I have an 89 YJ with a 4.2L. I have put on a motorcraft carb, 10"x4" K&N air filter, done the Nutter Bypass and eliminated all of the emission controls (plate behind EGR valve, plug in cat, etc) she starts and idles fine, but as I was going to drive to work, as soon as I started putting a load on the engine it died. I put a new fuel filter on it, that didn't help. so I changed the coil, that got it so that it would'nt die under load but it hesitates really bad unless I really get on the throttle. I replaced the cap, rotor, plugs and wires and re-timed it to 12 degrees advaned (it was at 18 degrees) and it made a small improvement, but it still hesitates and sputters unless I am accelerating hard (it sounds like it's running on three when I am maintaining speed) and when I downshift, it sputters really bad for a few seconds until it catches and then it does ok, until I try to cruise again. I am at a loss on this one, any thoughts?
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- Thread starter Magua308
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Bounty__Hunter
Super Moderator
Does it seem to do worse as it warms up? Could be a clogged catalytic converter choking the engine. Happened to my '88 4.2L back in the day.
This just got really weird. I made all of the adjustments I noted earlier yesterday and took it for a test drive, and it still ran like crap, so I just went to bed. When I got up this morning to go to work, it ran PERFECTLY and has ran great all day. So, I think my YJ has a healing factor or some other mutant super powers. (I actually get really nervous at self-fixing problems, I hate not knowing exactly what is going on)
