How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Juan Crespo Your Own Question
Juan Crespo
Juan Crespo, ASE Certified Technician
Category: Jeep
Satisfied Customers: 1526
Experience:  A.S.E. Master Technician, Advanced Level, Emissions - Asian, Domestic, & European
Type Your Jeep Question Here...
Juan Crespo is online now
A new question is answered every 9 seconds

2001 Cherokee. I've been chasing a missfire and shut off at

Customer Question

2001 Cherokee. I've been chasing a missfire and shut off at an idle for weeks. Numerous parts replaced. Coil plugs injectors. Fuel pressure is good. Harnesses checked. I'm lost here.
Submitted: 1 year ago.
Category: Jeep
Customer: replied 1 year ago.
I've also done the ecm. No used parts. All new. Plugs are fuel fowled pink.
Expert:  Juan Crespo replied 1 year ago.

Welcome, my name is***** am a verified expert automobile technician. I, and all others like me are neither employees nor agents of Just Answer. We are independent service providers using the Site to sell our Expert knowledge to customers. I do my best to provide EXCELLENT 5 STAR service, please let me know what you need from me so you’re satisfied with my efforts and reward me with a Positive Rating.

Well, I think we should take whatever information the ECM can give us to help us diagnose this stalling poblem; for example, we know misfires are about the worst thing that can happen, that's why the ECM will flag a corresponding code whenever it sees a misfire. Do you happen to know what that code or codes are?

Customer: replied 1 year ago.
Well before I worked on it in had a 301 303 and maybe one evap code.
Customer: replied 1 year ago.
Now it has none. But I did reset it. But nothing yet. However I have noticed the oil gauge seeming to spike on its own since plugs and wires have changed. It is moody and happens randomly. It stays spiked when it does act up leading me to believe that was electrical.
Customer: replied 1 year ago.
I ment plugs and injectors changed sorry
Expert:  Juan Crespo replied 1 year ago.

Thank you for that extra bit of information. Now, bear with me as I share my thought process on what could be happening; the ECM knows there is a misfire based on signals it gets from the crank sensor that tell it crank speed slowed down as a particular cylinder was firing. So what if the crank sensor was going bad and was no longer providing reliable information to the ECM? Could that be the reason why there are no current misfire codes?

Well, if on top of what I just stated, we add the fact that bad crank sensors are all too common on these vehicles, makes me think that's probably what we're dealing with. Why don't we give a new crank sensor a try and see what happens? Just make sure you get a good new part that comes with a felt or paper spacer and that you follow the install instructions in the box to the letter - no over tightening!

Please let me know how it runs afterwards.

Best Regards.

Customer: replied 1 year ago.
Yeah I hear that. I mean I've seen them come and go needing crank sensors. I've shook the wire a few times to make sure that it wasn't wiring. Do they really act intermittent like that sometimes? Sometimes this truck is great. Sometimes it's horrible and won't pass 5 mph. Sometimes the miss is only at an idle. It's wierd. When it does stall it's more like shutting it off then bogging down or choking.
Customer: replied 1 year ago.
Posted by JustAnswer at customer's request) Hello. I would like to request the following Expert Service(s) from you: Live Phone Call. Let me know if you need more information, or send me the service offer(s) so we can proceed.
Expert:  Juan Crespo replied 1 year ago.

That's certainly what a bad sensor will do. It can drive you crazy because it's the computer's only source for those signals since there's no other sensor to compare crank speed or position.

Customer: replied 1 year ago.
Ok. I'll give it a go and let you know
Expert:  Juan Crespo replied 1 year ago.

Well, all I can say at this point is that I'm rooting for you. Go for it!

Customer: replied 1 year ago.
Juan...sorry I have been busy and haven't had time to post back. Crank sensor replaced with Mopar brand from dealer. No change. Took out champion platinum plugs which were still perfectly gapped and replaced with ngk. Probably 70% better. Dies at an idle still and it's very moody. Some days I can't sit at any lights. Some days I can sit at all of them. I know from this it's not mechanical and definately electrical. I shook all the harnesses to try and simulate a bad connection. Nothing. Only codes are the p0301 and p0303. That's it. Coil is new..but aftermarket. So I've ruled it out so far. But I'm running out of options here.
Expert:  Juan Crespo replied 1 year ago.

Is there any chance of you borrowing a scan tool capable of reading engine data so we can look at all the engine parameter id's when the engine is getting ready to stall? I mean, other than that, I'm just about out of options.

Customer: replied 1 year ago.
I'm going to ask my buddy tomorrow to borrow one. I'll get back to you
Expert:  Juan Crespo replied 1 year ago.

Please let me know.