Bucks hard taking off

Chapman4266

Chapman4266

TJ Enthusiast
Joined
Mar 2, 2019
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Location
Snyder TX
I have researched and have not found my exact problem.

Here it is. 06 Rubi 6 speed 94k. It just started this.

Taking off, only rarely, it stumbles hard one time as soon as i start moving. I call it a hard buck. I have had a CEL for months, and after it bucks the one time, the CEL disappears. It eventually comes back. I checked the codes, and the CEL I have always had most likely has to do with me gutting the cats. It has run perfect for a year since gutting them, so not concerned with that. It only stumbles one time hard for a fraction of a second, then runs perfect. It did it a couple times in a row 2 days ago, and today on my way home. Jeep is stock. Concerned about ECM. Anybody had exactly this happen? It runs perfect the rest of the time.
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Good morning gentlemen,

The common failures of a manual pcm are bad o2 sensors, low rpms and completely dying while driving. Have you had either of these symptoms?

I haven’t heard of a buck in a manual but I will ask my technician and will get back to you.

The summer heat and the location of the pcm causes a lot of issues. Some customers tell me that they can tap on their pcm and the Jeep will die.
 
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Wranglerfix said:
Good morning gentlemen,

The common failures of a manual pcm are bad o2 sensors, low rpms and completely dying while driving. Have you had either of these symptoms?

I haven’t heard of a buck in a manual but I will ask my technician and will get back to you.

The summer heat and the location of the pcm causes a lot of issues. Some customers tell me that they can tap on their pcm and the Jeep will die.
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I've been driving on hotter days than when it happened and everything was good. It is just a fraction of a second and picks right back up. It only does it when taking off. It's always been able to idle off like you would when driving a diesel big rig. I don't think rpms are the issue. It doesn't die while going down the road. When it "bucks" it seems the jeep is dying for just that fraction of a second. Hope that answers it. Thanks for the help
 
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Chapman4266 said:
I've been driving on hotter days than when it happened and everything was good. It is just a fraction of a second and picks right back up. It only does it when taking off. It's always been able to idle off like you would when driving a diesel big rig. I don't think rpms are the issue. It doesn't die while going down the road. When it "bucks" it seems the jeep is dying for just that fraction of a second. Hope that answers it. Thanks for the help
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That is exactly what it's doing ...dying... a PCM is probably going to be the answer.

we all are always hesitant because we know we want a sure diagnosis before we spend the money.

People over rate the cost of the PCM replacement... Think of it as a set of tires you only have to buy one time.

the reason I say that is people just cringe about buying a PCM ..but they will brag take pictures shop and get excited and show off a new set of tires that are only going to last so long and start going downhill the second you pull off the rack.
 
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AndyG said:
That is exactly what it's doing ...dying... a PCM is probably going to be the answer.

we all are always hesitant because we know we want a sure diagnosis before we spend the money.

People over rate the cost of the PCM replacement... Think of it as a set of tires you only have to buy one time.

the reason I say that is people just cringe about buying a PCM ..but they will brag take pictures shop and get excited and show off a new set of tires that are only going to last so long and start going downhill the second you pull off the rack.
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I'm leaning that way, just hope not. It doesn't even have 100k on it yet
 
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My technician thinks it is the pcm as well.

We are working diligently to decrease build time on the manual pcms as we now have an 06 manual to test out modifications. We are close to perfecting some repairs on the oem unit as well.

It just takes time and then current build time is 21 days because of the scarcity of the current parts we use.
 
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