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Old 10-19-2011, 05:01 PM   #1
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Default 98 Cherokee 4.0 no spark

I have already tested the cps, it reads infinite ohms, I've tested the ignition coil and it falls within tolerance.

I recently swapped out the ecu for a new one but the no spark started when I was checking the leads to my second fuel injector- i would take it off it would run better, I'd put it back on and it would bog down, the last time I tested it the engine died and I have no spark.

I've looked everywhere on the vehicle for the ignition controller to no avail.

I'm kind of at a stand still here.
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Old 10-19-2011, 05:04 PM   #2
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The ignition controller is in the PCM, just replace the crank sensor and be done with it.
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Steering stabilizers will not cure or cause death wobble, they only mask the real problem that is causing death wobble. Oil pumps do not make pressure, they create flow. Bearing clearence and restrictions make pressure. It's the crank sensor.
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Old 10-19-2011, 05:16 PM   #3
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The cps costs about $80 are you sure this is the problem? I would hate to go on a pricy Easter egg hunt.

I guess what I am asking is there anything else I should check first?
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Old 10-19-2011, 06:09 PM   #4
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Try swapping the ASD (autoshutdown) relay with another in the power distribution center (black box under the hood on the passenger side). A long shot, but should be done.

The #1 cause of no spark on the 4.0 is the crank sensor. If you buy one, buy it directly from Jeep. There is no lack of threads with people that purchase an aftermarket one. It is well worth the extra money. Testing of the crank sensor is not always conclusive.

Another possibility is a faulty ignition switch.
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Last edited by tjwalker; 10-19-2011 at 06:39 PM.
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Old 10-19-2011, 06:58 PM   #5
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never discount the neural safety switch!!!!!!! had the cps and the neutral safety switch go wrong. cps was harder to diagnose...seeing as we had the neutral safety switch go previously. both cause no crank no start. so try the NSS could be loose. providing you have an automatic. im not sure how they are on manuals
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Old 10-19-2011, 07:15 PM   #6
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Quote:
Originally Posted by Mendax13 View Post
never discount the neural safety switch!!!!!!! had the cps and the neutral safety switch go wrong. cps was harder to diagnose...seeing as we had the neutral safety switch go previously. both cause no crank no start. so try the NSS could be loose. providing you have an automatic. im not sure how they are on manuals

Where would I find the NSS?

Nevermind found this great walk through of repairing the NSS on another thread:

http://go.jeep-xj.info/HowtoNSSrebuild.htm

Thanks you for the help!

Last edited by RevNed; 10-19-2011 at 07:30 PM.
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Old 10-19-2011, 08:05 PM   #7
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If the engine turns over with the key in the start position, the problem is NOT the neutral safety switch. The original post says no spark. That is not an NSS problem; the circuits are not related.

If the engine won't even turn over, that can be an NSS issue, as a faulty NSS can inhibit voltage from reaching the starter.
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Old 10-19-2011, 10:56 PM   #8
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So I swapped the cps and the asd relay, still no spark from the coil.



So what's my next coarse of action? Bear in mind I am working on a limited budget and I have already cut into it more than I should have.

By the way mine is a stick so the neutral safety switch shouldn't be an issue.

Last edited by RevNed; 10-19-2011 at 11:01 PM.
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Old 10-19-2011, 11:12 PM   #9
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Check for voltage at the primary side of the coil and check for a pulsing ground at the primary side of the coil when cranking. No voltage means there is an open in the circuit no pulsing ground means it is the cam or crank sensor not supplying a signal to the PCM.
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Steering stabilizers will not cure or cause death wobble, they only mask the real problem that is causing death wobble. Oil pumps do not make pressure, they create flow. Bearing clearence and restrictions make pressure. It's the crank sensor.
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Old 10-19-2011, 11:36 PM   #10
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I would also like to take this opportunity to point out that when it did run it was running richer than any vehicle I had ever smelled, I'm sure if I had put a spark plug in the exhaust it would have shot flames quite a ways. I have yet to figure out the cause of the rich mixture as of right now I just want her to run again. I do also know that the second cylinder's fuel injector had an open circuit so I intend to trace the wires once I get her to run again.

I don't know if this information may influence why she is behaving as she is.

Well that's all from me tonight, I'm sure I'll be on again tomorrow, thanks for all the help thus far.

Last edited by RevNed; 10-19-2011 at 11:38 PM.
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Old 10-19-2011, 11:50 PM   #11
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mine wont start either. i get no voltage on my ballast restistor with the key on. does that mean anything?
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Old 10-20-2011, 11:18 AM   #12
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Ok, where is the ballast resistor?
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Old 10-20-2011, 12:27 PM   #13
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Quote:
Originally Posted by RevNed View Post
Ok, where is the ballast resistor?
You have no ballast resistor on your 98. I believe 93 was the last year for those.
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Old 10-20-2011, 01:31 PM   #14
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I am getting a minute amount of voltage out of the ignition coil when I try to turn it over so I think I will take back the cps and get a new coil.
I will let you know how it goes.
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Old 10-20-2011, 04:17 PM   #15
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So I fished out the bolt that fell into the bell housing from trying to put on the old cps, got the old cps connected again- same reading from the coil with the new and old cps. It seams like the old coil is giving me a higher reading than the new one but still not enough to spark.

I know that my local parts store sells an after market ignition controller(http://www.oreillyauto.com/site/c/se...998&vi=1315943). So if I were to install the after market ignition controller would that bypass the issue I am currently having?
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