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Discussion Starter · #1 ·
ok, I have a 04 DII with about 110k km. ran great, then a cylinder 5 misfire code. Plug was dirty/sooty when I pulled it.
What I've done:
New Ngk double platinum plugs - no change.
New Ngk wires, new #5 injector....
Now I have a misfire on 5 and 7! WTF!

I read something about plugged cats causing back pressure issues causing misfires. Noticed 5 and 7 fire right after each other, went out on a limb thinking maybe too much back pressure. Disconnected SAI on that side to let some more exhaust out. - NO CHANGE.

thinking compression check next.

Ideas?

Thanks.
 

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Discussion Starter · #4 ·
Not the coil. Or highly unlikely. 5 and 7 are on different packs. 5 shares with 8. 7shares with 4. If the coil was the problem on my initial #5 misfire I should have also had a misfire on 8. I'm no pro but did a lot reading.
 

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Discussion Starter · #5 ·
Update: I did a compression test and found the following:
Cyl1: 190 psi
Cyl3: 175psi
Cyl5: 25psi
Cyl7: 55psi
The right bank was consistently high. I didn't disconnect the fuel injectors so the cylenders were filling with gas. Blowing them out with compressed air brought them down close to spec. I'll check them again when I get the intake off and the injectors unplugged.

Ordered the head gasket kit. Hopefully I don't find anything else when I get the head off. Anyone ever had problems with stuck or burnt valves? I'm hoping to find all mine in good shape.
 

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That's a bit of a bugger!
thanks for updating us - post some pics of the damage. I have not heard of many problems with stuck or burnt valves but there is always a first time. As there is no oil in water and you are not losing water I would assume (hate doing it) that the failure is between 5 and 7 rather than the oil or water galleys - make sure you check head and block for erosion.
good luck
cheers
Barri
 

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Just a thought....
I have never had one fail on me but have you considered a rocker arm / rocker shaft? Seems to be a semi common issue.
You mentioned the possibility of a stuck or burnt valve (valve not closing) maybe you have valves not opening?
May be worth you time to pull the drivers side valve cover off and having a look
 

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good thought redtruck12!
must have been 3 or 4 posts in the past 6 months on broken rocker arms - I had forgotten about that.
 

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Discussion Starter · #9 ·
Thanks for the ideas. Fortunately (or unfortunately, depending how you look at it) I had a leaking right side valve cover gasket when I replaced the wires. So while I had the upper intake off I replaced both valve cover gaskets. I gave everything a good look over and did not see anything that would indicate valve problems. Thanks again.
 

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Discussion Starter · #10 ·
I know it's been a while but life can get busy. Anyway, she's all fixed up. Confirmed head gasket blown. Had the heads both refreshed, (surfaced, valve seats really cut, new valve seals). Put I all back together with arp studs. Stripped 3 head stud holes in the block! What a pain. Can't help thinking arp's recommended 100 lb/ft is a little high for the aluminum block. Helicoils to fix those holes. All new gaskets etc. New plugs. Magnecore 8.5mm wires. And didn't bother putting the Sai pipes back in. Left the pump and solenoid on for now to reduce the dtc. Suprised cel only comes on about once week for Sai system. I check and clear the codes every so often, no biggie. All this was finished in December. I was glad to have it back on the road for the winter. Thanks to everyone who threw out ideas. Much appreciated.
 
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