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Amedee, Jeep Technician
Category: Jeep
Satisfied Customers: 24145
Experience:  ASE certified Technician advanced level specialist. Wisconsin certified emissions state inspector
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My 2002 Jeep Liberty 4.0 is surging under throttle and self

Customer Question

My 2002 Jeep Liberty 4.0 is surging under throttle and self limiting the r.p.m. I can put my foot on the floor and it revs up and then limits at 2,100 and drops, then surges up to 2.100 and drops again. Stalling under load.
JA: Is the check engine light on? Does the car stall at idle or when driving?
Customer: The check engine light is on.
JA: Are you fixing your Liberty yourself? What have you tried so far?
Customer: Yes, I hope so. I have checked vacuum lines and that is about it.
JA: Anything else you want the mechanic to know before I connect you?
Customer: I think that is all. I have a OBI diagnostic unit that I could put on it.
Submitted: 9 days ago.
Category: Jeep
Expert:  Amedee replied 9 days ago.

Hello and welcome!

My name isCustomerand I can assist you with your question.

Expert:  Amedee replied 9 days ago.

Are you looking for possible causes or would you like me to walk you through this diagnoses?

Can I start by getting any stored codes in the computer?

Customer: replied 9 days ago.
Engine Speed Input Circuit and evaporative tank leak
Customer: replied 9 days ago.
My phone isn't handy. The problem has corrected itself for the moment.
Not sure what to say about that.
Expert:  Amedee replied 9 days ago.

Well, I can still help and give you some possible causes if you would like and if you are still willing to pay for my service.

Customer: replied 9 days ago.
Ok, it is stalling again.
Expert:  Amedee replied 9 days ago.

Ok, can I get the computer code numbers?

Customer: replied 9 days ago.
It seems like it is out of fuel. But gauge says 1/3 full and that should be about right. Where is the fuel filter on these vehicles?
Customer: replied 9 days ago.
Where is the fuel filter on the Jeep Liberty?
Expert:  Amedee replied 9 days ago.

The problem could be low fuel pressure due to a bad fuel pump or restricted fuel filter. The fuel filter is located back by the fuel tank.

Another possible cause is a bad camshaft position sensor or crankshaft position sensor provided the engine is in time (timing chains have not stretched or jump time). The camshaft and crankshaft position sensor go bad very often on these vehicles causing this sort of issue.

Last but not least would be a plugged exhaust system.

Expert:  Amedee replied 9 days ago.

I am glad I can help!

It has been a pleasure working with you. Please dont forget to honor your good faith deposit by rating my answer as "5 STAR SERVICE" for assisting you today.

Keep in mind, we can still continue this conversation at no further cost to you even after you rate my answer. Just reply back to me using this page and I will get it and get back to you ASAP!

Please let me know if you have any further questions.

Customer: replied 9 days ago.
The engine started and ran fine after sitting for 20 minutes. It ran for five minutes just fine and then the problems started again. If it was a cam or crank sensor or another issue related to the timing would it run normally again for five minutes?
Expert:  Amedee replied 9 days ago.

YES, the cam and crank sensors can go bad intermittantly causing this sort of issue. It is VERY common.

Customer: replied 9 days ago.
How can I tell if it is the $150 fuel filter, other than by replacing it. Or if it is the cam or crank sensors?
Customer: replied 9 days ago.
The OBD11 tool indicates a problem with the Engine Speed Input Circuit. What is that?
Expert:  Amedee replied 9 days ago.

The engine speed circuit is the crankshaft or camshaft position sensor. These sensors are used by the computer to tell where the cam and crank are in their rotation so that the computer can fire spark and fuel. If you get the code for me, I will tell you which one this code is referring too. However, I would recommend to replace them both at the same time anyway because of their high failure rate.

The only way to check to see if the fuel pressure is low due to a bad fuel pump or a restricted fuel filter is to watch the fuel pressure using a fuel pressure tester hooked up to the fuel rail.

Expert:  Amedee replied 8 days ago.

Hello! It'sCustomerfrom just answer.

I am just checking in to see if you need any further assistance?

Let me know!

Expert:  Amedee replied 6 days ago.

Good afternoon.

I see you have viewed my last reply but have not responded back. I am just checking in to see if you have any further questions or to see if you still need help with anything? If so, please let me know as I will be happy to help. If I have answered all of your questions, please dont forget to honor the good faith rating system to complete this conversation.

Thank you and have a great weekend!

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