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Unread 04-01-2014, 12:06 AM   #1
i6zombiejeep
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1998 ZJ 
 
Join Date: Oct 2013
Location: Bend, Oregon
Posts: 81
Crankshaft Position Sensor Question

So I recently, like four months ago, changed my crank pos sensor. It was nice for like two days, but then the Check Engine light came on and sometimes flashes when the engine goes into higher revs.
When I replaced this, I did not put a small metal bracket back in. I decided to run without because I thought it was useless and too hard to put back in.
I checked the codes and I've got a misfire on all cylinders except #5 and something else was wrong but I forgot what it was. New plugs, wires, cap and rotor didn't help, besides giving it a little more power I think.
Now I am thinking that the metal bracket that was on the sensor originally was actually some kind of spacer to allow for more of a gap between it and the transmission housing...
Will putting this little metal piece back in solve all of my problems, or is it something else? Call me lazy, but that little sensor is a PITA to mess with and would like to avoid ever touching it again...

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Unread 04-01-2014, 12:54 AM   #2
Uniblurb
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1996 ZJ 
 
Join Date: Jan 2012
Location: Central, Ohio
Posts: 3,397
If you went with an aftermarket crank sensor rather than a Mopar one that's most likely your problem. Two brand new aftermarket ones from a local parts store in my 96 4.0 functioned just as erratic as the bad OE one and drove me nuts. Run the below test as a link in my signature using a an ohm-meter set to the lowest ohm setting and you'll probably find your new one tests bad if it's aftermarket.

It's not a good idea to leave the metal shield off the crank sensor since it's there to protect the wiring. I've installed them about 4-5 times and use a little bit of that sticky window rope caulking to hold the bolt/shield/sensor in the socket while installing from the bottom. Also tape your swivel loosely with electrical tape so it doesn't drop down too far. Doubt if the little bit of space between the sensor and trans bell housing, w/o the shield, is going to make a whole lot of difference since the hole is tight enough it seems to hold the sensor itself straight. Good luck!
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96 4.0 ZJ Laredo, 2004 4.7L WJ Limited, 93 4.0 XJ (spare), 96 4.0 XJ (son's)

-Stalling ZJ? 12 things to check before replacing a sensor; the Dirty Dozen
-Crankshaft position sensor multimeter test. & video of testing.
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Unread 04-01-2014, 04:07 PM   #3
i6zombiejeep
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1998 ZJ 
 
Join Date: Oct 2013
Location: Bend, Oregon
Posts: 81
Quote:
Originally Posted by Uniblurb View Post
If you went with an aftermarket crank sensor rather than a Mopar one that's most likely your problem. Two brand new aftermarket ones from a local parts store in my 96 4.0 functioned just as erratic as the bad OE one and drove me nuts. Run the below test as a link in my signature using a an ohm-meter set to the lowest ohm setting and you'll probably find your new one tests bad if it's aftermarket.

It's not a good idea to leave the metal shield off the crank sensor since it's there to protect the wiring. I've installed them about 4-5 times and use a little bit of that sticky window rope caulking to hold the bolt/shield/sensor in the socket while installing from the bottom. Also tape your swivel loosely with electrical tape so it doesn't drop down too far. Doubt if the little bit of space between the sensor and trans bell housing, w/o the shield, is going to make a whole lot of difference since the hole is tight enough it seems to hold the sensor itself straight. Good luck!
Thanks for the advice! I will try all of that and look into getting a Mopar sensor if this one continues acting up. Good thinking with the caulking, I actually have some of that stuff.
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Unread 04-02-2014, 08:51 AM   #4
Uniblurb
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1996 ZJ 
 
Join Date: Jan 2012
Location: Central, Ohio
Posts: 3,397
Quote:
Originally Posted by i6zombiejeep View Post
Thanks for the advice! I will try all of that and look into getting a Mopar sensor if this one continues acting up. Good thinking with the caulking, I actually have some of that stuff.
You're welcome and if you pin the cable by the crank sensor to the far left outside with a wire tie or bungee it's easier to get the bolt/metal shield/sensor in. Also disconnect the neg cable on the battery every time you disconnect or connect a sensor.

Make sure all your grounds are good/clean including the one on the fender next to the battery and the 3 on the engine block. There's 1 on the oil dip stick tube bracket and 2 on the coil bracket studs. One of these grounds on the coil studs near the 4.0 motor mount grounds the PCM which in turn grounds all the sensors. This rusted/oily PCM ground on my 96 4.0 took out 2 PCM's and a crank sensor. Learned a harsh lesson on that one.

When purchasing a Mopar crank sensor you can save some $ by buying online rather than the dealer. I don't have the 98 parts list but it looks like your 98 4.0 takes a Mopar 4897321AA according to the below sites.

http://www.amazon.com/Mopar-4897321A...&vehicleType=6

http://www.ebay.com/itm/OEM-CRANKSHA...10d77a&vxp=mtr

There's a lot of real good info in the dirty dozen link in my signature written by ZeeJay. If you haven't done it yet clean the IAC and there's a link on how to do it in his thread. Good luck!
__________________
96 4.0 ZJ Laredo, 2004 4.7L WJ Limited, 93 4.0 XJ (spare), 96 4.0 XJ (son's)

-Stalling ZJ? 12 things to check before replacing a sensor; the Dirty Dozen
-Crankshaft position sensor multimeter test. & video of testing.
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