Standard Cruise Control

[RE76]

Hi I’m new to the Forum. I have a 2018 JLU 2.0T with automatic transmission. I have noticed lately while on cruise control let’s say 30mph, when I get on a downhills my rpm’s will shoot all the way from 1600 to 4500 and will engine brake hard. My wife has a 2022 Gladiator Willis and it doesn’t do that at all. It just started doing that a few weeks ago. At first I thought it was a result of installing a Mishimoto performance intercooler pipe and their cold air intake. But I don’t think that would have any impact on the CC. I also had a Pedal Commander which I unplugged but my issue continues. I got a hold of the dealership and said to bring it over, which I’ll do next week when I get back to town. I’m just wondering if anyone has experienced the same problem.

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[Some Random Guy]

It still sounds like hill descent. A smaller engine (your 2.0T) and lower rolling resistance (different tires) could easily explain this.
Don't listen to me though, I still row.

 

[Chupacabra]

I have standard CC with the 2.0T, never had anything like that happen. Generally it works pretty well.

 

[RE76]

I have 33 inch tires and 2.5 inch lift but never had any issues with it. My gas mileage just went down 2 miles from factory settings. But the cruise control issue started around 2 weeks ago, and is only going down hill. Is just weird.

 

[Dyolfknip74]

I have 33 inch tires and 2.5 inch lift but never had any issues with it. My gas mileage just went down 2 miles from factory settings. But the cruise control issue started around 2 weeks ago, and is only going down hill. Is just weird.

Very odd. Maybe indicative of a failing speed sensor?
......interesting to see what dealer says.

DO NOT tell them about Pedal Commander or leave any evidence. Theyll use it as an excuse to void warranty for anything related to it.

 

[aldo98229]

Your wife’s Gladiator has a larger engine, either the 3.6 V6 —or the 3.0 EcoDiesel. Gladiators also come standard with lower gearing: my understanding is Gladiator’s tallest gearing is 3.73, as opposed to 3.45 on JLs. These two differences alone will make your engine have to wind up higher to maintain speed on a steep descent.

As to why it’s doing it more lately...who knows...

 

[DaltonGang]

Doesn't sound normal, in any engine/tire combination.

 

[roaniecowpony]

Interesting discussion. I have a 2018 3.6L, Auto. I haven't used the cruise control on a steep hill descent. I have a hill near me to try it. I'll do it as soon as the dealer finishes my steering box replacement.

 

[GATORB8]

It's maintaining speed right? Isn't that what you want it to do? With out brake control it needs to use engine braking to maintain.

The 3.6L has a slightly higher compression ratio and is compressing 80% more volume, so it would need less RPM to produce the same amount of engine braking.

There is some TCM action that goes on as well. For example, in my Ram towing downhill, tow/haul sharpens the engine braking and will maintain speed within a mph or so, without tow/haul the engine braking is less noticeable and will allow a greater increase in speed.

 

[Bob Burd]

I don't think I've seen 4500rpm, but my cruise contol has always used engine braking on downhills. I like the feature.

 

[RE76]

It's maintaining speed right? Isn't that what you want it to do? With out brake control it needs to use engine braking to maintain.

The 3.6L has a slightly higher compression ratio and is compressing 80% more volume, so it would need less RPM to produce the same amount of engine braking.

There is some TCM action that goes on as well. For example, in my Ram towing downhill, tow/haul sharpens the engine braking and will maintain speed within a mph or so, without tow/haul the engine braking is less noticeable and will allow a greater increase in speed.

Yes it holds speed in normal conditions and mild hills is only the steep ones that throws it into the high rpm’s and and heavy engine breaking.

 

[RE76]

Very odd. Maybe indicative of a failing speed sensor?
......interesting to see what dealer says.

DO NOT tell them about Pedal Commander or leave any evidence. Theyll use it as an excuse to void warranty for anything related to it.

The pedal commander is gone for now lol. I thought the same thing and removed it. I forgot to mention I have 0 engine codes showing.

 

[RE76]

I don't think I've seen 4500rpm, but my cruise contol has always used engine braking on downhills. I like the feature.

That’s my point it just started acting this way about two weeks. ??‍

 

[RE76]

Your wife’s Gladiator has a larger engine, either the 3.6 V6 —or the 3.0 EcoDiesel. Gladiators also come standard with lower gearing: my understanding is Gladiator’s tallest gearing is 3.73, as opposed to 3.45 on JLs. These two differences alone will make your engine have to wind up higher to maintain speed on a steep descent.

As to why it’s doing it more lately...who knows...

Yes her gladiator has 3.73 gear ratio and the 3.6 V6. I’ve owned this Jeep 3 years now and only have 13000 miles on it, and been driving the same roads and steep hills in my neighborhood and the engine would climb maybe to 2100 or 2200 in rpm’s on the same hills. Is like it’s behind sensing the speed change. On hills not to steep it will climb one or two miles and hardly go up in rpm’s. I’m just confused with this issue. The dealership when I talked to them didn’t sound like they had any idea either. I been lucky with them have taken care of us this is the 3rd vehicle I have bought from them.

 

[aldo98229]

Yes her gladiator has 3.73 gear ratio and the 3.6 V6. I’ve owned this Jeep 3 years now and only have 13000 miles on it, and been driving the same roads and steep hills in my neighborhood and the engine would climb maybe to 2100 or 2200 in rpm’s on the same hills. Is like it’s behind sensing the speed change. On hills not to steep it will climb one or two miles and hardly go up in rpm’s. I’m just confused with this issue. The dealership when I talked to them didn’t sound like they had any idea either. I been lucky with them have taken care of us this is the 3rd vehicle I have bought from them.

Have you gotten larger tires?

That’d alter the engine’s RPMs and the transmission’s shift points.

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