Rep Power: 0

So, my 350K 1993 LX threw the crank pulley. Long story short , just replaced the motor with same type 150K from junkyard. Guy said it "ran"...:-( it runs, but backfires in the intake manifold, plugs 2 and 3 black soot, low power, won't idle right. When I pull off the plug wires 2 and 3 no effect on the motor. When I pull off 1 and 4 it stalls. compression test shows @ 190 on all 4. Changed injectors 2 and 3, no change. When i was changing injectors the injector ports for 2 and 3 had a ton of carbon buildup around them compared to 1 and 4. Its not blowing smoke. No CEL shows up. can't think of anything else to do. I have the old motor which ran fine, thinking of swapping heads, including manifolds to shotgun the problem. anyone has any other ideas? I really like my little beater... Thanks

 
Rep Power: 519

Firing order? Plug wires 2 and 3 got swapped?

 
Rep Power: 0

nope, 1342 also i checked the timing and its spot on...

 
Rep Power: 519

Did you switch the wires anyway just to be sure?

You say it has good compression, and there has to be fuel of some sort because it's turning plugs black....
Check valve adjustment?

 
Rep Power: 0

yeah did that, and its also backfiring out the intake but only on acceleration.

 
Rep Power: 0

gonna check the valve adjustment tmrw. Thanks

 
Rep Power: 519

Are the plugs 2 and 3 (center cylinders) just fouled and can't fire?
Did you try swapping the two center plugs with outer plugs (1 and 4) so the centers have somewhat cleaner plugs? (or swap in fresh plugs from other engine......check gaps too.)

Are the plugs wet and black, or dry and black?
If wet, can you tell what the wetness is? (oil, fuel or coolant)
Check if the injectors are being held open by the computer or a wiring problem?

Does the engine have an EGR valve? Unplug it (electrical or vacuum) so it cannot work, and see if it gets better.
If the EGR passages get real hot right away after startup, the valve may be stuck open.

Just trying to think of weird stuff here.

 
Rep Power: 0

Plugs are dry and black, just the cylinder 2 and 3. i just put new plug wires and plugs in. Swapped the distrib from the one I was running on the original motor, changed injectors 2 and 3. No change. Did the EGR check , yep stalls out when unplugged. basically out of ideas, gonna bring the valve clearances into spec and take it from there. Prepping the old head wi manifolds now...last resort going to swap heads.

 
Rep Power: 0

Well, the valve adjustments were all a bit loose on the intake side. Tightened them up to .007- .009. The exhaust side looked good. I'm gonna call this one Uncle and try to take this motor back under warranty

 
Rep Power: 519

Did you get the engine locally?
Maybe see if they can figure out why it's missing before you yank it back out.

 
Rep Power: 0

Problem solved...I had the plugs on 2 and 3 swapped...really thought I had looked at that many times. I think i was looking at the distributor and thinking it was rotating the "wrong" way, which would make sense that 2 and 3 would be swapped. 1 and 4 would always be in the same relative position tho. Ugh!...anyway the $100 I had to shell out was a ok price for stupid ...thanks to all who replied. Peace