Cyl 6 misfire again

[riverjig]

I have searched multiple threads and the ones that seem promising, stop without the end solution. I have a 1996 4.0 and have had multiple issues trying to get it to smog. I have replaced an o2 sensor, spark plugs and spark plug wires. After this, truck was running fine and then a code got thrown saying cyl 6 misfire detected. I took it to a shop and they said the spark plug wire to that cyl was faulty. So replaced it and seemed to be fine. I continued trying to complete my drive cycle and after about 100 miles, check engine light came on again. Cyl 6 misfire detected again.

I already payed someone to diagnose my spark plug wire which seemed like the biggest waste of money ever. I dont know what my next step should be. I would appreciate any help.

 

[Big Jim M]

I'd start with another new plug for #6..
Big JIm

 

[modelageek]

I'd start with another new plug for #6..
Big JIm

after you throw a new plug in.....add a large bottle of Techron to the fuel tank

 

[riverjig]

ok. im just gonna get all new plugs, even though the ones i have are pretty new but not the factory specified ones. New plug wires since they are warrantied, and a bottle of techron. Go from there. Thanx. Keep you posted

 

[4.0L2WD]

Make sure you have your plugs going to the right slots on the cap.
Make sure your plugs are gaped correctly.
Buy a cheap compression gauge from harbor fright and check the compression on each cylinder. It's pretty easy and affective. It will tell you the PSI of each cylinder under a load.

Run some engine honey if the cylinder is low on comp.

 

[shane96ranger]

Had the same thing happen to me, but cylinder 4. First go around it was the wire. I did change the plugs at the same time. Six months later, I had the cylinder 4 misfire again and it was the plug. I guess maybe it was cracked, or I cracked it putting it in.

 

[riverjig]

ok. I replaced the spark plug wires and the factory spec'd plugs from motorcraft, gapped correctly. Well see how that does. Keep you posted. Thanks for the replies..

 

[riverjig]

Finally got the problem diagnosed

So after all of the diagnosing I did thanks to everyones help here, I decided to take it in. Just didnt have any more time to devote. Turns out it was an injector. After that being replaced, a week later, check engine light comes on. So, I take it back in. They do a compression test. Turns out cylinders 1 2 3 are at 100 psi which is fine. 4 5 6 are at 75 psi. SO they recommended that I get a new engine. Im not sure if thats the only option. I probably should take it somewhere else for a second opinion right?

 

[Big Jim M]

Oh yeah!

So after all of the diagnosing I did thanks to everyones help here, I decided to take it in. Just didnt have any more time to devote. Turns out it was an injector. After that being replaced, a week later, check engine light comes on. So, I take it back in. They do a compression test. Turns out cylinders 1 2 3 are at 100 psi which is fine. 4 5 6 are at 75 psi. SO they recommended that I get a new engine. Im not sure if thats the only option. I probably should take it somewhere else for a second opinion right?

I'd get me a compression tester and do it myself! Pull all the plugs, hold the TB OPEN and crank each cylinder till the pressure quits rising. If the first two are higher than the mechanic said they are, I'd start grinning to myself.
Big Jim