Hard shifting + no shifting = auto tranny issue? - JeepForum.com
 
LinkBack Thread Tools
post #1 of 8 Old 06-13-2009, 11:35 AM Thread Starter
DoubleBET
Registered User
1996 XJ Cherokee 
 
Join Date: Aug 2006
Location: NJ
Posts: 137
Hard shifting + no shifting = auto tranny issue?

Hey guys, yesterday I began experiencing the following issues seemingly out of the blue, in the middle of driving down my local highway:

- While accelerating from stop, the jeep would pick up speed up until around 25 mph, but not readily switch into the next gear unless I pushed down extra hard on the gas. When it did change gears, it would be a hard shift. RPMs would remain around 2200 until the shift, after which they would skyrocket to around 4500 and slowly back down.
- After the gear switch, RPMs would go back down to 2200 and stay at 2200 while the vehicle slowly accelerates. Sometimes the jeep would make another hard jump to the next gear if the pedal was floored, other times flooring it would do almost nothing, and RPMs would remain at 2200 as the jeep slowly accelerated to upwards of 55 mph. This would be a very slow acceleration, and it felt like the entire engine was straining.

It's very odd that the RPMs would stay at 2200 at higher speeds, since normally flooring it at just about any speeds would cause RPMs to shoot up to at least 3500 and the jeep would accelerate quickly. The current issue reminds me of what it feels like when I'm towing something/pulling a heavy vehicle. It's as if the engine's straining, limiting itself to 2200 RPMs to limit the strain.

Other details:
- Oil pressure is a bit low, never goes above the halfway mark, usually hovering around the 1/4 mark on the gauge. Normally it's a bit higher. Dipstick shows engine oil's slightly low but above the min.
- Before yesterday, the past few days while starting the jeep in the morning, the very first time I hit the gas, the engine sputtered/almost stalled, but was then fine. This never happened before this week.
- Transmission fluid is at the proper level but hasn't been changed in a long time. In the past my mechanic had advised me not to change it because a new (and more grainy) fluid might put extra strain on the transmission/result in harder shifting.

So that's my problem. Any thoughts? My mechanic's supposed to look at it on Tuesday. I'm quite terrified that it will be a tranny issue, in which case my jeep is probably as good as dead, since I won't have the cash to repair it


1996 XJ, 4.0L Inline-6 High Output, 3" lift, 31" Couragia M/T tires, Flowmaster 50 DeltaFlow exhaust
DoubleBET is offline  
Sponsored Links
Advertisement
 
post #2 of 8 Old 06-13-2009, 03:05 PM
CJ7-Tim
Real Jeeps have dents
 
CJ7-Tim's Avatar
2000 XJ Cherokee 
 
Join Date: Apr 2002
Location: out in the garage - Minneapolis
Posts: 24,530
Quote:
Originally Posted by DoubleBET View Post

- Before yesterday, the past few days while starting the jeep in the morning, the very first time I hit the gas, the engine sputtered/almost stalled, but was then fine. This never happened before this week.
- Transmission fluid is at the proper level but hasn't been changed in a long time. In the past my mechanic had advised me not to change it because a new (and more grainy) fluid might put extra strain on the transmission/result in harder shifting.
Transmissions with weird behavior ( and the strange acceleration issues ) point you in the direction of sensor issues that are confusing the TCU. Check the TPS and NSS.

Find a new mechanic. I don't how your mechanic can do any work with his head so far up his *ss. Change the transmission fluid. Trans fluid is never "grainy", only burnt and contaminated. Use only the Factory Recommend Dexron III/Mercon. Drain 3-4 quarts from the pan using the drain plug and re-fill. Do this once a week for 3-4 weeks or until the trans fluid looks and smells normal. High pressure transmission fluid flushes are what people should be referring to as they do tend to dislodge debris.

.

A recent Gallup public opinion poll shows the NRA, at 58% approval, has a higher approval rating than either Hillary Clinton or Barack Obama.

Progressive Liberalism: Bringing you new Healthcare ideas so wonderful, they have to include mandatory participation ...

Originally Posted by Ronald W. Reagan: Government is not the solution to our problems; Government is the problem.
CJ7-Tim is offline  
post #3 of 8 Old 06-13-2009, 04:36 PM Thread Starter
DoubleBET
Registered User
1996 XJ Cherokee 
 
Join Date: Aug 2006
Location: NJ
Posts: 137
Do you think an issue so dramatic as this could arise suddenly if it were a sensor? Pardon my noobishness but what are the TCU, TPS and NSS? Can a general mechanic check those or will I need to bring it to a transmission specialist?

Hmm, I see what you mean about not changing the fluid, it seems counter-intuitive. However it also seemed counter-intuitive for my mechanic to want to do less work on my car, hence making less money. So I never really questioned his advice...

1996 XJ, 4.0L Inline-6 High Output, 3" lift, 31" Couragia M/T tires, Flowmaster 50 DeltaFlow exhaust
DoubleBET is offline  
post #4 of 8 Old 06-13-2009, 07:41 PM
CJ7-Tim
Real Jeeps have dents
 
CJ7-Tim's Avatar
2000 XJ Cherokee 
 
Join Date: Apr 2002
Location: out in the garage - Minneapolis
Posts: 24,530
See these two links for more information -
http://www.jeepforum.com/forum/f11/cherokee-stock-specs-26256/
http://www.jeepforum.com/forum/f11/tech-faq-links-tsbs-89273/


NSS - Neutral Safety Switch, Transmission Position Sensor
TPS - Throttle Position Sensor
TCU - Transmission Control Unit

The engine computer (ECU) and the TCU work together with data from the TPS and NSS to determine shift points and transmission status. Bad data from any sensor will cause the computers to default to limp mode that is supposed to protect the engine and trans from damage.

.

A recent Gallup public opinion poll shows the NRA, at 58% approval, has a higher approval rating than either Hillary Clinton or Barack Obama.

Progressive Liberalism: Bringing you new Healthcare ideas so wonderful, they have to include mandatory participation ...

Originally Posted by Ronald W. Reagan: Government is not the solution to our problems; Government is the problem.
CJ7-Tim is offline  
post #5 of 8 Old 06-13-2009, 11:56 PM
alexrule123
Registered User
 
alexrule123's Avatar
2001 XJ Cherokee 
 
Join Date: Dec 2005
Location: Jacksonville
Posts: 7,340
Sounds like the throttle position sensor to me

Quote:
The great thing about UDP jokes is no one cares if you get them or not.
2001 Cherokee Limited: My Build Thread
2005 Pontiac GTO 6.0L (DD)
May 2013 COTM
alexrule123 is offline  
post #6 of 8 Old 03-11-2011, 06:14 AM
mayeni
Registered User
1992 XJ Cherokee 
 
Join Date: Feb 2011
Location: kbh
Posts: 146
Hey
What does the NSS do?
mayeni is offline  
post #7 of 8 Old 03-11-2011, 06:25 AM
egodfrey
Web Wheeler
 
egodfrey's Avatar
1998 XJ Cherokee 
 
Join Date: Jul 2009
Location: Whitney Point
Posts: 3,318
Check your TPS

So many people to thank here's a start to the list
Spidertrax, Yukon, rustys, warn, branik, PSC, advance adapters, Bad wheels, interco, essentially off-road. And many more

Most of all thanks too Ian Johnson and the xtreme off-road crew for all their work, and 4 wheel to heal for their part in it too.
egodfrey is offline  
post #8 of 8 Old 03-11-2011, 08:06 AM
tjwalker
It's the crank sensor!
 
tjwalker's Avatar
1999 XJ Cherokee 
 
Join Date: Nov 2007
Location: Central Minnesota
Posts: 8,745
If this were mine, I'd definitely start with the throttle position sensor. Failure of this component is not uncommon and it is directly involved with transmission shifting characteristics.

99 Cherokee, 4.0 AW4, NP242
Past Jeeps: 49 Willys, 81 Scrambler, 88 Comanche
Without "data", all you have is an opinion!
tjwalker 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









Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




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



Similar Threads
Thread Thread Starter Jeep Forums Replies Last Post
ax5 tranny shifting hard while engine is running wdwrd_fred XJ Cherokee Technical Forum 1 01-09-2009 03:33 AM
Weird Transmission Shifting Issue mclovin80 XJ Cherokee Technical Forum 2 08-18-2008 09:09 PM
hard shifting auto transmision in a 98 cherokee bikejerk XJ Cherokee Technical Forum 3 07-29-2008 08:12 PM
issue when manually shifting AW4 mrtosh XJ Cherokee Technical Forum 5 03-21-2008 09:26 AM
Auto tranny shifting WarHorseXJ XJ Cherokee Technical Forum 4 10-22-2005 09:50 PM

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