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-   -   Loss of Acceleration on 2004 4.0 6Cynlder JEep (http://www.jeepgarage.org/f203/loss-of-acceleration-on-2004-4-0-6cynlder-jeep-34422.html)

NovaKitFox 01-20-2012 07:06 PM

Loss of Acceleration on 2004 4.0 6Cynlder JEep
 
Hello, New member, Newer jeep owner, Have had my 2004 WJ for almost a year now.

Found this sight well Searching for others that might know what my issue is.

My Jeep has a Loss off Acceleration/ LAck of it.

From a dead stop it starts to Accelerate fine then about 3k rpm it losses the Rate of where if Incresses speed to almost nothing.

If i keep the pedal pressed no more than 1/4 down then it accelerates better.
If i stomp it or more than that, Engine Revs up, and minmal power seems to get to the wheels.

At Highway speeds. It's just as bad. when needing to pickup speed, lets say form 60 mph. A 1/4 press it will start to accelerate slowly. any more or to the point where it needs to downshift to accelerate faster it gains speed even slower.

Transmission will downshift, Engine will Rev up and Speed will not be gained while revving at 3-4 k rpm
-------
What i have done so far
I have (with the help of my Jeepspert as i call him) I have REplaced the TPS, Cleaned the Throttle intake (i think it's called that) in and out. Replaced Sparkplugs..

Issue Reimained. After a day with this it seems the IAC went out and i gained a 500-1k extra RPMS. and engine would stall out when slowing down due to Transmission not Shifting down. Took it to the Dealer and they replaced the TPS and IAC and every thing worked fine for 3 days.


I just got a New Air intake put on, it ran great last night and this morning I had The same issue with for Acceleration rear it's ugly head again.. And i got the code P0135 posting on my jeep. I'm Pretty much going to end up taking it to the Dealer again, but was Hopeing for any insight into this issues from Fellow Jeep Owners.

Thanks to any one who can help in advance
(and sorry for the long post, and any typos lol)

cheapjeep 01-20-2012 07:32 PM

Re: Loss of Acceleration on 2004 4.0 6Cynlder JEep
 
That code is for the bank #1 (Before cat)O2 sensor and could very well be causing your problem. It definitely needs changed as it is saying the heater has failed.This sensor tells the ecm what fuel mixture is needed.

Frango100 01-20-2012 09:20 PM

Re: Loss of Acceleration on 2004 4.0 6Cynlder JEep
 
X2 on that.
The oxygen sensor should reach a temperature of 500-600° C before it can do its job. For that reason there is a heater element in the sensor. If this heater doesn´t work, then the fuel control system will not use the oxygen sensor signal and operates with a preprogrammed fuel schedule.
I´m only not sure though if this sensor failure would make any difference during acceleration, because the fuel control system will not use the oxygen sensor signal in that case.
You could maybe also measure the fuel pressure at the fuel rail, because with a too low pressure, you also get problems with acceleration. Or you simply change the fuel filter/pressure regulator (1 unit just in front of the rear axle). It also could be the fuel pump.

2005JGC 01-21-2012 01:17 PM

Re: Loss of Acceleration on 2004 4.0 6Cynlder JEep
 
High rpm lack of power could be a plugged exhaust (broken, failed catalyst), and intermittant good operation can be because the obstruction moves around and sometimes its not as big of a problem as others. This would explain decent low throttle operation as its not requiring alot of exhaust flow, meanwhile high rpm need alot of flow.

xTimmy05x 10-24-2012 12:16 AM

Re: Loss of Acceleration on 2004 4.0 6Cynlder JEep
 
I too am running into this same problem. i have an 04 Rocky Mountain, with a 4.0L with just over 150,000 miles now.

I was advised by a friend to unplug the O2 sensors and remove them to free up exhaust flow out of the engine but this didnt help. would it?

I have replaced both the MAP and TPS sensors as well as the IAT sensor. Ive been told that a crack in the intake manifold might cause this as well. and i do have to admit. my radiator fan is out.... the motor is shot on it. so it has been over heating when not moving, which i know the heat can cause the manifold to crack. =\

My engine as well makes a very odd lower pitch sound when I try to acclerate hard, its almost a groaning sound, and there is a very load ticking from the top of the motor when the engine is turned off for about 5-10 seconds. (exhaust backing up into the engine from a clogged cat or muffler?)

thanks for the help guys

stashgto 10-24-2012 12:39 AM

Re: Loss of Acceleration on 2004 4.0 6Cynlder JEep
 
Anyone know your fuel pressure, and -or are you having any fuel gauge issues? Does the issue change if going uphill?

xTimmy05x 10-24-2012 12:31 PM

Re: Loss of Acceleration on 2004 4.0 6Cynlder JEep
 
Ive driven both on flat ground and up hill. its issue happens in both cases. but i did first encounter the problem going up a steep hil

xTimmy05x 11-01-2012 08:56 PM

Re: Loss of Acceleration on 2004 4.0 6Cynlder JEep
 
Ive also now heard that this may be the torque converter? anyone know if that maybe true?

Frango100 11-01-2012 10:57 PM

Re: Loss of Acceleration on 2004 4.0 6Cynlder JEep
 
Would not expect the torque converter, because then the rpm would go skyhigh with no or little acceleration. If the rpm stays stable when pressing the accelerator, it should be more engine related.


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