3.7 L, performance degraded on lower rpms. - JeepForum.com
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Unread 05-13-2015, 01:09 PM   #1
GMV93
Registered User
2009 WK 
 
Join Date: Oct 2010
Location: Ankara
Posts: 62
3.7 L, performance degraded on lower rpms.

Dear friends, i have been driving this KJ for 2 years and now it is given to my wife. I bought a WK CRD, and been driving for some time.

My question is related to KJ 3.7 it has bifuel setup, runs on propane and gasoline. My problem is not related to the fuel i choose to use.

When cruising at very low speeds, such as 20 mph, and wanted to accelerate fast, to pass a truck for example, when i floor it, it kicks down reluctantly,car acts sluggish for few seconds (compared to what i remember.) It accelerates, but slower than expected, it reaches to approx 4000 rpms, and starts to accelerate faster than it happens on lower rpm. feeling is like a huge(until 3900 rpm) turbo lagon a modified small turbo diesel engine. when reaced to 3900- 4100 rpm, it feels like somebody starts to push it from back

it feels like car is lack of fuel at higher rpms, but it is not, i know this because bifuel setup uses seperate injectors with seperate fuel tanks due to having LPG tank. i can switch tp LPG an symptom is same.

this is not a general loss of power problem. car is on 80k miles. no idling problems, no grinding noises, no shifting problems during normal driving conditions. no check engine light. ( what i know as a weird thing is, car vibrates for 1 second on hills, climbing on reverse gear while parking infront of our house ,actually i read it is common on this transmission)

can this be related to torque converter locking mechanism(thinking the reverse gear)? do you know when does torque converter lock?

any first hand experience? it would be highly appreciated to have reply from you.

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Unread 05-14-2015, 01:15 AM   #2
GMV93
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2009 WK 
 
Join Date: Oct 2010
Location: Ankara
Posts: 62
this morning everything is normal. it accelerates as i remember. from standing still or rolling. no problems. variables changed are outside temperature (lower) engine oil temperature together with transmission oil temperature. any ideas?

also i tried Kj on a slope few hours ago, i tried to climb with a constant gas pedal position, it cant decide to down shift or up shift, but holds the speed.
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Unread 05-14-2015, 07:21 PM   #3
WheelinKJ
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2003 KJ Liberty 
 
Join Date: Aug 2013
Location: Dartmouth, Nova Scotia
Posts: 106
Have you checked your tire pressure? I don't know what size tires you have but my 245/75/16's will cause my jeep to be sluggish and heavy if even one is low by as little as 5 psi.

It's likely not that but a very simple thing to rule out
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Unread 05-15-2015, 08:49 AM   #4
GMV93
Registered User
2009 WK 
 
Join Date: Oct 2010
Location: Ankara
Posts: 62
tires are ok. they are stock size. there is a varible which effects the low rpm performance. it changes right after engine increases its speed to approx 4000 rpm. there should be a source for this problem. but it seems nobody has a clue on that. i am on my own again
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Unread 05-16-2015, 06:43 AM   #5
mjuenem
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2005 KJ Liberty 
 
Join Date: Sep 2014
Location: Mahopac, NY
Posts: 219
I just changed my plugs because of an intermittent miss under load and unexpectedly it seems to have gained 30hp. Very happy. Prolly worth a try if you haven't since you noticed this problem.
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Unread 05-26-2015, 01:17 AM   #6
GMV93
Registered User
2009 WK 
 
Join Date: Oct 2010
Location: Ankara
Posts: 62
my spark plugs are not old. but i will replace them to get rid of this variable. I started to feel intermittent low rpm problems during idling. exact symptoms i faced when my TPS gone bad two years ago! I checked TPS percentage when it is full throttle. it shows 108% open which is impossible.
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Unread 05-26-2015, 01:50 AM   #7
xrunndonex
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1994 ZJ 
 
Join Date: Dec 2012
Location: coffeyville, Kansas
Posts: 2,097
Quote:
Originally Posted by GMV93 View Post
my spark plugs are not old. but i will replace them to get rid of this variable. I started to feel intermittent low rpm problems during idling. exact symptoms i faced when my TPS gone bad two years ago! I checked TPS percentage when it is full throttle. it shows 108% open which is impossible.
I'd say your tps **** the bed if it thinks its 108% open
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