Tapping and small backfire

[greenmachine89]

I've owned my Ex for about a year now and ever since I've owned it it has had this ticking or tapping noise. I've tried everything from different gas, cleaning the maf, tearing the whole top end off to check the lifters(which I replaced two of them), seafoam, thin oil, thick oil, new plugs, wires, etc. and yet my gas mileage sucks only 12 mpg at the best! Now I have noticed that when I sit at a light stopped I can hear a small backfire in the exhaust underneath the floor boards. So i checked the exhaust and all is good, no leaks. The small backfire I hear is inside. Almost like the timing chain jumped a tooth like the timing is too far advanced or something. If anyone has ANY ideas please let me know! I love these EX's but if this thing keeps it up, time to take it to u-pull it and leave it!

 

[DOHC4]

Sounds like you have a cylinder that may not be firing from what your saying. Correct me if I'm wrong.

 

[greenmachine89]

So would that sort of problem be involved with my coil pack?

 

[fordnut71]

i had a problem like that years ago from a old 300 i-6. found out that the push rod had partly fell out of the rocker arm groove.so it was keeping the valve partly open at all times.

 

[greenmachine89]

But i changed the rocker arm assembly out with a new one with new rods and everything and it still does it

 

[4x4xbrian.com]

the back fire could be a burnt valve..... I've seen a few on 4.0's
as far as you tapping how are your rocker arms? tips worn?

 

[greenmachine89]

I just changed the rockers out all brand new. As for the valve that means tearing down the whole top end again! I guess I could do a compression test to find it. I did look over the heads when I had them off and they didn't show anything out of the ordanary.

 

[fordnut71]

id do a compression test 1st to see if that shows anything before you tear into the motor.also see if you can do a leak down test. this will tell quite a bit on well the motor is running.