Engine Mechanical problem
2002 Jeep Liberty 6 cyl Four Wheel Drive Automatic
I have a Jeep Liberty Sport 2002, 6cyl 4 wheel drive. Recently when driving on a highway I needed to accelerate rapidly andf punched the gas pedal. It immediately started to " buck" and backfire. When I let off of the gas it was vibrating terribly.I managed to get to work and left the car standing all day. When I started it after work it ran fine but the engine light remained on. I was told that if ther is nothing wrong the engine light would shut off eventually. It did it again several days later and I managed to get it to a auto repair shop. They told me it was the fuel pump and that they would change it along with the filter, two sensors, all coils and spark plugs. It now starts fine but will always stall while underway. The mechanics cannot find the problem. HELP! I need this car for work!
It would be helpfull if you have the code written.
The code is more important than anything guessing.
Sorry it's costing you money and still the problem is not solv.
If you take your car to auto part store or get one with us on link below. Write the code down and post it to me.
November, 30, 2009 AT 4:11 PM
That's the biggest problem that I have, all of the codes have cleared and we can't figure out why it is still stalling. It starts fine and runs, however, we take it out for a test ride, and it constantly stalls. As I mentioned before, both fuel pumps were replaced along with the fuel filter, all ignition coils, new plugs and two new sensors, still no luck. We are now lost.I don't know why it is stalling?
Check the firing order, the engine may not start or it may pop and backfire when firing order is messed up.
The replacement wires should also be routed exactly the same as the originals, and supported by looms or clips so they do not contact the exhaust manifold.
You could scan it anyway, there may be pending code.
December, 1, 2009 AT 6:56 PM
I will check the firing order and the wires first thing in the morning.I have my fingers crossed. Thanks
December, 2, 2009 AT 5:31 PM
Timing, firing order ok. Now the mechanic tells me that my computer went crazy.I need a new one. So far they have changed both fuel pumps, all ignition coils and spark plugs, fuel filter, ignition wires, battery and now I need a new computer for upteen dollars.I may not know much about cars but I don't think that I am that stupid either. How can every part that they replaced be bad all at the same time. When I ask them if there are any codes on the diagnostic meter, they claim it is all clear. How can that be? I am frustrated, tired and disgusted and I don't know what to do. Any help will be greatly appreciated. Thanks
December, 3, 2009 AT 1:24 AM
The problem must occur a number of time before the engine code presents itself again since the previous code was clear by your mechanic, its call the drive cycle.
Here is a drive cycle technique to bring back the engine light.
Ensure that the fuel tank is between 1/4 and 3/4 full.
Start cold (below 86 F /30 C) and warm up until engine coolant temperature is at least 160 F (typically requires at least one minute; up to 3 minutes).
Accelerate to 40-55 MPH at 25% throttle and maintain speed for five minutes.
Decelerate without using the brake (coast down) to 20 MPH or less, and then stop the vehicle. Allow the engine to idle for 10 seconds, turn the key off, and wait one minute.
Restart and accelerate to 40-55 MPH at 25% throttle and maintain speed for two minutes.
Decelerate with using the brake by coasting down to 20 MPH or less, then stop the vehicle. Allow the engine to idle for 10 seconds, turn the key off, and wait one minute.
Start the vehicle again; your engine light should come on.
Note: check your receipt when you had your diagnostic test done, because usually they will write down your code number along with the repair information if you still have it
December, 3, 2009 AT 6:35 PM
I will try that procedure tomorrow so that we can check the engine codes.I don't think that I mentioned that the car runs well when it is basically cold. After driving it for ten minutes or so it will stall and then finally shut down. If you let it sit for ten minutes it will start up again until the engine heats up and then it will stall and shut down all over again.
December, 5, 2009 AT 12:47 PM
Well, I did exactly what you recommended, the computer reset itself and guess what, I have a blown intake manifold gasket. They are replacing it now and it looks like this will do the trick.
I appreciate your time and effort and I will recommend this site to everyone. Thanks again!
December, 19, 2009 AT 12:28 PM
My car has been repaired and is running again, however, I have noticed that the car seems sluggish now. It does not have that great pickup that it had before the break down. My question is, if they set the ignition timing improperly, would that affect the pickup?
Thanks again for your help.
December, 19, 2009 AT 5:16 PM
Welcome back to 2carpros. Com
The computer is responsible of advancing and retarding the ignition timing base on the input from Map sensor/baro
When the engine is working hard
(Accelerating), intake vacuum drops as the throttle opens wide. The engine sucks in more air, which requires more fuel to keep the air/fuel ratio in balance. In fact, when the computer reads a heavy load signal from the MAP sensor, it usually makes the fuel mixture go slightly richer than normal so the engine can produce more power. At the same time, the computer will retard (back off) ignition timing slightly to prevent detonation (spark knock) that can damage the engine and hurt performance.
An engine code should be set, keep your eyes on it or you can have the map sensor tested.