Hey guys, hope you can help me out here I am gonna try and explain the best I can and see what I can get.

I recently changed my head, pistons and head gasket. I got it all back together and now I am showing a cylinder one misfire. I have replaced the injectors with the Dodge caravan injectors. That did not do anything. I noticed that the wire was showing bare wires and swapped the wires. Nothing. I had also changed my spark plugs. Nothing. I changed the cylinder one coil spring and boot or whatever it is called. Nothing happened.

I reset the computer each time I changed something and every time it seems to run ok for a mile or two than the check engine light blinks for about 10 times than is constantly on and the same 0301 code. It will blink if I press the gas to speed up a little.

Also I can really feel it missing if I am at 45 to 55 mph and cruising at that speed.

I think I covered everything. I have not done a compression test yet either. Please let me know if you have any ideas. Thank you the help!

 

I had a p0300, multiple random misfire, on a brand x vehicle. Ended up having to replace the coil packs. If the coil pack was bad I would think the paired cylinder would miss fire too though. Aren't these set up as a wasted spark system? Maybe one of the more knowlegeable types will chime in here.

Don't rule out a bad/cracked spark plug. I knew a guy once put new spark plugs in only to have it misfire. Turned out he cracked the porcelain on a new plug. It was some random guy down the road... really!

Rodger

 

I put 6 new ones in. After it started to miss I swap ed that front one. No dice on that.

 

Seems like the primary suspects would be the coil rail itself or something internal (compression test not a bad idea).

 

What is the best way to test the rail? Taking it off and the boots see if they are all sparking?

 

Bump

 

Found this looks a little dangerous but it worked.....

 

Ya I seen it to. If I knew how else to test them I would rather do that with a multimeter to get an accurate ready. Just don't know the specs

 

This shows individual cylinders firing best test i can think of . Your issues gonna be its intermittent . Maybe connector to coil rail dirty ?

 

Buy a factory service manual! It has come in very handy for me more than once!

 

Do the compression test first!!
I wasted 6 months and $200 of other "Fixes" before I did the compression test to find out I had a burnt exhaust valve.
No amount of changing plugs, boots, springs, coil packs, valve springs, (yes I tried that too) injectors, or computers will fix a burnt valve.
And just because you just put a rebuilt head on recently is no guarantee that a valve or even piston rings aren't the culprit.


DO THE COMPRESSION TEST!!

 

Ok I will try one. I know the valves and springs are good tho. I checked them out too. And a buddy of mine looked at them. I will.do a compression test and let you guys know the result.

 

Could I do a drop test? Would it be the same think?

 

Do you mean a cylinder leak down test? A leak down test is better because it tells you more than a compression test. The results will be more accurate if the engine is warmed up.

 

Ya. I may try both. If it was an exhaust valve would only one cylinder be missing?