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I've got a 96 Jeep Cherokee 4.0. I removed the catalytic…

I've got a 96...

I've got a 96 Jeep Cherokee 4.0. I removed the catalytic converter & O2 sensor a year ago. Then one day, iot wouldn't start. Getting codes PO130 and 136--which points to O2 sensor in banks 1 & 2. . Have already replaced crankshaft position sensor, but to no avail. Is there a fix to run this Jeep without a catalytic converter & O2 sensors?

Mechanic's Assistant: Have you located all of the vehicle's oxygen sensors? Are the wires leading to and from each intact and in good shape?

I actually removed an O2 sensor when I cut out the old & rusted catalytic converter.

Mechanic's Assistant: Are you fixing your Cherokee yourself? What have you tried so far?

Yes. Replaced the crankshaft position sensor, cam position sensor and ECM. Still no spark. I read on a forum that the O2 sensors can actually shut down the ECM.

Mechanic's Assistant: Anything else you want the mechanic to know before I connect you?

Just trying to squeeze a few miles out of this rusted Jeep. My area doesn't require emission testings, so I'm just looking for a simple fix.

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1/20/2018
Chris
Chris, Shop Foreman
Category: Jeep
Satisfied Customers: 14,668
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Customer reply replied 4 months ago
Hello Chris. I've been frustrated for a few months with this issue; been reading all the Jeep forum postings on grounding issues, crankshaft position sensor issues, fuses and the sort with this problem. I stumbled on a posting that mentioned that an O2 sensor issue will cause a no-start. This Jeep has 200,000 miles on it, and I'm not interested in replacing the catalytic converter or buying new 02 sensors. Just want to get this thing started. Can you help?
I am a shop foreman at a Jeep dealer and know first hand that disconnected o2 sensors will not kerp the engine from starting. Something else is causing the no spark. Besides the ECM, cam and crank sensors, you may have a failed ignition coil, or ASD relay. A blown fuse for the ASD relay circuit will also cause a no spark, so check those items next.
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Let me know if you find any issues with the items I mentioned.
Chris
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Customer reply replied 4 months ago
Forgot to mention that I bought a new coil, too. Does that narrow the issue to the ASD relay? I must say that a few of my bigger fuses (passenger side, under hood) weren't in the proper places when it WAS running. (I saw a similar mention of that in a post, too.)
Customer reply replied 4 months ago
Is there a way to test the ASD relay with a voltmeter? I did try swapping the fuses around, but to avail.
Possibly, try swapping the ASD relay with another and see if that helps. I will check back with you in about 30 minutes.
Chris
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Tell me, when you turn the key on to the run position, does the relay click on for about 2 seconds and then turn off?

Chris

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Customer reply replied 4 months ago
that's exactly what happens (about two clicks). Looking again at the CPS for issues. Read something about the importance of an "air gap" on the install. Hmmm. Getting the 5 volts along terminals 1 & 3, but seeing a reading on the ohm meter on the middle prong...and thought that should be zero.

Okay When you crank it, does the tachometer move up a little and/or do you get an RPM reading on your scan tool? Also, do you have 12 volts on cavity # 30? (look on the bottom of the relay to see where terminal 30 is)..

Chris

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Customer reply replied 4 months ago
Thanks for your continued patience, Chris. Tachometer doesn’t move during cranking, but I am getting 12 volts across #30. Any further ideas would be greatly appreciated!

Ok, then if the tach does not move when cranking, then that tells me the PCM is not seeing a signal from the cam and/or crank sensor. Does the distributor rotor turn when cranking?

Chrid

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Customer reply replied 4 months ago
Argg: the rotor turns while cranking. Another Internet theory mentions an alarm harness issue in the Grand Cherokees, but mine is a Cherokee Sport (and I don’t have power locks).

Does your scan tool display real time sensor data? if not can you get, rent, borrow one? At this point it would be a huge help.

Chris

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Customer reply replied 4 months ago
I will get one this week! (Thanks again.)

You are welcome! I will keep an eye out for your reply this week.

Chris

Chris
Chris, Shop Foreman
Category: Jeep
Satisfied Customers: 14,668
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Customer reply replied 3 months ago
Chris: I still haven't purchased that "real time" scanner yet (about $100 on Amazon), but was wondering if an analog, mid-1970s Penske auto analyzer that I have might work. I tried a different ECM that I got on eBay, but to no avail. Any ideas on what could be the issue? Thanks.

A scanner from the 70's will not work. It has to be an OBD II scan tool. Maybe you can rent one for now?

Oh thanks for accepting my help so far!

Chris

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Customer reply replied 3 months ago
Chris: I finally broke down and bought the proper scan tool on Amazon. It'll be here later this week.I also ordered another CPS. What I neglected to tell you was that the one I originally installed came with an incorrect connector...so I had to splice it in. With all the wire colors the same (black), I may have shorted the sensor out by guessing at the correct wiring. Wouldn't that be possible if I mixed the 5 volt line with the ground?Anyway, I'm looking forward to working with you to FINALLY get this Jeep started. Thanks again.

Thanks for the update! Yes you may have damaged the sensor, so getting a good fresh one is a good idea. I will be keeping an eye out for you later this week.

Chris

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Customer reply replied 3 months ago
Chris: I hope you haven't lost faith in me: we've been battling major cold (and now snow) in the Chicago area...and the Jeep is parked outside. I did receive the CPS and scan tool, so I'm just waiting for the weather to be a bit more cooperative so we can solve this thing. Thanks!

Sounds good my friend! I totally understand. Get back to me when you can.

Chris

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