Hi guys,

I'm hoping to get some ideas about a problem I have...

I'm driving my 2010 1500 Ram for 18 months now and experienced the problem since day one.

It has a 5.7 V8 Hemi, with a dual fuel (LPG) system.

The problem I have is that when I'm driving on a constant speed of about 70km/h, the engine starts shaking. I feels like it tries to gear up to the highest gear, but then doesn't have enough torque to run in that gear and that gears down again. When I accelerate at this point, the shaking becomes worse for a moment until it finds the right gear. Two minutes later I have the same problem again.

I don't experience this problem on fuel, only when I'm on LPG.
Recently I discovered that when I switch to semi-automatic 5th gear, the problem is not happening.

The dealership has been looking at this problem for more than a year now, together with the LPG-installer. But they can't seem to find the cause.

Some idea's that came forward as possible causes:

- maybe this is caused by the system that switches off 4 cylinders in order to be more economic? In combination with the LPG, It might not have enough power to run normally?

- maybe the gear box switches to the highest gear too soon for LPG-available torque. By "too soon" I mean at an engine speed that is too low. Typically this phenomenon starts when the engine runs continuously at 1400RPM. During the shaking, the engine speed goes down to 1200RPM for about 10 seconds, after which it goes back to 1400-1500RPM.

- The dealership also mentioned the possibility of a malfunctioning gear lock system for the highest gear.

The LPG system has been checked, one time they discovered a broken nozzle, but that didn't solve the problem.


Maybe it has nothing to do with this problem, but I also have a systematic problem that at remote start, the engine stops after about 5 minutes, probably when switching from fuel to LPG.


I would really appreciate some feedback of more experienced Ram-drivers, or even Hemi-drivers. I'm quite desperate about it. For now I keep driving in 5th semi-automatic gear.

Thanks a lot!

Christian

 

Here's your problem, just as you stated. It was the first thing that came to mind, especially since you claim not enough power. Even when you run gasoline, the 4cyl isnt enough to keep a big heavy truck going at a steady speed on highway. I always had that same trouble so I ended up buying a tuner and disabling that useless feature.
LP doesn't provide no where near the power as gasoline does, so when the truck is struggling with gasoline on 4cyl, the LP isnt going to cut it. My suggestion to you ise deactivate the MDS and go from there. Many tuner support this feature.
Diablo predator which can be custom tune altered
Superchips Flashpack/ 3865/Cortex 3950 cannot alter much of tunes other than fuel trims but they allow significant trans tuning.
With the Superchips Advanced trans tuning and MDS disabled, I get better city mpg's and very close to the same highway MPG's as when the crapy mds was enabled.
before 11/17, now 13/16. i do mostly city, so I benefit greatly from disabled mds and drawn out trans shifts which keep truck in powerband and not lugging. Hemi's like 2k-2200rpms for optimal mpgs/performance.

 

Hi Rich,

Thanks so much for your reply. I wasn't aware that there were problems with the system running on gasoline. Also, I didn't know that the power difference between gasoline and LPG were so big. This indeed explains a lot then.

I'll take this back to the dealership to see for the best way to deactivate the system (it's still covered by warranty). I'll post the results here.

 

I agree with dirtydog with one note. You also have a lock up torque converter. If there its a broken part, that would be it. I have a2011. And I understand there is no tuner yet for me. I would love to change my shift points. Good luck.