2.4L Off-Idle Stumble/Hesitation

[cl350rr]

Hi, I have a 2005 Liberty, 2.4L/6sp, 2WD sport, 78,xxxmi. I have been chasing an engine hesitation problem and am hoping to find someone who has delt with it before.

It has not thrown any codes, I have been driving it for about 8,000 miles and it has done this since I got it

symptom, sitting at a stoplight idling fine, when I go to accellerate the engine stumbles until it is over 2000rpm. other than that the engine runs and idles smoothly. if I get below about 1500rpm while driving and try to accellerate, it will buck a few times then smooth out when it gets close to 2000.

I know a 4 cylinder does not like to be at low RPM but this is somewhat dangerous as It takes a second or two for the engine to rev up before I can leave a light. and if the ac is on, it makes the situation worse. if the engine is not above 2000 rpm when I engage the clutch it takes longer for it to smooth out and run correctly.

I have replaced the plugs (factory recommended), air filter, cleaned the map sensor and throttle body, and am about half way through a tank of gas with injector cleaner in it. no affect on the problem.

I would appreciate any advise

 

[seabass1858]

sounds like an injector going out to me

 

[cl350rr]

sounds like an injector going out to me

Thanks. I would think that a failing injector would affect idle as well as the rest of the power band, and probably throw a missfire code. neither is the case.

update: I bought a new TPS this morning to see if that was the problem. before installing I took resistance readings from the new one and the old one side by side. the old sensor shows fixed resistance on between all three posts (three possible pairs) when the sensor input is moved. the new one has varying resistence between 2 pairs when moved which sounds like what it should do.

I installed the new sensor and disconnected the battery for 5 minutes to clear the memory. started it up and it shuttered the first few times i moved the throttle then smoothed out.

test drive, it still hesitates off the line although it seems to be easier to get it to clear up. could be some carbon build up or the computer needs to remap to match the new sensor....

any ideas?

 

[seabass1858]

check resistances across all injectors, I had the same issue with a 3.1mpi chevy, no codes, and ran like crap, checked injectors and found out of tolerance across 1 and I replaced all injectors and problem solved.

 

[Banditsteve]

Hi, I have a 2005 Liberty, 2.4L/6sp, 2WD sport, 78,xxxmi. I have been chasing an engine hesitation problem and am hoping to find someone who has delt with it before.

It has not thrown any codes, I have been driving it for about 8,000 miles and it has done this since I got it

symptom, sitting at a stoplight idling fine, when I go to accellerate the engine stumbles until it is over 2000rpm. other than that the engine runs and idles smoothly. if I get below about 1500rpm while driving and try to accellerate, it will buck a few times then smooth out when it gets close to 2000.

I know a 4 cylinder does not like to be at low RPM but this is somewhat dangerous as It takes a second or two for the engine to rev up before I can leave a light. and if the ac is on, it makes the situation worse. if the engine is not above 2000 rpm when I engage the clutch it takes longer for it to smooth out and run correctly.

I have replaced the plugs (factory recommended), air filter, cleaned the map sensor and throttle body, and am about half way through a tank of gas with injector cleaner in it. no affect on the problem.

I would appreciate any advise

Just been through the exact same problems with my 2.4 (apart from the air filter) Cleaned the throttle body, still the same. Fit new plugs, still the same. Injector cleaner, still the same. Fitted new plug leads and problem disappeared altogether!!!! There was a tiny split in number 3 lead which had been rubbing slightly on something. These are also supposed to be a service item that should be replaced every 48k or somewhere round there. Can't guarantee it will cure your misfire but it is the next cheapest thing on your shopping list! Good luck! Steve :happy160:

 

[cl350rr]

Just been through the exact same problems with my 2.4 (apart from the air filter) Cleaned the throttle body, still the same. Fit new plugs, still the same. Injector cleaner, still the same. Fitted new plug leads and problem disappeared altogether!!!! There was a tiny split in number 3 lead which had been rubbing slightly on something. These are also supposed to be a service item that should be replaced every 48k or somewhere round there. Can't guarantee it will cure your misfire but it is the next cheapest thing on your shopping list! Good luck! Steve :happy160:

thanks Steve, can't hurt to try it. I'll post back with results

Randy

 

[cl350rr]

Well, I think I found the problem...

pulled the #1 plug wire out to change them and oil went everywhere. took a flashlight and looked down in the plug well and the oil was half way up the plug. turns out the spark plug seal in the valve cover gasket is leaking oil into the well and shorting out the plug.

I have been searching for comon known problems that would cause a hesitation in the 2.4l for a month or more and never once came across this until I searched valve cover gasket failure and guess what the primary symptom is... hesitation.

now I just have to figure out how to get the valve cover off this thing.

 

[cl350rr]

3 hours of work and I have new spark plug well seals and a new valve cover gasket. no mater what you read, my 2005 2.4l does not have a 2 piece intake manifold and the whole manifold has to come free from the engine to get the valve cover off.

also if you find yourself preparing to do this job I recommend you get ahold of an 8mm deep well socket and make sure it will fit over the studs on the valve cover. the one I have had too small of through hole and would not work until I chucked it up in the lathe and opened the hole a bit.

the libo drives better now, I can lug in gear at 1500 rpm with it bucking and choking on me.

 

[Banditsteve]

Hi, I have a 2005 Liberty, 2.4L/6sp, 2WD sport, 78,xxxmi. I have been chasing an engine hesitation problem and am hoping to find someone who has delt with it before.

It has not thrown any codes, I have been driving it for about 8,000 miles and it has done this since I got it

symptom, sitting at a stoplight idling fine, when I go to accellerate the engine stumbles until it is over 2000rpm. other than that the engine runs and idles smoothly. if I get below about 1500rpm while driving and try to accellerate, it will buck a few times then smooth out when it gets close to 2000.

I know a 4 cylinder does not like to be at low RPM but this is somewhat dangerous as It takes a second or two for the engine to rev up before I can leave a light. and if the ac is on, it makes the situation worse. if the engine is not above 2000 rpm when I engage the clutch it takes longer for it to smooth out and run correctly.

I have replaced the plugs (factory recommended), air filter, cleaned the map sensor and throttle body, and am about half way through a tank of gas with injector cleaner in it. no affect on the problem.

I would appreciate any advise

Was it not covered in oil when you changed the plugs Randy? I assumed you changed the plugs recently but maybe you changed them a while ago? Regardless, glad you found the cause of the problem. I better keep an eye on mine now then, didn't know about that common problem. I do now though. You learn something every day and thats my learning for the day! Happy Jeeping. Steve :smokin: