Manual Transmission Jumps Forward

[CBelair]

Hi - I have a 2024 Willys manual transmission that I bought new and have been driving for about 18 months. Since day one I noticed that when I first start to drive I have to be VERY careful because the Jeep will basically speed up on it's own and almost jump forward while I'm in first and second gear. This is my third Jeep and the others did not do this. Without me touching the gas or the clutch just speeds up - shockingly fast. It is much worse in cold weather but this is a year round daily occurrence. I don't even need to touch the gas from a full stop in first gear - just let up on the clutch and I'm moving without stalling. I've even done it at a full stop and in 2nd gear - just let up on the clutch and off we go! Taken her into the dealer several times and been told this is totally normal. I have NEVER had a manual transmission act like this and been driving manual transmission my whole life. This is my first Willys - 2 other jeeps were 2 door "sports", plus had other vehicles...BMW etc. Is this just a Willys thing or is there really something wrong? It feels a bit dangerous. - THANKS!

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[Steve104]

I believe that what you are describing is attributable to the ECM controlling the throttle and not the transmission itself. This has been a topic. https://www.jlwranglerforums.com/forum/threads/involuntary-acceleration.118908/

 

[GATORB8]

Looks like your Willy's has 4.10s and the first gear is probably lower than you are accustomed to.

I'd expect high idle to warm the engine up until it's at temp, which is why it'd be worse then. Once warm, you should be able to roll out and have it chug along at idle if it has the power.

A good thing about it, is one of the fixes would be to just throw on some bigger tires for a higher effective gear ratio.

 

[GATORB8]

To add a little for your comps. Your sports likely had a 3.45 rear end, with the same transmission and engine, your Willy's should feel 20% "quicker" with the 4.10s.

Depending on your BMW 1st and rear end were likely a bit taller for speed, and likely turbo'd with less grunt at sub 1k RPM. My last manual Bimmer also had a clutch release setup that would still feather the release even if you dropped it.

 

[MauiSteve]

Agreed, sounds like the ECM is making the idle high when the engine is cold.

 

[ecomguy]

It’s likely to heat up the catalytic converter to get them up to temp more quickly. An emissions thing.

“Most of the pollution put out by your car occurs during the first five minutes before the catalytic converter has warmed up”

https://web.archive.org/web/20120417183354/http://www.nsls.bnl.gov/about/everyday/catalytic.asp

 

[GeoTracker]

Calibrate your throttle too. Made a world of difference for mine.

 

[azwjowner]

Agreed, sounds like the ECM is making the idle high when the engine is cold.

This is exactly it. Every time I cold start my manual I have to let it idle until the RPMs drop from 1500 back down to a normal idle. Otherwise the Jeep is pulling hard while I try to shift. The net effect of this is I waste more gas and emissions than if I were able to just start driving. Way to go Stellantis.

 

[Skytow]

My manual ‘21 Rubicon does this too but oddly when going down hill. Weird I know but, I live on top of a hill. If I coast down the Jeep ADDS power. I know, I know, you are thinking “ hey dummy you are going down hill, of course it speeds up”. It’s not that, it is adding throttle. If I coast down in neutral the engine revs to about 2000 rpm. Does it in gear as well. I always assumed it was some emissions related thing. Happens only when cold but even after it has idled down from a cold start.

 

[Reinen]

That's the problem with modern manuals. You have a smart engine and it's doing things for [reasons]. But the transmission doesn't get the memo and neither do you. You just have to manually deal with whatever the engine wants to do.

 

[Steve104]

My manual ‘21 Rubicon does this too but oddly when going down hill. Weird I know but, I live on top of a hill. If I coast down the Jeep ADDS power. I know, I know, you are thinking “ hey dummy you are going down hill, of course it speeds up”. It’s not that, it is adding throttle. If I coast down in neutral the engine revs to about 2000 rpm. Does it in gear as well. I always assumed it was some emissions related thing. Happens only when cold but even after it has idled down from a cold start.

I have the same deal when coasting down the hill after work. So I sit in the parking structure until the idle drops all the way down. I'm wasting gas to save on emissions. Doesn't seem quite right.

 

[RAD1]

Mine does this too. I park in a parking garage at work. When I leave at the end of the day if I put it in 2nd it feels like I'm flying out of the garage. People literally jump out of the way when they hear me coming lol.

Just another Jeep thing.

 

[Scott97]

Hi - I have a 2024 Willys manual transmission that I bought new and have been driving for about 18 months. Since day one I noticed that when I first start to drive I have to be VERY careful because the Jeep will basically speed up on it's own and almost jump forward while I'm in first and second gear. This is my third Jeep and the others did not do this. Without me touching the gas or the clutch just speeds up - shockingly fast. It is much worse in cold weather but this is a year round daily occurrence. I don't even need to touch the gas from a full stop in first gear - just let up on the clutch and I'm moving without stalling. I've even done it at a full stop and in 2nd gear - just let up on the clutch and off we go! Taken her into the dealer several times and been told this is totally normal. I have NEVER had a manual transmission act like this and been driving manual transmission my whole life. This is my first Willys - 2 other jeeps were 2 door "sports", plus had other vehicles...BMW etc. Is this just a Willys thing or is there really something wrong? It feels a bit dangerous. - THANKS!

What you have described does not sound normal or safe. I have a 2024 Willys with the 6 speed MT. I have had it since January of 2024. Have not experienced any of these issues. It idles at 1000RPM on a cold start. Once warmed up, it only idles at 500RPM. As others have suggested, the throttle calibration should be checked. The dealer should have checked this. Maybe try another dealer.

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