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Discussion Starter #1 (Edited)
I have issues. NEED HELP
The Cherokee works like a dog. It idles OK but upon tip in throttle it skips badly and backfires through the exhaust. Full acceleration it revs OK as well. Its a renix system and I changed a whole bunch of stuff to eliminate components. The stuff I changed are throttle body, cause the tips shows a part throttle at 0.27v. Intake air temp, wire broken. Crank sensor, watching it with lab scope it spikes at different times (and not a reference spot). Ignition coil/module, cause I had one so I used it. O2 sensor cause it was dead. Swapped computer and still no change. Fuel pressure is 30 psi Idle and it still acts up with regulator unplugged and 40 psi. Besides the Skip is too fast for fuel so thats why I'm concentrating on fire. At idle the spark will jump an Inch with blue spark, when its backfiring and running rough the spark will hardly jump 1/8 - 1/4 Inch this I think is not normal and might be a problem ? and its the same with the other swapped coil/module. plugs are new. Any suggestions and help is needed as for all this work done so far is for nothing.
 

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I had the vacuum line that went from the throttle body to the MAP sensor get hot and sag in the middle, in turn partially crimping the line. It gave me the same symptoms you are talking about. Might be worth a shot.

MIke
 

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Discussion Starter #6
Yee Haa
Found and fixed the problem myself.
Turns out the distributor was out of time. You cannot install them straight up I had to grind the lock tab off and advance the dist about .040" to get rid of the Skipp. Now it runs really good.
 

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Yee Haa
Found and fixed the problem myself.
Turns out the distributor was out of time. You cannot install them straight up I had to grind the lock tab off and advance the dist about .040" to get rid of the Skipp. Now it runs really good.
Well, that ain't the normal way to fix it, but whatevah, it werks (I guess). Hope you're not just masking a problem though....

Was sounding like vacuum leak or the MAP sensor line popping off to me.
 

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Discussion Starter #8
Well, that ain't the normal way to fix it, but whatevah, it werks (I guess). Hope you're not just masking a problem though....

Was sounding like vacuum leak or the MAP sensor line popping off to me.
The map sensor line is perfect and its got 18" vacuum.
So what would be your normal way of fixing it? come-on tell me I need to know if i'm wrong. Been there before along with everyone else.
 

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The map sensor line is perfect and its got 18" vacuum.
So what would be your normal way of fixing it? come-on tell me I need to know if i'm wrong. Been there before along with everyone else.
Well if the distributor was off a tooth, I'd just pull it out and move it over a tooth. No need to go grinding on the distributor body. A quick trip through the manual (even a Chilton's) will show you the right way.
 

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Discussion Starter #10
I never said the dist was out a tooth. I said it was out of time. All I did was advance it approx .040. This actually changed the fuel delivery, which fixed the problem. Ignition timing is actually controlled by the PCM via the crank sensor. There is a tech bulliton from Chrysler that explanes the process of removing the tabs of the dist and advancing the dist to correct the problem. Oh the problem is the balancer outer ring actually turns a bit so when you put the timing marks on #1 cyl it actully not at TDC therefor the dist needs to be turned. And that is the way to fix the problem. And due to the AITN, Carquest Identafix websites ther is alot of Tecnitions doing this very same repair/fix.

Thank you :flipoff2:
 
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