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 Jack Your Own Question
Jack
Jack, ASE Certified Technician
Category: Jeep
Satisfied Customers: 42
Experience:  Chrysler Master Certified
77854973
Type Your Jeep Question Here...
Jack is online now
A new question is answered every 9 seconds

Trying to find out what's wrong with my jeep

Customer Question

Trying to find out what's wrong with my jeep
Submitted: 1 year ago.
Category: Jeep
Expert:  AZTechBrian replied 1 year ago.

What is it doing?

Customer: replied 1 year ago.
Missing while idling and driving while warming up for about 30 seconds it will go into a really rough idle and cut off. I've replaced spark plugs, spark plugs, csp, and everything I can think
Expert:  AZTechBrian replied 1 year ago.

It misses at idle. Ok.

If you bring the RPM up, does it continue to misfire? or does it smooth out?

Customer: replied 1 year ago.
Smooth out
Customer: replied 1 year ago.
It misses while I'm driving up hills especially
Expert:  AZTechBrian replied 1 year ago.

Ok. Do you have access to a vacuum pump, like a mity vac? Are there any stored trouble codes? is it a 4 or 6 cylinder?

Customer: replied 1 year ago.
No I don't. I just changed the coil pack like 30 minutes ago and there was a check engine light before I disconnected the battery
Customer: replied 1 year ago.
4.0
Expert:  AZTechBrian replied 1 year ago.

Ok. I really need to know what the code is in order to have a better idea of what is happening here. I suspect the code will appear again very soon, if it's not already there as a pending code. Can you check for pending codes?

Customer: replied 1 year ago.
as of right now there is no codes
Expert:  AZTechBrian replied 1 year ago.

Not even pending? Pending codes wont light up the CEL. Did you happen to check it before you disconnected the battery?

Customer: replied 1 year ago.
The codes I had was loss or intermittent signal from ckp or csp. I also had a code from the coil pack and misfires before I changed the spark plugs
Customer: replied 1 year ago.
The code reader has a yellow light on it but there is no stored codes
Expert:  AZTechBrian replied 1 year ago.

It probably has pending codes in it. They will mature soon.

It had both cam and crank sensor codes before?

Customer: replied 1 year ago.
Intermittent signals yes.
Expert:  AZTechBrian replied 1 year ago.

Do you recall the code number?

Have you inspected the crankshaft sensor connector well? crank sensors are not uncommon failures on those jeeps.

Customer: replied 1 year ago.
Maybe 303 and 302 not real sure
Customer: replied 1 year ago.
It looks like it's not plugged in all the way but the jeep won't run if it's not plugged all the way in right?
Expert:  AZTechBrian replied 1 year ago.

It shouldn't, but it may be making contact, just not very good contact. Try plugging it in good and see what we get

Customer: replied 1 year ago.
Same thing
Expert:  AZTechBrian replied 1 year ago.

Ok. Without a code, there are too many possibilities as to why it could be giving you these symptoms. Did you say that your scan tool indicated that there was a code, but would not display it yet?

Customer: replied 1 year ago.
It has 3 status lights green yellow red and it's yellow when I plug it in and try to pull codes.
Expert:  AZTechBrian replied 1 year ago.

Ok. I assume that yellow means that there are pending fault codes and red means there are current fault codes. It will not allow you to review pending fault codes?

Customer: replied 1 year ago.
No it wont
Expert:  AZTechBrian replied 1 year ago.

how long ago did you disconnect the battery and clear the codes? I am wondering if you drive it around the block if it will give us the code so we can proceed with troubleshooting this issue

Customer: replied 1 year ago.
When I changed the coil pack. I just drove it around the block and no CEL or codes
Expert:  AZTechBrian replied 1 year ago.

it may take a couple drive cycles to display the code. It is definitely seeing a problem which i assume is why the light is yellow. Unless the yellow light indicates that the monitors have not run. I am not familiar with your scan tool. I have to get going for the day, so if you want I can opt out so somebody else can help you, or you can try to get the code to display and we can proceed tomorrow. it's totally up to you.

Customer: replied 1 year ago.
Ok thanks for your help
Expert:  Jack replied 1 year ago.

Hello and thanks for your guestion.. I will do my best to give you sound advice based on the information you provide. like it was stated before a code would be very helpful in this situation to help rule possible issues. on these 4 liter engines I have seen plenty of these kind of issues caused my the PCM. this is just based off of what I have read so far. check over the PCM and check for any corrosion along the seams mainly at the bottom. also check yout 5 volt refference at the cam and crank sensor (if you can). I would also recommend to drive it and hopefully the code will set again.

Customer: replied 1 year ago.
The code I'm getting p1391
Expert:  Jack replied 1 year ago.

Check the cam sensor for correct index, check cam sensor adapter assembly for a seized or binding can sensor shaft. Inspect the can position sensor drive gear for damage. If the cam position sensor drive gear is damaged, remove the oil pan and oil pump, inspect the camshaft drive gear for damage as well.

Customer: replied 1 year ago.
How do I check for correct index?

Related Jeep Questions