Sluggishness between KJ years

[n00ben]

Hi guys,

A couple of months I bought a 2007 to get me through the winter. I noticed the car felt a bit sluggish right away but didn't think much of it since it's a heavier vehicle than what I am used to driving.

A few weeks later my brother and I loved it so much that he bought a 2004 for himself. As soon as I drove the car I noticed an immediate difference between throttle response.

My 07 has an electric throttle and it feels sluggish. I was reverse parking the other day and there seems to be a dead zone between the first half inch or so of pedal travel which makes little adjustment maneuvers to be almost impossible. When I let go of the brake the jeep does not move as other automatics usually do, so I have to press the gas until I pass that "dead zone" but then the jeep has too much throttle and if you're trying to inch forwards or backwards it's impossible. The rotors and brakes are in good shape and not seizing.

The 04 is a throttle cable and the lightest touch of gas will make the jeep rev, and when you let go of the brake the jeep moves as usual as opposed to the 07. It feels like a completely different jeep even though they have the same 3.7L engine and drivetrain.

I also bought an 03 for parts and it behaves the same as the 04.

Anyone with a late model KJ that can offer some insight if this is normal behaviour? Is there any adjustment in the electric accelerator pedal to make it more responsive? I also cannot locate the PCV in my 07, in the others it's by the oil filler cap.

Oils are all good, new filters, no MIL. Any help is appreciated

 

[tommudd]

You already have it figured out, I have an 03-04 and 05 in the stable, all are the same as far as throttle response.
That is one reason I will never own an 06-07, lifted enough of them and driven afterwards to know that the throttle response is way off.

 

[lfhoward]

I believe the PCV is somewhere near the drivers side rear of the engine block, since the 07 is the same under the hood as my 08. I have the electronic throttle as well. You could look into a device called a Pedal Commander. It modifies the throttle response and has 4 settings: eco, city, sport, and sport+. I don’t have one, but I saw a guy on YouTube install one on his 4Runner because of similar issues.

 

[jeeptorino68]

At this age you should probably also perform a calibration.
There is a certsin sequence of pedal depressions with the key on engine off to go into the calibration sequence.
Made a huge difference on my 08 grand cherokee with the same fly by wire throttle system.
Tuner helped even further to remove lag

 

[JasonJ]

I hate the electronic throttle on my GMC... my Ford/Mercury is great, wouldn't know it was NOT a cable.

Jeep still does feel the best of all of them though.

 

[kejobe]

Agree with the above. It's the drive by wire. I had a 2014 Maxima and it was the same way.

 

[sota]

At this age you should probably also perform a calibration.
There is a certsin sequence of pedal depressions with the key on engine off to go into the calibration sequence.
Made a huge difference on my 08 grand cherokee with the same fly by wire throttle system.
Tuner helped even further to remove lag

Doesn't make a difference on mine. And believe me, it needs help, especially with a stick shift.

 

[n00ben]

Does the pedal work with a spring or hydraulic? If I could make it lighter it would be easier to drive

 

[kejobe]

There's a spring in it. All it does is hold the pedal up.

It works like a dimmer switch for lights, slide the switch more and the lights get brighter. Press the fuel pedal and the butterfly in the throttlebody opens more creating more rpm's. The input from the pedal is just a suggestion. You press the pedal 50% and it's up to the computer to decide whether or not to open the butterfly the 50% your requesting or not.

And the "tuners" for this problem only make the computer think your pressing the pedal further down than you really are. You press it 50% and the "tuner" tells the computer you're wanting 60% or something.

The dead spot is the time it takes for you wanting input to be considered and sent to the throttlebody butterfly motor to open.

As I mentioned, the Maxima I had, I could repeatedly stomp the fuel pedal to the floor and the rpm's wouldn't budge. If I was to do that with my KJ it would be jerking due to the motor wanting to rev being drive by cable instead of drive by wire.

 

[n00ben]

Making the pedal softer would help making the throttle control more precise traversing from "dead zone" to slight input. Right now the pedal is so heavy (compared with cable) that you have very little sensitivity for slight acceleration.

What about the "releasing the brake pedal and car won't move forward" problem?

 

[Martin Jackson]

Hi, sorry to bring up an old subject matter, but does anyone have a positive resolution for the sluggish response on an 07?
I only use my KJ for dune bashing in the deserts of Dubai, the sluggish response it killing me making up the steep dunes, I have to get a run up ... which is not always possible.

Is pedal commander the only way to fix this?

 

[duderz7]

Have considered the possibility of a brake or two hanging up?

 

[JRB]

Pedal commander type things still won't fix the response time itself, but it does modify how the throttle responds once all the pixies finally communicate with each other, which may help you I can't say for sure.

I bought one off amazon about a year ago for $60 and figured I'd give it a try for that price, I ended up liking mine enough to keep it. It has an eco friendly and two sport modes, each with 9 increments that are adjustable.

 

[Martin Jackson]

Pedal commander type things still won't fix the response time itself, but it does modify how the throttle responds once all the pixies finally communicate with each other, which may help you I can't say for sure.

I bought one off amazon about a year ago for $60 and figured I'd give it a try for that price, I ended up liking mine enough to keep it. It has an eco friendly and two sport modes, each with 9 increments that are adjustable.

Would you have a link for the one you got, or know what brand and model it is?

 

[Martin Jackson]

Have considered the possibility of a brake or two hanging up?

Not thought about that to be honest, I guess I can jack up each corner and spin each wheel to make sure they are not binding
I don't think that is my issue though, as when I put my foot to the floor, there is a pause before the engine starts to accelerate, and even then, it seems to regulate how quickly it increases engine rpm.

 

[duderz7]

Had a similar issue on my 2004 yukon recently, wouldn't inch forward when brake released, turned out I had som sticky brake calipers

 

[JRB]

Would you have a link for the one you got, or know what brand and model it is?

https://www.amazon.com/Throttle-Response-Controller-Electronic-Accelerator/dp/B08RYHBNM4/ref=sr_1_5?crid=3W3ITFU5XKFQ4&keywords=acclope%2B9%2Bdrive%2Bjeep%2Bjk&qid=1656538842&sprefix=acclope%2B9%2Bdrive%2Bjeep%2Bjk%2Caps%2C89&sr=8-5&th=1

It doesn't list the kj as being one of the models it works for, but mine does and yours should, if I had to guess most all the 2007 dodge/chryslers/jeeps it works for use the same drive by pedal harness.

Simple plug and play, although I did have to remove or loosen the gas pedal to get the harness clipped in, you'll laugh when you see the angle it's at.