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post #1 of (permalink) Old 01-04-2001, 05:35 PM
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What do I do to my dist? if:

I have a 88 yj 4.2L carter/5spd/
The timing will stay normal and advance in acceleration as normal off the begining of the drive.
(It runs the best I have ever seen in a long time!, givin it has the carter and stock ignition)
But around aprox10-15 min of driving and running it, the tach will go nuts(waves between 1700 and 5000RPM) above 1500RPM, (the timing seems to jump to max mechanical advance at that speed), it will knock/ping but usually returns to nice idle. when this happens it will run like normal, only up to around 1500RPM.
I tried to slowly rev it up to 1600RPM, it went smooth, up to there then started to knock, lightly. I kept my foot as the same spot and the motor took off knocking exessivly! the tach was in the 4000's, but it was not physically.
What causes the mechanical adanvce to work?, could it jam up?What does the PICK-UP COIL do?
I actually made the worst things about my jeep go away(No hesitation, No missing, No power lack, Perfect idle and runs smooth to redline) , untill this.
-This is not a vacuum advance problem
-This is not an Timing chain/Gear problem
-I performed a computer bypass, of ignition and carb.
If you guys want any more info to make a guess, cause I have no idea what to do, just followup a question or whatever.
I really think it has to be bad to run the engine at 40*advance.
Oh yeah, any suggestion would be great, cause I don't really have 150$ just to toss away for a new one.
Thanks from MATT88YJ

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post #2 of (permalink) Old 01-05-2001, 01:05 AM
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Re: What do I do to my dist? if:

[img]/wwwthreads_images/icons/smile.gif[/img] This is a question for TeamRush. TR would be able to tell you what is going on.[img]/wwwthreads_images/icons/crazy.gif[/img]

Quadra-Tracs modified While-U-Wait by the crack moonguy[img]/wwwthreads_images/icons/wink.gif[/img] Quadra-Trac Team.[img]/wwwthreads_images/icons/tongue.gif[/img][img]/wwwthreads_images/icons/smile.gif[/img]
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post #3 of (permalink) Old 01-05-2001, 10:20 PM
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Re: What do I do to my dist? if:

My theory is that it's either a bad ignition module or maybe a bad ground to the ignition module. The amount of voltage/current going to the tach determines how far the needle is deflected. Your tach is connected to the ignition module output that goes to the coil. If your tach is reading a higher RPM than your engine is actually running, your probably getting some spurious voltage in that circuit that is also causing your coil to fire at the wrong time. I'd be real suspicious that your ignition module is causing the problem.


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post #4 of (permalink) Old 01-06-2001, 05:14 PM
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Re: What do I do to my dist? if:

The ignition module theory would be correct for only aftermarket tachs...
He didn't say if he had a factory tach or not.
If he does have the factory tach, it's probably the tach it's self causing the problems.

AMC tachs are notorious for causing ignition problems that get blamed on the ignition system....
It was AMC's bad design for a tach (meant to work with the Prestolite ignition, and scabbed into the Motorcraft/ DuraSpark ignition).
Until we have more information, there is no way of knowing...

He needs to disconnect the tach and see if it still does it...
He needs to check is wiring connections on both the tach circuits and the ignition circuits...
He needs to do a resistance check on his ignition wiring harness...
He needs to do a resistance check on his ignition coil...
He needs to do a resistance check on his distributor pick-up coil...

And he needs to post the results here so we can figure things out.

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