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CEL active; P0391 popped up. Changed crankshaft position &

Customer Question
CEL active; P0391 popped...

CEL active; P0391 popped up. Changed crankshaft position & camshaft position sensors with their respective connectors. P0391 keeps popping up.

Mechanic's Assistant: Does the light stay on, or does it blink?

Light Stays on. I lifted the valve cover and examined the wheel on the cam. its tight.

Mechanic's Assistant: What is the make/model/year of your car?

2001 Jeep grand Cherokee limited. 4.7 liter engine

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

Replaced the cam and crank position sensors. replaced the connector to each sensor. checked the cam luctor ring. its tight on the cam gear.

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

Jeep runs 30 miles smooth and thereafter it starts jerking. Hit the throttle and it does respond and take off. It jerks when cruising.

Submitted: 4 months ago.Category: Jeep
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Answered in 2 minutes by:
3/15/2018
Jeep Mechanic: roybelding, ASE Certified Technician replied 4 months ago
roybelding
roybelding, ASE Certified Technician
Category: Jeep
Satisfied Customers: 7,744
Experience: My knowledge of Jeeps from the early 60's till present. Love to help people with there issues.
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hello, my name is ***** ***** I will be glad to assist you. please allow me a couple of minutes to gather some basic info.

Roy

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Jeep Mechanic: roybelding, ASE Certified Technician replied 4 months ago

can you verify the code?? 391 is not showing up

Roy

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Customer reply replied 4 months ago
I thought it was P391. Anyway its regarding the crank position sensor and camshaft position sensor. Its a Jeep 2001 grand Cherokee limited, 4.7 liter engine
Jeep Mechanic: roybelding, ASE Certified Technician replied 4 months ago

ok. I need the exact code number there are several codes for the crank sensor and each one is different. we need that to narrow the area of failure for you.

Roy

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Customer reply replied 4 months ago
P1391 & P0340
Jeep Mechanic: roybelding, ASE Certified Technician replied 4 months ago

ok

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Jeep Mechanic: roybelding, ASE Certified Technician replied 4 months ago

do you have a scan tool??

There are some tests that require a scan tool for the sync check

Roy

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Customer reply replied 4 months ago
I just bought and used the Autel Maxisys P. Right now I have to put the valve cover back on before I can do any testing. Battery has been removed for now..
Jeep Mechanic: roybelding, ASE Certified Technician replied 4 months ago

ok, let me get the tests for you

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Jeep Mechanic: roybelding, ASE Certified Technician replied 4 months ago

ok, below is the description with the possibilities and attached is the flow chart

Roy

SYMPTOM
P1391-INTERMITTENT LOSS OF CMP OR CKP

WHEN MONITORED
Engine running or cranking.

SET CONDITION
When the failure counter reaches 20 for 2 consecutive trips.

POSSIBLE CAUSES
- CMP sensor out of sync
- Damaged tone wheel/flex plate (crankshaft)
- Damaged tone wheel/pulse ring (camshaft)
- Irregular lab scope pattern of CMP signal
- Intermittent CKP signal loss when wiring is wiggled
- Irregular Lab scope pattern of CKP signal
- Wiring harness intermittent
- Intermittent CMP signal loss when wiring is wiggled
- Sensor connector/wiring
- Sensor connector/wiring
- Camshaft position sensor
- CKP sensor connector/wiring
- Crankshaft position sensor

d0281a6b-dbd5-4d0a-9cb5-...JPGd0281a6...JPG4f87f261-92d5-46a2-8d1a-...JPG4f87f26...JPGe946354c-7ae7-403d-9841-...JPGe946354...JPGf8487be2-0e00-438f-a1a5-...JPGf8487be...JPG
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Jeep Mechanic: roybelding, ASE Certified Technician replied 4 months ago

any update

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Customer reply replied 4 months ago
I have not reassemble it yet. As soon as I do Ill reply.
Jeep Mechanic: roybelding, ASE Certified Technician replied 4 months ago

Please take a moment and rate my service 3 stars or better. that is the only way the site will pay me for my efforts.

Roy

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