Issue: P0308 code.
I have a P0308 code/#8 misfire that will NOT go away!
I've read what seems like every page on the internet about this code but nothing seems to be working. I installed new coil, wires, plugs, cap and rotor. Swapped out #8 plug and wire, still got it. Next up, compression test... all came back fine. Low 155, High 170. Sprayed carb cleaner looking for vacuum leaks, found nothing. Ran Sea Foam thru vacuum, gas and oil (idled 15 minutes before oil change) made it run much smoother but still got the code. Injector seems to be working fine as well. Replaced upper and lower o2 sensors. I have been clearing the code from the computer and going thru the drive cycle but the code returns.
Being so frustrated, I broke down and paid $104.00 (*for nothing!) and took it to the Dodge Dealership. They had it for 2 days and also could not find the issue. They said everything seems to be working perfect for a truck that has 130,000 miles. They suggested that I replace the ECM/ECU but they weren't making any promises that that would be the issue. *Thanks for nothing guys!
Anyways, I'm at wits end on this and have to pass an emissions test ASAP. Any thoughts would be greatly appreciated.

Thank you in advance!
M.

 

Replace the cylinder head. The cylinder head crack between the valves and cause a misfire.

 

If its a cracked head, wouldn't I have low compression?
M.

 

I ran a block test... came back negative. No exhaust gases in coolant.
Dealership ran compression test on cylinders, all passed.

Not sure where to go next.
Frustrated as hell!!

 

Hello,

I feel like this may be my moment to shine-but I don't want to jinx myself.

The plug wires of these model years of Dodges require very specific plug wire routing-and even specific routing of the connections at the distributor cap.

http://www.ramforumz.com/showthread.php?t=46269

I had a misfire on plug #4 after I replaced the plugs, wires cap and rotor. I also checked compression, felt the FI pumping fine, pulled the #4 plug and found no issues.

I re-routed the plug wires as described in the link, check engine light went out after a half hour, two weeks later still no issues.

Give it a try.

FWIW, I've restored several vintage tube amplifiers as well as built my own from scratch. Electricity is an odd beast sometimes, giving very unexpected results for seemingly mysterious reasons.

Best,

Heekma

 

Matthew I know this sounds strange but heekma is correct the wire routing is very important and being a guy who has owned 5 dodge vehicles is should make it go away.
The other thing that you can do is to buy premium grade wires that drag cars use and that combined with the plastic sleeves that go over the wires should help also.
IF that does not help then your computer is taking a Sh*t on you

 

Your distributor does have a hall effect sensor inside of it and it also times the fire order of the spark plugs and that get relayed back to the computer and if that is going bad then you might have to replace that part or the whole distributor.

 

Thanks Guys!
I did rerun the coil wire yesterday but not the path that is shown in the pic.
I will try this today as with all the others.
Also, I do believe I purchased decent brand of wires/plugs/cap/rotor but you tell me... http://www.amazon.com/ACCEL-TST24-Tr.../dp/B001DUD1UC
I also replaced the covers from the old wires onto the new ones.
Lets hope this works!
M.

 

Shine you did, Heekma,
Where were you a month ago?!! LOL
Just like you described... I rerouted the wires per you diagrams and within 30 minutes, the CEL went out. I am in the middle of the drive cycle waiting for the CEL to light up again. Lets just hope it doesn't!!
This was previously suggested to me but I had no idea how to place them. The diagram was perfect!! Thank You!

I'll keep you posted on the outcome of the drive cycle!
M.

Hobbyart17, if my hell continues, I will follow up with your suggestions!!

 

This nightmarish forum strand is OVER!!!
After routing the wires as shown in the pics supplied by Heekma (no jinx, your record continues), the CEL disappeared within 30 minutes and today I PASSED my emissions test.

Thank you to everyone that helped me on this. I will say that your suggestions made me smarter and helped make this run a lot better/smoother than it has in years! Thanks!

Thanks Again Everyone!!
Matt

PS. I will be going back to the dealership to inform them of what the cause was and express my displeasure with their $104.00 service for nothing!