88 mj sputter and backfire no power

[ComancheGurl]

The deal is I have a 88 mj 4.0 auto trans PO beat the piss out of it so far I've replaced one pushrod,timing chain&gears,vacuum lines,etc. Took apart head and replaced a bent pushrod,brand new gaskets on the thing,all vaccuum hoses have been replaced within the last 3 months,all injectors are firing,after installing new pushrod it still acts the same. Also replaced fuel filter&pump.

Currently rebuilding another motor for it out of a 94.

Any ideas?? thanks in advance

[HellCreek]

According to my limited mechanical knowledge, en engine backfires when an intake valve is open at the same time the spark plug is firing. I would look at either the valve timing or the ignition timing -- or both. Or, if you changed the plug wires, check the firing order.

 

-Tom

[carnuck]

pump it for compression

[JeffN]

if you bent a pushrod you may have bent the valve, run a compression test on the cylinder to confirm

[ComancheGurl]

Timing is good. Different cylinder head so i'll check the valves and run a compression test. Firing order is correct.

[Eagle]

If it's backfiring, it is virtually 100 percent certain that the timing can't be good. Check it again. Be sure #1 is at top dead center ON THE COMPRESSION STROKE, then check the distributor to see if the rotor is pointing at the #1 terminal in the cap.

[ComancheGurl]

Already did that. It runs fine at idle but sputters when you step on it hard.

[raviolli]

clogged catalytic converter? :dunno:

[carnuck]

Rotor may need resetting in the dist.

[ComancheGurl]

The exhaust system seems to be in good shape but ill check it anyway. And ill check the setting of the rotor as well.