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-   -   89 4.2 wrangler backfiring/choking out issue. (http://www.wranglerforum.com/f218/89-4-2-wrangler-backfiring-choking-out-issue-241474.html)

metalharo9187 05-09-2013 01:11 AM

89 4.2 wrangler backfiring/choking out issue.
 
Okay this started out as what I thought was an issue with blowing off spark. What would happen was while driving and the vehicle reaching about 1800-2000 rpms it would kinda cough and choke out and bog down. You could hear it wanting to backfire in the pipe, like it was rumbling. If I pushed the clutch in it would level out and be fine until trying to drive at that rpm again. If I up shifted it would be fine. So I went on a mission to systematically try and fix the issue, I changed the vacuum advance, the plugs from bosch plat to regular autolites, pick up stator, and finally the fuel pump. It is running incredibly better although now what it does is it sometimes will backfire when I go to start moving from a stopped position and when I shut off the vehicle. Any ideas guys?

kik 05-09-2013 05:42 AM

Your Ignition Control Module is probably going bad causing you to lose spark. I had to replace the one on my 89 4.2 2 yrs. ago. Yours is overdue to be replaced. You could still have a carb issue. I would replace the module and go from there.

metalharo9187 05-09-2013 07:54 AM

I replaced it two years ago.

metalharo9187 05-09-2013 07:58 AM

Also I believe they either work or don't.

metalharo9187 05-09-2013 08:33 AM

I just noticed that it now stutters when I shut it off, like it wants to keep running.

kik 05-09-2013 08:34 AM

Quote:

Originally Posted by metalharo9187 (Post 3736690)
Also I believe they either work or don't.

That's not accurate. There are intermittent issues with them at times, especially when it heats up, externally, from the engine. Since you replaced it you could have a carb issue. I would try cleaning the carb, replace the fuel filter, and see how it is. Also, check your timing. Keep in mind that you could still have a bad module or you can have a problem with the sending unit pick up in the tank, or the distributor itself. It still seems like a fuel or spark issue. If you're still running an original carb it could be causing the problem but you're going to have to rule it out.

kik 05-09-2013 08:37 AM

Quote:

Originally Posted by metalharo9187 (Post 3736775)
I just noticed that it now stutters when I shut it off, like it wants to keep running.

With 89 4.2's that's usually caused by a timing issue or your idle is set too high. You should be at 750-800 rpm with a hot engine in park/neutral with a stock carb.

metalharo9187 05-09-2013 08:53 AM

Quote:

Originally Posted by kik (Post 3736779)

That's not accurate. There are intermittent issues with them at times, especially when it heats up, externally, from the engine. Since you replaced it you could have a carb issue. I would try cleaning the carb, replace the fuel filter, and see how it is. Also, check your timing. Keep in mind that you could still have a bad module or you can have a problem with the sending unit pick up in the tank, or the distributor itself. It still seems like a fuel or spark issue. If you're still running an original carb it could be causing the problem but you're going to have to rule it out.

I'm running a new weber and the fuel filter is also new.

Rmn42689 05-09-2013 10:55 AM

Ya I agree...check your timing. Engines still trying to run after shutting it off sounds like its off. I other than that I would say it could be ur power valve in the weber gone bad. But id check the timing first.

metalharo9187 05-09-2013 11:30 AM

Quote:

Originally Posted by Rmn42689 (Post 3737239)
Ya I agree...check your timing. Engines still trying to run after shutting it off sounds like its off. I other than that I would say it could be ur power valve in the weber gone bad. But id check the timing first.

Yeah it is possible in my changing the stator and vacuum advance I could have slightly rotated the distributor.

sevenservices 05-09-2013 03:45 PM

I would also look under the hood, in the dark and have someone hold the RPM's at 2,000 or so. Look for a spark... it could be a small crack in the plug wires jumping to ground. You'd see a noticable blue spark from the wires to the block/head/brakets/etc... Anything metal basically.

metalharo9187 05-11-2013 03:00 PM

Loose distributor and failing pcv, runs great now. Thanks guys.


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