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Unread 08-19-2009, 03:15 PM   #1
Crit
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1997 ZJ 
 
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Wife's ZJ has had full tune-up / overhaul, still throws code 43

I've got an intermittent problem with my wife's ZJ. It's a 97 4.0 Auto 2WD. Plugs, wires, cap and rotor were changed about a year ago and look great. Two months ago, it got the following:


Brakes bled, turned, new pads, new shoes.
Removed and cleaned throttle body.
Injectors sent off to be cleaned and flowed - now within .5% of one another.
New fuel pump/screen/filter/accumulator telescoping bastard assembly.
New coil.
New cat and reworked the exhaust (straightening, rust removal).

It stalled on her today, for the first time in 2 months. It dropped from freeway speed to 30mph, then slowly recovered. Misfires, bucking, etc. seemed to be the symptom.

Historically, it seems to store code 43, and I've never gotten it to go away, even after all that work. Of course, it never misfired on me so I was hoping I had gotten away with the fix. Before she leaves today, she'll pull the code again but I fully expect it to be code 43. Code 43 reads:

Peak primary coil current not achieved with max dwell time
OR
Cylinder misfire
OR
Problem in power module to logic module interface

With the economy the way it is, I wanted to show the ZJ a little love and keep the wife in it a little longer. It's not bad on gas or insurance, and it's PAID OFF. Alternatively, can someone tell me where the power module and logic modules are? It almost reads like I could have a bad connection between them.

Please help me troubleshoot this thing before she starts shopping for a new car.

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Unread 08-19-2009, 07:32 PM   #2
ratmonkey
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a 1997 should be giving you p-codes in the odometer when you use the key turn trick. those are obdi codes and do not apply to a 97.

a p0043 would be a shorted o2 sensor.
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Unread 08-19-2009, 09:08 PM   #3
Crit
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Crap, then it's not a 97. 95, perhaps. It definitely isn't OBD2.
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Unread 08-20-2009, 07:59 AM   #4
Crit
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Correction - the ZJ is in fact a 97. The odometer spits out codes 12, 21, 43 and 55. When Autozone scanned the OBDII codes, it came back with upstream O2 (bank 1 sensor 1) and multiple misfires. I'm not worried about the O2, as bad as the car runs. The O2 sensor could have been telling the truth, and the mixture's just that screwed up.

I'm leaning toward blaming the crank sensor. I drove the Jeep last night and it finally died while I was behind the wheel. As much as it sputters and bucks, the tach jumps all over the place. I'm thinking that a crank position sensor that's losing counts would account for everything I've seen, as it'll run super-lean, thinking that the engine is suddenly running slower than it is.

Is the crank position sensor easy to change? I picked up the part and it looks simple enough, but I'm not sure how to access the current one.

By the way, am I the only one that thinks it's ridiculous that the dealer wants $110 for the same sensor that Autozone sells for $28? Good luck with that, Chrysler.

Last edited by Crit; 08-20-2009 at 12:05 PM..
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Unread 08-30-2009, 09:29 PM   #5
Crit
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I replaced the CKP, and the ZJ made it about a week before crapping out again. What's the next-likely offender? I'm thinking Cam Position in the distributor...
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Unread 08-30-2009, 11:27 PM   #6
ratmonkey
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Jeeps don't like non mopar sensors. Could easily still be the ckmp but could also be rhe cam sensor.
.go mooar though. Same with o2 sensors.
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Unread 08-31-2009, 12:08 AM   #7
MN_NATV
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A bad O2 sensor will make it misfire and generally run like crap, due to an incorrect air/fuel mixture. The O2 sensor will tell the ECM that the amount of oxygen in the exhaust is at one level when its at another level.
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