hi folks! well, working on a '91 might max 2.4 for a friend, and it was running super rough, hard start, etc. i did lots of things, swapped a bunch of parts with a '96 mighty max parts car, and finally swapped the entire exhaust manifold/catalytic converter. this fixed the main issue -- i think it was a warped manifold leading to clogged cat. however, during the process i changed the distributor timing, and didn't have a timing light so had to set it by feel.
things were a lot better, but still having very weak power at low RPMs or on hills (under load). i suggested not to drive it much until i got a timing light, but i think it got driven at least a couple hundred miles.
got the timing light, and the timing was way advanced, i think. like 15-20 degrees (!?!). i was jumping the wrong jumper at first, so that was the post-computer timing. now, with correct jumper, the timing is a steady 7 deg BTDC. however, with jumper ungrounded, it jumps around from ~9 degrees to ~14 or so. like a lot, not smooth, like each rotation is a but different. not sure if that's normal?
anyway, now it starts well and everything is a lot smoother -- but still getting pretty terrible power at low RPM under load, and also backfires. not huge ones, put pretty frequent coughs/puffs of smoke. i drove it for ~10 miles to see if the computer just needed to reset, but not much change.
any thoughts what this might be? computer issue? (should i try swapping the '96 computer back in again?) sensor? (o2? it's the one from the working-but-low-compression '96.) gunk in the compression chambers?
appreciate the help!
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