mds pulse

[crazylikeacharger]

one thing i have noticed on the way to work is i set the cruise and when the car needs to make more power than the 4 cylinders make it kinda pulses forward a little when all 8 cylinders start working. whats causing this

[christina]

Perhaps when the car is switching over while under cruise it pulses while activcating the other 4 cylinders? There is an option to disable the MDS in the Predator.

[crazylikeacharger]

i want to keep my mds on since this is a daily driver and keeping that gas milage up its my top priority. its not that noticable, i dont think anyone not knowing about it will notice. thanks

[plcman]

My car does the same thing surges when in MDS flat highway any mph. This is very troubling to me.
What is going on?

[KWhale]

I had this issue as well. When driving on roads that had some rolling hills, I noticed it would actually down shift when it came out of MDS, in order to maintain the correct cruise speed. When I turn off the Firmer Shift option, in other words, just take the settings that come with the tuner, and do not install firmer shifting, it no longer has that surge in it.
I figure for the winter, I will just live without the firmer shift setting, and hopefully by next May, they'll have a solution to that problem.

[KWhale]

Well, it seems I lied in my above post. Even with NO Firmer Shifting selected on the 91 CAI tune, on my 06 300C, I am still getting some surging still. I can tell by the faint change in the exhaust note when MDS turns off and I'm running on all 8 again, and the car seems to pick up about 200 RPMs, almost like a down shift, then back to where it was again. The whole thing only last about 1 second, but it is definitely happening even without the Firmer Shift settings (ie only setting is what the 91 CAI comes with as far as shifting).

Mike - I have seen several complaints about this surging on the boards. I do not want to turn MDS off, as the car travels about 100kms every day, and about 80% of that mileage is on the highway where the MDS does it's best work. Is Diablo looking into this or is this a matter of "that's just the way it is, live with it" ????? Please let us know either way ????

[crazylikeacharger]

Anyone ever try shutting off MDS to see how much gas you really save with it on????

[mikel]

Guys, MDS is a whiz-bang marketing gimmick from Chrysler, much like GMs DOD or AFM....we have seen time and time again that we can get better mileage out of a car by disabling these devices and tuning properly than they ever did stock.

My guess is that the increased throttle response is making it more sensitive, have any of you tried using cruise control to see if it goes on/off less?

Thanks

[claude9039u]

Yes I drive all my miles on the highway 100 a day on cruise and it does ot inone stop. Kind of tired of it to tell you the trut h. Any idea's other than turning off MSD. I will try it and see if I get a change in Gas milage. I have CAI 2 1/2 exhaust and I have never seen at crusie 70 any more than 20.8 MPG.

[inrandy39]

I do not notice any difference in the feel of the MDS after my 93CAI tune. I have always noticed it because when MDS is active(4 cylinder mode) the torque converter is slightly slipping and when the MDS kicks off the converter locks-surges slightly. I am thinking of turning off the MDS for a few weeks to see how much this really affects my mileage.
Randy

[mikel]

Go for it, and let us know how your mileage ends up.

Thanks

[rotrhed]

Add me to the list...
Just installed the 91/CAI tune on my 300C, and while I appreciate the performance improvement, I am not at all happy with the surge impact on my daily driving
It's definately there at about 60 on cruise or not and also at about 30-35 with light foot on the pedal going through the small towns on my commute.
I drive 100 miles a day highway to/from work, and this is NOT the way I want my car to drive. It's way irritating!!!
I'd like to see someone's results with MDS off, but I don't like the answer that it's the MDS' fault. There should be a fix from Diablo via an update.
Just my opinion as a not too satisfied customer...

[workhorse]

I have to agree with Mike about MDS being mostly a marketing gimmick in response to other manufacturers. I am not an expert nor do I have a degree in automotive engineering, but I would attest to 2 things on this topic with a high degree of certainty -

1) MDS plays a key role in the pulsing behavior. I bought my used stock 2006 Charger in July this year and began modifying it immediately. Mopar CAI and Borla high-flow exhaust went on almost immediately. The pulsing became every so slightly noticeable while cruising at 80MPH (foot on throttle or not). Superchips Flashpaq came soon after and it became a little more noticeable and more frequent. I also tried Jet Stage II for a day or so (just didn't like it!). SuperMaxx ceramic coated long tube headers came next and then the pulsing became down right irritating no matter what the driving conditions. Diablo Predator finally ships and I go for the most aggressive tune available (Performance CAI - 93 octane). This tune initial impressed me with how much it improved the overall driving experience while also bumping the power noticeably, although not significantly compared to what I was already experiencing with Superchips. However, the MDS pulse became almost unbearable at this point(no doubt due to the improved throttle response!). A few weeks ago I upgraded to r16, installed latest tune with MDS disabled and WOW!!!! The car is soooo smooth and soooo much fun to drive now! I considered my car to be so sloppy before this tune to the point I was starting to regret my purchase and began looking at Mustangs again. Now it drives as smooth as most any performance/sports car I've ever driven with the exception of the suspension and braking. (for what it's worth I've owned a lot of sports cars and usually heavily modded, not to mention quite a few laps in a Winston Cup car for the Richard Petty Driving Experience)

2) MDS does not provide any significant mileage gain when combined with the performance tunes that the predator provides. I live in a suburb 60 miles outside of Atlanta and drive into the city everyday. (120 miles roundtrip) With the early 93 tunes that came with the predator I actually tracked a slight improvement. These did not have the MDS disable feature, but I can tell you that it was kicking in and out so much that there is no way it was effective. Since then my mileage has been up and down as much as 5mpg on average per tank. With r16 and running with MDS disabled for 3-4 weeks now the trend hasn't changed at all, but the performance and drivability sure has. It's also important to note that the cold weather has crept into the area during the past 6 weeks or so which has also contributed to some power gains and probably a heavier foot. I think there are just too many variables that impact fuel mileage, and I really don't believe that you could attribute the best case claim of a 20% improvement entirely to MDS anyway(stock tune in a controlled environment no doubt, btw). Bottom line is that this topic is largely subjective.

Again, I'm no guru, I'm just an enthusiast. I don't put my car on a dyno or strive for empirical proof with respect to mileage or power gains. I go on what the car feels like and what comes out of my wallet, since that's ultimately what's important to me. Also, my apologies for the lengthy post, it was not intentional.

[KWhale]

Thanks to everyone for relaying their own experiences with this. I personally do not want to disable MDS. My fuel bills for the year are already over $6,000 and while 10% might not mean much to the average driver, every 10% means $600 to me. The same questions remain unanswered:

Mike:
Can Diablo eliminate this annoying MDS surge?
IF so, Are they actually working on it?

Looking forward to seeing the answers.

[KWhale]

Bump for Mike to answer maybe????