2005 Grand Cherokee Accelerating On Its Own Problem - JeepForum.com
 
LinkBack Thread Tools
post #1 of 8 Old 06-29-2021, 06:12 PM Thread Starter
DM2
Registered User
 
Join Date: Aug 2015
Posts: 4
2005 Grand Cherokee Accelerating On Its Own Problem

I am encountering an issue with a 2005 Jeep Grand Cherokee equipped with the 5.7 liter Hemi V8 where if a driver takes his foot off the brake at a standstill the Grand Cherokee wants to accelerate on its own. The brake pedal has to be pressed hard to keep it from moving at a standstill. I replaced a faulty throttle body with a new Mopar unit about a year ago. The problem just started recently, does anybody know what is causing this issue? Is this issue related to the throttle body? I recently heard if you replace the throttle body without flashing/updating the onboard computer that strange throttle related issues can occur later. Or is something else causing this issue? Thanks in advance for your help with this.

........

DM2 is offline  
Sponsored Links
Advertisement
 
post #2 of 8 Old 06-29-2021, 06:52 PM
Vertisce21
Registered User
 
Join Date: Mar 2020
Posts: 195
Sounds like the sensor for the accellerator is bad. If you did recently replace the throttle body though, that could also be the problem.
Vertisce21 is offline  
post #3 of 8 Old 06-30-2021, 06:38 AM
90grandoneer
90grandoneer
 
90grandoneer's Avatar
2006 WK 
 
Join Date: Apr 2008
Location: City of Trees
Posts: 4,233
When you install a new throttle body, you should do a relearn so it can synchronize itself with the PCM. It's not likely that this is NOW your problem though, as you've had the new TB on for about a year, and probably would have had issues immediately after the install.

IMO, the very first thing you should do is put an advanced diagnostic scanner on the vehicle and see if there are any Diagnostic Trouble Codes (DTC) showing. With it, you may also want to check both live and freeze frame data to see what is going on. What is your fully warmed up idle speed, both in and out of gear? Any other recent work been done to the vehicle? Have you checked for vacuum leaks?

06 GCO, Dk Khaki, QDII, Flshing Hi 3rd Bk Lt, MDS "ON" Lt, Airtab Vortex Gens, Debadged, Fumoto Drain Valve, BT Catch Can, Chopped EGR Tube, SRT8 CAI, AFE Air Filter, 6spd 545RFE, Sonnax Trans Line Press Booster, SC Tuner W/Adv Trans Tune App, DS and HP tuners, Transgo Shift Kit, ARH Long Tube Hdrs w/3 in Magnaflow/Xlerator AP Exh Sys, Bilsteins, SRT Springs/Sways, Cust Eng Cvr, SRT8 frt/rear bumpers, FRI Sidewinder Cam w/6* advance/6.1 valvetrain, SLP 25% UD Pulley, BBK true 90mm T-Body, SOS Ign Coils w/.060 spark plug gaps, TEA ported/milled heads w/new valve seats, SRT Reps with 265/45&295/40X20's. Also 05 Hemi LX modded exactly like WK and Comp Cammed 06 300CSRT8 soon to be replaced by 2021 Tesla Model S Plaid with 1020 hp and 1050 lb. ft. of torque.
90grandoneer is offline  
 
post #4 of 8 Old 07-01-2021, 07:18 AM
Mainsail
Registered User
2005 WK 
 
Join Date: Mar 2010
Location: Puget Sound
Posts: 1,119
Have you put a code scanner on it?

Possibilities:
- Transmission fluid low (causes pressure drops) or much too high (causes fluid foaming and overheating)
- Torque Converter Clutch dragging (would do it more in hot weather)
- Torque converter or torque converter pump failing
- Trans filter drain-back valve failing (causes drain-back and an air bubble)
- Idle speed sensor

Are you noticing any shifting issues, like it doesn't seem to shift to the next gear normally?
How many miles are on the transmission filters?
When was the last time you checked the trans fluid level?

One quick check you can do is after the jeep has been sitting overnight (or longer) start it, immediately throw it into gear and try to pull away (accelerate). Does the trans act like it's asleep and needs to wake up- like it slowly oozes into gear. If it does, then the problem is likely a filter drain-back issue and you're getting air pockets in the TC. These should go away as you drive though, so if your surging is happening any time, and well after you've been driving a while, then maybe that's not the issue.

If you've recently changed the transmission filters, the spin-on one might have been installed wrong. The new seal might have gotten jacked or the old one might have been left in (two seals). It's been a while since I changed mine, but I recall some drama in the directions about making sure the seal was put in correctly.

Poor grammar is something up with which I shall not put.
Mainsail is offline  
post #5 of 8 Old 07-01-2021, 03:41 PM
90grandoneer
90grandoneer
 
90grandoneer's Avatar
2006 WK 
 
Join Date: Apr 2008
Location: City of Trees
Posts: 4,233
Not to hi-jack this thread but, Mainsail, how are you doing in the heat up there. Over here in Southwestern Idaho it's not quite as bad......yet......so far only 104-105*.

06 GCO, Dk Khaki, QDII, Flshing Hi 3rd Bk Lt, MDS "ON" Lt, Airtab Vortex Gens, Debadged, Fumoto Drain Valve, BT Catch Can, Chopped EGR Tube, SRT8 CAI, AFE Air Filter, 6spd 545RFE, Sonnax Trans Line Press Booster, SC Tuner W/Adv Trans Tune App, DS and HP tuners, Transgo Shift Kit, ARH Long Tube Hdrs w/3 in Magnaflow/Xlerator AP Exh Sys, Bilsteins, SRT Springs/Sways, Cust Eng Cvr, SRT8 frt/rear bumpers, FRI Sidewinder Cam w/6* advance/6.1 valvetrain, SLP 25% UD Pulley, BBK true 90mm T-Body, SOS Ign Coils w/.060 spark plug gaps, TEA ported/milled heads w/new valve seats, SRT Reps with 265/45&295/40X20's. Also 05 Hemi LX modded exactly like WK and Comp Cammed 06 300CSRT8 soon to be replaced by 2021 Tesla Model S Plaid with 1020 hp and 1050 lb. ft. of torque.
90grandoneer is offline  
post #6 of 8 Old 07-01-2021, 03:48 PM
Mainsail
Registered User
2005 WK 
 
Join Date: Mar 2010
Location: Puget Sound
Posts: 1,119
Quote:
Originally Posted by 90grandoneer View Post
Not to hi-jack this thread but, Mainsail, how are you doing in the heat up there. Over here in Southwestern Idaho it's not quite as bad......yet......so far only 104-105*.
The pic shows monday. I stepped out of work and it felt like I was back in Saudi.

Sunday was a little bad
Monday was really bad
Tuesday was a little bad
Wednesday was fine
Thursday some people were back in their sweatshirts

We don't have AC, but we do have a whole-house-fan that we run at night. That brings the inside of the house down to 65 or so. Once the sun clears the treeline, wife closes up the windows, shades, and curtains. The cool stays in all day. Monday and Tuesday was rough because it didn't get too cool at night, and Monday's heat had soaked into the walls and structure. So it was a few days of less-than-ideal, but I've flown missions to some hot places, and neither one of us is fragile.
Attached Thumbnails
111.jpg  

Poor grammar is something up with which I shall not put.
Mainsail is offline  
post #7 of 8 Old 07-01-2021, 06:45 PM
90grandoneer
90grandoneer
 
90grandoneer's Avatar
2006 WK 
 
Join Date: Apr 2008
Location: City of Trees
Posts: 4,233
I am sure a lot of folks up in the Northwest are really suffering, because so many don't have A/C. Down here, most have it and our 104-105's aren't usually that bad, as the humidity is almost always less than 30%. Usually, in the middle of summer, it's mostly in the teens......we're basically high desert. Stay cool, they say only about another week or so of this.

06 GCO, Dk Khaki, QDII, Flshing Hi 3rd Bk Lt, MDS "ON" Lt, Airtab Vortex Gens, Debadged, Fumoto Drain Valve, BT Catch Can, Chopped EGR Tube, SRT8 CAI, AFE Air Filter, 6spd 545RFE, Sonnax Trans Line Press Booster, SC Tuner W/Adv Trans Tune App, DS and HP tuners, Transgo Shift Kit, ARH Long Tube Hdrs w/3 in Magnaflow/Xlerator AP Exh Sys, Bilsteins, SRT Springs/Sways, Cust Eng Cvr, SRT8 frt/rear bumpers, FRI Sidewinder Cam w/6* advance/6.1 valvetrain, SLP 25% UD Pulley, BBK true 90mm T-Body, SOS Ign Coils w/.060 spark plug gaps, TEA ported/milled heads w/new valve seats, SRT Reps with 265/45&295/40X20's. Also 05 Hemi LX modded exactly like WK and Comp Cammed 06 300CSRT8 soon to be replaced by 2021 Tesla Model S Plaid with 1020 hp and 1050 lb. ft. of torque.
90grandoneer is offline  
post #8 of 8 Old 07-01-2021, 07:44 PM
yzjwk
Registered User
 
yzjwk's Avatar
2005 WK 
 
Join Date: Apr 2011
Posts: 2,323
Quote:
Originally Posted by DM2 View Post
I am encountering an issue with a 2005 Jeep Grand Cherokee equipped with the 5.7 liter Hemi V8 where if a driver takes his foot off the brake at a standstill the Grand Cherokee wants to accelerate on its own. The brake pedal has to be pressed hard to keep it from moving at a standstill. I replaced a faulty throttle body with a new Mopar unit about a year ago. The problem just started recently, does anybody know what is causing this issue? Is this issue related to the throttle body? I recently heard if you replace the throttle body without flashing/updating the onboard computer that strange throttle related issues can occur later. Or is something else causing this issue? Thanks in advance for your help with this.

........
What are your RPMs sitting at idle? Are they different between a warm engine and cold?
Definitely need a good scanner but If the engine is revving or surging in drive but not in park and neutral, I would check the PCV, MAP and vacuum lines and check the Throttle body for carbon build up.

5 and counting :05 WK 5.7 HEMI
90 YJ Islander 4.2L
94 ZJ Ltd 5.2 ,00 WJ 4.0
2010 MK Patriot
yzjwk is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the JeepForum.com forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid e-mail address for yourself.



Email Address:
OR

Log-in











Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome