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87 MJ 4.0 auto running issues...loose dizzy? FIXED

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ok, I've got a 1987 jeep comanche i picked up a while ago and I need it done next weekend...this includes lifted, new brake hose, new rear line, bypass MJ prop valve, install interior, SOA rear, and 4wd swap.


it doesn't run right.


idles great. sputters at accel. won't accel past 1700 RPM without sputtering/coughing but it doesn't die out (just backfires like a mofo)


so far I've replaced the fuel filter, put in premium gas, replaced the throttle body and it's sensors, plus MAP sensors, and CPS. none of this has helped.


removing the vac. line from the fuel rail doesn't really do much.


but, looking at it running the other day, i noticed the distributor bouncing around. (wobbles slightly). when the truck is off, I can turn it about 1/8" and wobble it back and forth.


...now i KNOW this has to do with my running issues, but does anyone know the symptoms that problems would cause? I haven't replaced the dizzy yet cause of the problems with the 3800 this weekend, but just wondering what everyone thinks of this issue.

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The whole distributor itself? Yeah that's definitly a problem. Did you check to make sure it's bolted down all the way?


haven't had the time lol.


I'll do all that tomorrow, and probably install a "new" distributor and re-time it to TDC on number one to be sure.


just haven't had the time, and only just noticed this the other day...when it did run (a fusible wire broke so i've got to put a new fusible in)

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Your description sounds like a timing problem. A loose distributor could definitely cause this.



It was exactly that kind of issue that led the factory to issue the TSB about "indexing" the distributor.

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well, tightening it down in multiple locations (it spins a bit...) didn't fix the problem...although I can now rev to 2000 RPM instead...


when I remove the vacuum hose from the fuel pressure regulator, it does nothing. :cry:

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thanks everyone...I advanced the distributor by one tooth, and MAN does she run like a CHAMP!


exactly what happened to me...idled perfect...ran like piss above 1500RPM....glad ya fixed it 8)


me too. I'm dropping a 4.0 into an xj on saturday morning, then beginning to lift this thing saturday afternoon...i need to get in at least a couple weeks driving before i go down to the badlands with it, so even if I don't get the 4wd tranny in it until the following weekend, I'll be driving it.

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