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Thread: Doing a conversion on a Ram with 5.7 Hemi MDS Engine

  1. Default Doing a conversion on a Ram with 5.7 Hemi MDS Engine

    Has anyone on here done a cng conversion on a Dodge Ram 5.7 Hemi with the MDS Engine? If so,how did it work? I am wondering if these kits will allow the mds to kick in properly reducing down to 4 cyl. operation. Also if anyone has done one of these were there any other problems. What kit would be the best to use? How was the performance on cng? Also is the stock internals going to hold up over the long haul? I have heard about hardened valves/seats and was wondering if these new engines came factory with the hardened valves or should they also be added. I heard that some of the older chevys had problems with this.

    Rick
    Last edited by Rickinokc; 07-03-2011 at 02:13 PM.

  2. #2

    Default Re: Doing a conversion on a Ram with 5.7 Hemi MDS Engine

    Rick,
    You are a better man than I Gunga Din. I personally am not concidering any Dodge conversions until HP Tuners Dodge software is out of beta.
    Dodges have been a real trick for any performance enhancements including CNG. As for the valves, I'm not sure if Dodge is following the same flexfuel/alt fuel ready engine schema that Ford and GM are.
    Good luck, the dual plugs and MDS would make for an awesome conversion if done correctly.
    Your Friendly Nazi Squirrel Administrator

  3. #3

    Default Re: Doing a conversion on a Ram with 5.7 Hemi MDS Engine

    I just started looking into a conversion kit for my Ram 5.7 hemi. I found two companies that make kits for these engines; Parnell and Ecofuel. I am going to talk to my CNG mechanic this week to see what he says. If anyone has any feedback on these systems I would love to hear it.

  4. Default Re: Doing a conversion on a Ram with 5.7 Hemi MDS Engine

    So did you find out anything on the hemi conversion? Also,has any of these tuners broken the ecu code on the 2011 5.7 Ram?

  5. #5
    Join Date
    Dec 2011
    Location
    Edmond. Oklahoma
    Posts
    3

    Default Re: Doing a conversion on a Ram with 5.7 Hemi MDS Engine

    I have a 2010 Ram Hemi converted to CNG. My installer and I are still sorting out some issues. At first, it ran without throwing any DTC's but was running lean and would stall at idle or rev very high and hunt for gears when accelerating on the highway. The CNG system would also reset itself and switch to gasoline when feathering the throttle and switching in/out of MDS.

    After extensive troubleshooting, he now has it running fine but with a permanent check engine light that disables MDS (meaning it's emissions-related). He has told me that this is just something I have to live with, which is unacceptable to me.

    My current best guess is that the O2 readings aren't jiving with the ECM and are throwing the code. I'll be double-checking exactly which codes it's throwing when I get back in town this weekend. If the DTC's are from the O2 sensors or something along those lines, any Dodge tuner shop with CMR tuning software can flash a Predator tuner with a custom tune that disables the emissions codes or expands the "safe" range of sensor readings. It's a common thing among the SRT Hemi Charger/Challenger guys when swapping in high performance headers. This SHOULD clear the DTC and CEL and enable MDS to function properly. I'll report back if/when that works.

  6. #6
    Join Date
    Jun 2008
    Location
    Birch Bay, Wa & Joshua Tree, Ca
    Posts
    1,133

    Default Re: Doing a conversion on a Ram with 5.7 Hemi MDS Engine

    You might with comparing your O2, fuel trim readings, and injector PW (gas to CNG) If the fuel trim is running high on the plus side on ng increase the low pressure side of the regulator 5 to 10 pis and see if the long trim numbers drop. See if there is any change in PW; it might stay the same or maybe drop a bit (pressure going up will give more fuel for a given time period (PW) causing the more fuel to the cylinder and the fuel trim numbers to drop (richen mixture) If this doesn't happen -- back to the drawing board.

    Modifing the program to keep the check engine lite (MIL) off is not the way to make sure the system is operating within specified emission parameters; CAT damage can result.
    The add-on should be transparent and PCM not know the difference in fuels. Check the system with a 5 gas exhaust analyzer to make sure the tail pipe is showing correctly ( ball park; O2 should be around and CO should be around zero, CO2 around 10-11%, HC below 20ppm, and Nox 100 to 200 ppm, in loaded mode ) compare gas against cng CNG

    If conversion is giving problems It may not be the correct system for the vehicle or an EPA approved system

    Give it a try

    Larrycng
    Last edited by larrycng; 12-05-2011 at 12:42 PM.

  7. #7
    Join Date
    Dec 2011
    Location
    Edmond. Oklahoma
    Posts
    3

    Default Re: Doing a conversion on a Ram with 5.7 Hemi MDS Engine

    Update: My installer has everything up and running perfectly. Without much precedent to work with, he had to play phone tag with the system manufacturer IT support guys and spend significant time tuning everything. I don't know the specifics of what he did, but the truck now functions perfectly. No check engine lights, no stalling, and MDS functions normally.

    Serious props to Marvin of Marvin's CNG in Mustang, Oklahoma. It took awhile, but I've got exactly what I want.

  8. Default Re: Doing a conversion on a Ram with 5.7 Hemi MDS Engine

    Great news DRK. I am hoping to get mine wrapped up soon as well. Will report back when my issues get taken care of.

  9. Default Re: Doing a conversion on a Ram with 5.7 Hemi MDS Engine

    DRK, If you find out what was done I would be interested. I have a 5.7 MDS and would like to convert as well. I was concerned about the MDS issues as well. Thanks.

  10. Default Re: Doing a conversion on a Ram with 5.7 Hemi MDS Engine

    Quote Originally Posted by IronEagle View Post
    DRK, If you find out what was done I would be interested. I have a 5.7 MDS and would like to convert as well. I was concerned about the MDS issues as well. Thanks.

    What yr. Ram do you have IronEagle? 2011 & up are a hard nut to crack. Would I do it again? No,I would do something else. There's a kit for the 4.7 but the 5.7 is a whole other world.

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