mis-fire for one cylinder below 2000rpm, HELP?

[sloth69mustang]

my truck is a 97 but i did this 4 or 5 years ago. so its very possible. and i had some power lose but it was still drivable. the seafoam could have probably helped it. i am just saying check it to make sure its not a compression issue. and to be honest it only took me like 2 days to do the heads in and out. i wasnt in a shop. it was at home before i even worked in shops. so 0 air tools.

 

[dasfinc]

my truck is a 97 but i did this 4 or 5 years ago. so its very possible. and i had some power lose but it was still drivable. the seafoam could have probably helped it. i am just saying check it to make sure its not a compression issue. and to be honest it only took me like 2 days to do the heads in and out. i wasnt in a shop. it was at home before i even worked in shops. so 0 air tools.

I don't have 2 days to committ to a 10 year old truck that I could sell for a 100% profit margin as it sits honestly...

 

[sloth69mustang]

i guess i just enjoy my truck too much to let it go. i will never get rid of my truck

 

[dasfinc]

Well, I replaced the injector, cleaned the hell out of the other 5, cleaned the rail, replaced the gaskets, and cleaned everything else like 3 times over... Idles smoother, but still has the misfire....... Going to compression/vac test it tonight and hope for the best....

 

[feellnfroggy]

For our trucks a single cyl misfire is possible from a bad coil. Also a single cyl misfire 'at low rpms" could mean water in the cylinder? You have to read the plug. It could be a loose wire, bad ground many reasons possible. Now Im gonna go read the last page and see if you fixed it yet, lol.

 

[dasfinc]

For our trucks a single cyl misfire is possible from a bad coil. Also a single cyl misfire 'at low rpms" could mean water in the cylinder? You have to read the plug. It could be a loose wire, bad ground many reasons possible. Now Im gonna go read the last page and see if you fixed it yet, lol.

There are 3 coils for the 4.0 OHV,

All 3 secondary tested good, so did the primary

No water in the cylinder.... Dunno how having water in the cylinder would cause anything except a pitched rod??? Wires and plugs are new. The plug I pulled was 'cleaner' than the rest.

 

[dasfinc]

Stupid question... but if it fails the compression test, shouldn't it/wouldn't it be burning oil? Ditto with the Sticking valve? That spark plug was clean as a whistle....?

 

[feellnfroggy]

Water prevents combustion. At higher rpm it burns the water fast enough that its not building up enough to wet hte flame so to speak, but at low rpm the water is building up in your cylinder. Water is used with methanol injections to keep cylinder temps low, the water cools and the meth burns well enough to offset water in hte cylinder. water and fire dont mix. I would seriously check for head gasket leaks or warped/cracked head, has it ever been overheated before?

 

[dasfinc]

Water prevents combustion. At higher rpm it burns the water fast enough that its not building up enough to wet hte flame so to speak, but at low rpm the water is building up in your cylinder. Water is used with methanol injections to keep cylinder temps low, the water cools and the meth burns well enough to offset water in hte cylinder. water and fire dont mix. I would seriously check for head gasket leaks or warped/cracked head, has it ever been overheated before?

Never overheated that I'm aware of, and the coolant/oil are definitely not mixing, and it doesn't appear to be burning oil either, especially in cyl#1 where the mis is, that spark plug was CLEAN.

 

[dasfinc]

Thank christ....

Vac test passed, Compression is good, Replaced the coil pack out of futility, and that fixed it.