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Amedee, Jeep Technician
Category: Jeep
Satisfied Customers: 26088
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

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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.

Hello and welcome!

My name is ***** ***** I can assist you with your question.

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

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 months ago.
Ok, it is stalling again.

Ok, can I get the computer code numbers?

Customer: replied 9 months 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 months ago.
Where is the fuel filter on the Jeep Liberty?

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.

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 months 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?

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

Customer: replied 9 months 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 months ago.
The OBD11 tool indicates a problem with the Engine Speed Input Circuit. What is that?

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.

Hello! It's Amedee from just answer.

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

Let me know!

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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