Cylinder 8 misfire - burned valve?

05ram4x4 · Jul 13, 2014

Alright, I checked compression today and cylinder 8 was low again, just like before. So I ran some seafoam through it, and the idle smoothed out a bit. Smoked quite a bit when I ran the seafoam through, so I'm thinking carbon buildup is the issue, again! Why could the carbon build up so quick on cylinder 8? Could the cat cause that?

Merc225hp · Jul 13, 2014

Take it back to the shop tell them the problem is back, tell them the tune-up in a can thing is not working.

The heads need to be pulled, de-carbonized/rebuilt and odds are good the plenum gasket is shot, along with the cat and 02 sensors.

05ram4x4 · Jul 13, 2014

Plenum is fine. I changed that after I bought the truck myself. Ill give them a call tomorrow. But the code hasn't come back yet.

dodge dude94 · Jul 13, 2014

Bad valve seats possibly?

05ram4x4 · Jul 14, 2014

Any ither things I could check or do myself? Before I hand it to them and get charged.

05ram4x4 · Jul 18, 2014

Any ideas?

05ram4x4 · Jul 21, 2014

No help?

Jsinclair92 · Jul 24, 2014

A bad plenum gasket can cause a cylinder 8 misfire

05ram4x4 · Jul 24, 2014

I've already said that I fixed the plenum issue before this came up.

05ram4x4 · Jul 26, 2014

Any other ideas guys? I swapped injectors today with no difference. I'd really like to try as much as I can myself before handing it over to the shop.

dodge dude94 · Jul 27, 2014

Remind me what the compression test results were.....? lol

05ram4x4 · Jul 28, 2014

If I remember correctly, it was about 60 for cylinder 8 and about 130 for cylinders 2, 4, and 6. This was using the tester from autozone, which doesnt rear quite correctly.

Im going to try to find a compressor to use and do a leakdown test.

05ram4x4 · Aug 1, 2014

Alright, I did a leakdown test, and it was gushing air out of the throttle body. That's with the cylinder at TDC(to the best of my knowledge) So that leads me to believe the intake valve is bad. Is there any way I can check that for sure myself? Just to confirm it? I don't want to bring it to the shop and have them tear it all apart to find out it's not that, then charge me like crazy, because otherwise, it'll be under warranty and I pay nothing.

05ram4x4 · Sep 15, 2014

Alright guys...it's been a very long month, and then some. But my truck is fixed! Shop found low compression in cylinders 6 and 8. Took the head off and found it burned. Sent both heads to a machine shop, and they said the passenger head was unfixable. Cracked. Took forever due to issues with their employees, but I have her back like new! Just passed 80k miles the other day.

dodge dude94 · Sep 15, 2014

Sounds about right. The right bank head likes to crack much sooner due to being closer to the cat. So when it clogs backs heat up into that head sooner. Good to hear it's fixed now.

05ram4x4 · Sep 15, 2014

Now I can start the mods!

dodge dude94 · Sep 15, 2014

Like a Mopar M1 and HS1.7rrs lol

05ram4x4 · Sep 15, 2014

What in the world is a HS1.7?

dodge dude94 · Sep 15, 2014

Harland Sharp 1.7 ratio roller rockers. They act like a mild cam.

Something like a 20 hp 20 ftlb bump in power. :naughty:

05ram4x4 · Sep 15, 2014

Sounds awesome but they are pretty expensive!

Cylinder 8 misfire - burned valve?

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