, it could be a broken, damaged, ring on that cylinder, but I would want more evidence before condemning it.

More testing is needed before jumping to a costly conclusion.