At high speed does your transmission shift up and slows acceleration?

[NC-Dave]

Ok, ok I know these things aren’t designed for high speeds but I opened it up, on an open stretch of road, several weeks ago. Got it up to 98 mph and it was accelerating well then until I hit 98. Then, it shifted up two gears and then accelerated at a much slower pace. Is that normal? Not that I plan on driving that fast, normally, just found that to be interesting.

Has this happened to anyone else? I’ve got a 6.4 in my Grand Cherokee SRT and I can assure you, it doesn’t do it .

Thanks,

Dave

P.S. I was in Mexico at the time. ,

 

[jsalbre]

Ok, ok I know these things aren’t designed for high speeds but I opened it up, on an open stretch of road, several weeks ago. Got it up to 98 mph and it was accelerating well then until I hit 98. Then, it shifted up two gears and then accelerated at a much slower pace. Is that normal? Not that I plan on driving that fast, normally, just found that to be interesting.

Has this happened to anyone else? I’ve got a 6.4 in my Grand Cherokee SRT and I can assure you, it doesn’t do it .

Thanks,

Dave

P.S. I was in Mexico at the time. ,

You hit the speed limiter. Your Rebel (like all the others, and all Power Wagons) is limited to 99 MPH because the Goodyear Duratracs it comes with are rated to 99 MPH.

 

[NC-Dave]

Thanks Jsabre,

That's exactly the information I was looking for and explains the trucks reaction. I know it had more in it and was pulling like crazy up to 98 then it when in "like" a limp mode. Shifted up two gears and slowed in acceleration. Not that I need to go that fast but in this truck, (I have plenty of other to do that in) it's very capable. But I can see the tires might be an issue at high speeds, just not designed for it.

I called my Dealer, (who has been next to worthless, after the purchase) and they never got back to me on it. You'd think if they sold a truck with a sticker over $87K they call you back. Oh well got their money, I guess they don't need repeat business.

Thanks, Dave

 

[Firebird]

Yep, speed limiter

 

[Dewey]

My kids said that I need to baptize the truck. Lol. This mean you need to go 100 mph. On the way home from the BMX track I did 106 mph. My boys thought it was awesome. It did not do it very fast but its a truck. 22 2500 big horn 6.4 4.10 gears it probably had 400 miles at the time.

 

[JimKIII]

If he were to get different tires than the Goodyear Duratracs that are rated higher than 99mph, could he change the limiter with something like AlphaODB?

 

[jsalbre]

If he were to get different tires than the Goodyear Duratracs that are rated higher than 99mph, could he change the limiter with something like AlphaODB?

Unfortunately not. You need engine tuning to change the speed limiter. It does show in AlfaOBD, but those that have succeeded in changing it have found that it resets itself to 0, requiring an ECM replacement to get the truck moving again.