Pick your brains

Spree

Spree

Dedicated LVC Member
Joined
May 26, 2012
Messages
1,164
Reaction score
68
Location
Cambridge City, IN
No one ever talks on the Blazer or Jeep forums. So I thought I would ask a question that has nothing to do with Mrk's.
Everyone share's information here and maybe one of you guy's know something about Jeeps.
About a week ago I noticed that our Jeep does not want to shift on it's own, sometimes only. You have to let your foot off the gas and then it will shift. Could this be a module, vacuum line or something easy to replace and fix? Or could this be a bigger problem getting ready to arise? There is no codes or lights lit on the dash.
It's a 2004 Jeep Grand Cherokee Limited V8 but not the high output with all the goodies. This is my wife's dd, with 155K and climbing fast.
Anything you guy's can give me to check would be greatly appreciated.
I'm still a little transmission stupid!
 
Fluid looks good and full. When I step on the gas it down shifts and it's like there's nothing there. The rpm's are up around 4000 to 4500 and there's just no power until I let off the gas a little, then it will finally find the gear. I wouldn't say it's in neutral because it's still moving, Just no power. Otherwise if I drive it normal there's absolutely nothing wrong.
 
I was looking at a 5.9L Limited ZJ before I got my '96 LSC...it had sort of erratic shifting behavior, and one thing I found is that the TPS (throttle position sensor) could get fouled up needing a cleaning. If it sends false readings, it can mess up your shift points. Clean that up and see if anything changes.
 
You cant clean a TPS.

System is drive by wire anyway and a TPS would have nothing to do with a slipping transmission.

Your transmission is toast. Dodge has had crap autos in their trucks/SUVs for years. If you do not do a filter and complete trans flush every 60k on them then they will fail between 120k and 160k. See it over and over and over again.
If you have not serviced the trans then thats your problem.

Check the fluid. Dont make sure its there and full, look at and smell the fluid. use a white napkin and rub the stick on it. If you see anything other than red you have problems. If its solid brown the trans is toast. If its red and a little brown but still smells sweet then maybe a service will help. If its red and brown and smells like varnish then the trans is toast.

People really need to service their vehicles. Sure everyone thinks they take care of them by changing the oil every 3000 miles but you have to remember, rear end fluid needs to be serviced every 75k give or take, trans needs to be serviced every 45-60k, fuel filters should be done every 6-7 oil changes, brake fluid should be changed every couple years, coolant should be flushed every couple years as well.

These are the life blood of the engine and if not kept clean the car will not take care of you. My truck has 155k on it and is serviced as it should be. It runs, drives and shifts just like a brand new truck because of it.
 
"Factory 4.6L and Trans unopened and unmolested"

^That was your biggest mistake.


Spree, there is a big difference between "unmolested" and "unmaintained". Hate to be the bearer of bad news especially coming from the guy with a perfectly shifting car that is very much modified and shifts to the moon and is driven like a race car frequently. Don't shoot the messenger. LaserSVT is spot on here. You should have had a closer relationship with your transmission after all these years. You wouldn't leave your kids locked up in the basement would you??
 
LaserSVT said:
You cant clean a TPS.

System is drive by wire anyway and a TPS would have nothing to do with a slipping transmission.

Your transmission is toast. Dodge has had crap autos in their trucks/SUVs for years. If you do not do a filter and complete trans flush every 60k on them then they will fail between 120k and 160k. See it over and over and over again.
If you have not serviced the trans then thats your problem.

Check the fluid. Dont make sure its there and full, look at and smell the fluid. use a white napkin and rub the stick on it. If you see anything other than red you have problems. If its solid brown the trans is toast. If its red and a little brown but still smells sweet then maybe a service will help. If its red and brown and smells like varnish then the trans is toast.

People really need to service their vehicles. Sure everyone thinks they take care of them by changing the oil every 3000 miles but you have to remember, rear end fluid needs to be serviced every 75k give or take, trans needs to be serviced every 45-60k, fuel filters should be done every 6-7 oil changes, brake fluid should be changed every couple years, coolant should be flushed every couple years as well.

These are the life blood of the engine and if not kept clean the car will not take care of you. My truck has 155k on it and is serviced as it should be. It runs, drives and shifts just like a brand new truck because of it.
Click to expand...

This is good advice, but I gotta mention this. We drive all over the U.S. in our company truck which is a 2002 Dodge Cummins Diesel; my boss takes terrible care of this truck. The tranny is the last year they used the 47RE transmission in the Cummins as Dodge went to the 48RE in 2003.

Point is our truck just turned over 412,000 miles on the same transmission. We did have one problem at 395,000 where the truck was reluctant to shift out of 1st sometimes. After having it fixed, it turned out to need a band replacement (which they did with the tranny in the truck) for almost $600.

That's A LOT of miles on one of those trannys; they can't be THAT badly built! Talking about the rear end, I don't think he's ever had the fluid changed in that and it chatters when we turn (it's a posi).
 
NetKeym said:
This is good advice, but I gotta mention this. We drive all over the U.S. in our company truck which is a 2002 Dodge Cummins Diesel; my boss takes terrible care of this truck. The tranny is the last year they used the 47RE transmission in the Cummins as Dodge went to the 48RE in 2003.

Point is our truck just turned over 412,000 miles on the same transmission. We did have one problem at 395,000 where the truck was reluctant to shift out of 1st sometimes. After having it fixed, it turned out to need a band replacement (which they did with the tranny in the truck) for almost $600.

That's A LOT of miles on one of those trannys; they can't be THAT badly built! Talking about the rear end, I don't think he's ever had the fluid changed in that and it chatters when we turn (it's a posi).
Click to expand...
Just like anything in life there are exceptions to the rule. I have a customer with an 01 Escape that has over 500,000 miles and has never replaced anything other than timing belts and spark plugs. I also have a customer that has a 6.4 Ford F-350 thats on his 5th engine in 125k miles.

I do a lot of online searching for cars and I would say 80% of the Jeeps and Dodge trucks for sale for good prices are for sale due to "transmission is starting to slip". Very rarely are those vehicles cheap because of blown motors or body dammage, its all too often a trans issue. Hell my 97 had 110k on it and started to lose the trans and I had a reciept for a service done at 65k. I serviced it again and it only made it worse.

Dodge trannies suck. Even their TD manual trans are goofy as fock.
 
KStromberg said:
"Factory 4.6L and Trans unopened and unmolested"

^That was your biggest mistake.


Spree, there is a big difference between "unmolested" and "unmaintained". Hate to be the bearer of bad news especially coming from the guy with a perfectly shifting car that is very much modified and shifts to the moon and is driven like a race car frequently. Don't shoot the messenger. LaserSVT is spot on here. You should have had a closer relationship with your transmission after all these years. You wouldn't leave your kids locked up in the basement would you??
Click to expand...

What was my biggest mistake? My Mark has 197,000 on it and the trans has never been opened and runs and shifts like new. Is that unmaintained? Or did I just get lucky with this trans? I know guy's that "maintained" there vehicles and didn't get that kind of mileage out of them.
The Jeep we only had for 4 years now, the trans doesn't feel like it's an internal issue as much as it does a control issue. Is there something that controls when the shift points are when you step on the gas? Is this vacuum or electrical? Like I said when driving normal to moderate it shifts and picks up speed just fine. When you step on it, it falls on it's face until you let up off the gas a little then it will shift and start moving.....This may be a better description of what it's doing
 
From your description of the way it drives, sounds like you might have plugged cats. ""catalytic converters"" Alot of people bring vehicles to our shop saying they have trans problems and it turns out to be cats. I'm not dogging on you, just saying it's easy to mistake for a trans problem. Of course it's also hard to diagnose a car over the computer.
 
Yeah but he also says he hits the gas, RPMS jump and the car does not accelerate. That to me is trans slippage.

Check the fluid as I earlier said and report back. Knowing the trans fluid color and smell will tell you. Cars fluids and exhaust will tell you anything you need to know about a cars running condition. Just have to know how to read it.
 
Thanx for all the response!

LaserSVT, the wife has it today but it will be home tomorrow. I'll do what you said and post my findings.

Correct, when I hit the gas it down shift's but it doesn't feel like it's slipping. It stills pulls just no power until gas it let up on a little.
I figured if it was slipping it would do it all the time.
It's like something is telling it not to shift at WOT.
 
Ah, well that changes things. I missunderstood when you said RPMS go up but it does not accelerate. If its downshifting then the TPS is fine. As someone else said, you may just have fouled cats.

Need to get a scanner on it.
 
chargerxr said:
Plugged cats.
Click to expand...

That's easy to check, too. Step out back of your vehicle and have someone rev the engine. If the exhaust isn't blowing like crazy, cats.

In the past, I've had vehicles with plugged cats and usually the engine has a hard time revving up. Of course, I've never had a Mark VIII with plugged cats so I don't know if they act like that or not. :confused:
 
You must log in or register to reply here.

Members online

No members online now.
Total: 96 (members: 0, guests: 96)
Back
Top