MDS - fix it or turn it off

[jlsalani]

Recently my truck started to make what has been described as a ratcheting sound off throttle ECO light on, goes away in neutral and if selecting a gear or giving more throttle... did lots of research and based on when it happens and how I can get it to go away it is the MDS. I have 150,000 miles on my truck and still running great. Right now I set my gear+ to 8 everytime I drive and all is good. so the question is.. something obviously changed (or broke). Do I go and try to get it fixed? My understanding it is either the cam / timing chain / cam phaser(?) or the MDS solenoid(s)... I was not sure but it seems the solenoid failure would set a CEL, but wasn't certain. Not sure how much it would cost but have a feeling not cheap. I do a lot of my own mechanical work but have not really jumped into engine work. Haven't found a good local mechanic and really don't like heading to the dealership...

Other option is to just turn off the MDS with a tuner... lots of folks seem to do this, but my question here is did you hear the sound first and then turn it off or did you do it before?

let me know your thoughts

 

[2012RAM1500RT]

I'm assuming you didn't change exhaust to anything louder recently? I know when the MDS kicks in with any exhaust you can hear sounds terrible in my opinion. I turned mine off with a tuner a while back, don't miss it and don't have to fool with the gears anymore. That's what I did till I got the tuner. My only question is the reason you didn't hear it before if you changed nothing exhaust wise.

 

[jlsalani]

no change to the exhaust.... was just driving with my windows open next to a building and heard the sound for the first time

 

[Jeff Strader]

The 2019 and up do not have the ability with a tuner to turn off the MDS. The only way to turn off the MDS in the 2019 and up 5.7 Hemi's, is by replacing the ECM,ECU,PCM. On average a new ECM costs around $650.00....**However the moment you do that, you VOID your manufacturer warranty** So give it serious thought before you do, unless your filthy rich and don't care about no warranty.

 

[tones2SS]

The 2019 and up do not have the ability with a tuner to turn off the MDS. The only way to turn off the MDS in the 2019 and up 5.7 Hemi's, is by replacing the ECM,ECU,PCM.

It's the same for the 2015 and up as well, or 2016 and up, not sure which.
You have to replace the PCM and get a tune and you lose your warranty if you have one.

 

[Smokey613]

It's the same for the 2015 and up as well, or 2016 and up, not sure which.
You have to replace the PCM and get a tune and you lose your warranty if you have one.

The cut off is 2015+. I used my Diablo tuner I had for my 2011 300C for our 2014 RAM 1500. When we got the ‘18 I discovered the Diablo no longer worked without an unlocked PCM.

 

[tones2SS]

The cut off is 2015+. I used my Diablo tuner I had for my 2011 300C for our 2014 RAM 1500. When we got the ‘18 I discovered the Diablo no longer worked without an unlocked PCM.

Thanks for clarifying. I wasn't sure if it was the '15 or '16 model year.

 

[jlsalani]

what about the diablo pulsar?... piggy back to existing PCM?... it allows the MDS to be turned off... but no info on the question to fix it?... anyone do it and if so what might it cost?

 

[Pacman079]

I have the pulsar on my 16, I recommend it. It’s an easy removal if warranty work is a concern and it works well.

 

[jlsalani]

I have 150k miles on my 2015... no warranty issues here for sure!.. but still no one has brought their truck in with this issue to get fixed?

 

[HEMIMANN]

I have the Pulsar add-on PCM and at first turned MDS off. Then a member reported his Hemi valve ticking went away when he turned his MDS back on, leading some of us to think that MDS mode helps oil the lifter rollers (read about the engine oil MDS hydraulic circuit elsewhere).

So I leave MDS on now. No guarantees about anything, cause FCA (now Stellantis) clammed up and refuses to say anything about these failures.

 

[jlsalani]

so did he have it off for some time and then turn back on?... Maybe I will just keep that way for a little while and randomly check without the gear+ setup. doesn't sound ideal but what the heck.

 

[jlsalani]

I also went to redline oil and royal purple filter recently.... but put in the normal weight oil, have heard many use a different weight to help with the sound.

 

[runamuck]

I use the recommended wt. Mobil 1 and no tick with my 5.7. I am only at 21000 miles though but about 6000 of that is towing a 6000# travel trailer. all good so far

 

[RLJ10X]

Doesn’t sound like a cam smacking a lifter, does it?

If it makes racket when the MDS is in, and doesn’t when it’s off, turn it off.

$600 or hit a button when you get going? Hit the button. It’s an imperfect world.