So i've got a 97 ram with a 318 and I'm having daily recurrences of cylinder number five misfires. Anytime I go up a long hill or push the truck above 3000 RPM with the transmission kickdown, my check engine light flashes at me during, and for 30 seconds or so after I let off. High end acceleration is almost non-existent as it seems to take hours to get up to seventy unless im going downhill. I've done a full tune-up (plugs, wires, cap and rotor) in hopes of curing the issue but to no avail. I also changed out the fuel pump less than 3000 miles ago. Any ideas?

 

check your plenum gasket

make sure you followed the tps routing for the wires

compress test for creaked head

 

Clogged cats can cause a misfire under load.

 

need to do a compression check to rule out "the unspeakable"

 

The only time that I know of that the engine light flashes is in an extremely "lean" condition. Probably why it only comes on under load.

 

Compression test revealed a cracked cylinder head at #5. "The Unspeakable" has happened. I'll replace it in a few days i guess. What a pain in the ***. Thanks for all your help.

 

I was going to agree but see that cylinder #5 is cracked.

 

ouch! PLease tell me you are going to replace all. Hate to see you with another. The cracked piston was probably a result of a lean condition. Something you might want to check when you get done.

 

Now, hold on just a minute. Did they / you pull the head to verify this? Is there physical evidence that you can see. Having little to no compression could be MANY things including a bad valve seat or, blown rings at the piston or, valvetrain problem involving a weak valve spring etc.



* How do you know for sure (unless you've pulled the head and dyed it) that you've got a crack at CYL No 5? Not that it's impossible as Dodge Magnum heads are notorious for dry cracks but, usually, in the rears at No 7 & 8 mostly but, I'm asking as to how you cam to that conclusion just from running a compression test.


CM

 

I'm honestly not too saavy as of yet when it comes to messing around with my engine. We did the compression test at my mechanic buddy's house and since the cylinder didn't hold pressure, it was just assumed that there was a crack at #5, which could also explain the fairly substantial amount of coolant consumption, right? As for the plenum gasket being the issue, wouldn't i be consuming oil? Also, could the lean condition be caused by a fouled injector at #5?