Need some help with sputtering and misfiring issue

ShannonJ8988

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Joined
Jan 14, 2020
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4
Location
SC
First off im new here so any advice would help out greatly. I have a 2001 TJ 4.0. A few months ago i was driving home from work and the jeep started sputtering and back firing the code came up for missed firing and so i replaced the plugs and coil pack. After i completed the job took the jeep out to see if that fixed my problem but it did not. Jeep started throwing new codes for cam shaft sensor and crank shaft sensor so i replaced both of those. Now jeep runs and idles fine no issues when on flat ground. When i start to go up hills jeep starts sputtering wont go over 2k rpm and will stall out. And the only code it gives is the P1391. Is it possible i need a new timing chain? Any help on this matter will be greatly appreciated. Thank you and sorry this is so long.
 

Chris

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Sep 28, 2015
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What kind of spark plugs did you replace them with? What were they gapped to?

What brand of replacement coil pack and sensors did you replace?

The timing chain is very, very unlikely.

P1391 is a faulty camshaft or crankshaft position sensor.

This video might be worth watching:


Here's two threads worth reading as well:
Jeep TJ Wrangler Crankshaft Position Sensor Replacement
Jeep Wrangler TJ Camshaft Position Sensor Replacement

Should be easy and straight forward. Go with OE Mopar replacement sensors, as aftermarket ones are known to cause issues (no joke).

There is a also procedure in the FSM to test each sensor to see which one is the culprit.

If you don't yet have a FSM, you can download them here for free:
Jeep Wrangler TJ Factory Service Manuals (FSM) & Technical Documentation
 
OP
ShannonJ8988

ShannonJ8988

New Member
Joined
Jan 14, 2020
Messages
4
Location
SC
What kind of spark plugs did you replace them with? What were they gapped to?

What brand of replacement coil pack and sensors did you replace?

The timing chain is very, very unlikely.

P1391 is a faulty camshaft or crankshaft position sensor.

This video might be worth watching:


Here's two threads worth reading as well:
Jeep TJ Wrangler Crankshaft Position Sensor Replacement
Jeep Wrangler TJ Camshaft Position Sensor Replacement

Should be easy and straight forward. Go with OE Mopar replacement sensors, as aftermarket ones are known to cause issues (no joke).

There is a also procedure in the FSM to test each sensor to see which one is the culprit.

If you don't yet have a FSM, you can download them here for free:
Jeep Wrangler TJ Factory Service Manuals (FSM) & Technical Documentation
I replaced the spark plugs with ngks gaped at 0.04. Not sure what brand the coil pack is i just picked one up at advanced auto. The two sensors are BWD. I did watch that video but it differs because that video is for a 4cyl and i have a 6cyl. I will read the links though thank you for your input.
 

Jerry Bransford

TJ Guru
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Nov 9, 2015
Messages
13,006
Location
Escondido California
No not at all
That it runs well when cold is a great clue you likely have a bad O2 sensor. The computer ignores the O2 sensors when the engine is cold and only starts using them to set the air/fuel mixture once the engine has started to get warm. If you replace them make sure to ONLY install NGK or NTK brand O2 sensors. Don't let an auto parts store talk you into Bosch O2 sensors which will only cause problems.
 
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ShannonJ8988

ShannonJ8988

New Member
Joined
Jan 14, 2020
Messages
4
Location
SC
Thank you guys for your input i think i solved the problem when i replaced the cam sensor i didnt replace the whole unit i just replaced the top of it looked at it last night and it had metal shavings all attached to the magnet so i replaced the wole piece and not just the ssnsor and it seems to be running good now thank you