questions about mds engagement with eagle 5.7

[robryche]

One thing I've noticed with mine, is that when going from light throttle cruising, to medium throttle, the engine seems to try to stay in mds even with increased load, and sounds like it's lugging and then i get some drone through my exhaust ( non-stock).

Is this normal for the newer engines? I had an '07 RT prior to this vehicle, and it seemed like there was no hesitation coming out of mds under a mild throttle load.

If it is normal, is there something in the tune besides the throttle adjustment in the diablo tunes, that can be adjusted to eliminate this?

Thanks

Rob

[Montreal300]

The original software in my 06 was pretty sensitive to throttle position and would come off of MDS really early. A software update that I installed 3 years ago has a much more agressive MDS schedule and I'm having the same experience as you are. At low speeds in traffic I dump it into autostick (4th) to give me some peace.

[robryche]

Montreal, what sort of update? one required by using a predator tune or a dealer flash? That's one thing I miss about my '07, was how smooth it was. Anyhow, I've noticed something that may help both of us in this regard on the diablosport forums. It seems like people are having their tunes adjusted to smooth out mds transition. Think I might give it a try.

Rob

[Montreal300]

When I bought my Predator three years ago and logged it to the Diablo site, I got a notice that the OEM software needed to be updated before I could use the Predator. As far as smoothing it out, it would be nice but when highway cruising I have noticed a difference in fuel economy so I'm willing to live with it for now. 26 mpg is pretty good.

[Daphod74]

I have an '05 and the dealer also did a PCM software update around the '07-'08 timeframe. I noticed some changes in MDS behavior afterwards - specifically it was a bit more noticeable and would load the engine more in 4cyl mode before kicking back into 8 cyl mode whereas it was undetectable when new. After adding a Predator tune, TB, CAI and cat-back, it's MUCH more noticeable. My theory is that the engine is making a bit more power than the program is expecting and feels that it doesn't need to switch out of 4 cyl mode as readily - whether it's because of electronic torque sensing or vacuum activation, I don't know.

I'm guessing with your exhaust and intake mods, it was enough to make the MDS activation/deactivation noticeable just like it did for me. I'm considering getting the MDS smoothing done by Diablosport, but at the same time I'm considering a heads/cam install so I might just wait...

[robryche]

Daphod, if you get the smoothing done before i do, can you please post how it is in here? Also, yes, mine was noticeable with even just a corsa cat-back, almost acted/sounded like mild pinging. With the solo exhaust and cats, well, i tried a canned tune for a bit, and now run a tune without mds right now.

[Daphod74]

Daphod, if you get the smoothing done before i do, can you please post how it is in here? Also, yes, mine was noticeable with even just a corsa cat-back, almost acted/sounded like mild pinging. With the solo exhaust and cats, well, i tried a canned tune for a bit, and now run a tune without mds right now.

Sure - I'll try to post the before/after results when I get the tune adjustments. Mine felt like the torque converter clutch was acting up kind of a clunk when applying and releasing the throttle very lightly like when you're maintaining speeds of 45-55MPH in light traffic. I had the tranny fluid changed and I decided to turn of MDS to reduce the number of variables - sure enough the clunk went away. I have MDS back on and now with the cat back I can hear 4 cyl mode a bit more easily (plus I think it stays in 4 cyl mode even longer).

[robryche]

Update:

Since original post, I have gotten an email tune from Johan (diablotoona), I still have to do some datalogs for him, but the overall drivability is vastly improved. Light to mid throttle, engine no longer hangs up trying to stay in mds, and the transition is smooth coming on and going off. I'll update more later.

Rob

[Daphod74]

Update:

Since original post, I have gotten an email tune from Johan (diablotoona), I still have to do some datalogs for him, but the overall drivability is vastly improved. Light to mid throttle, engine no longer hangs up trying to stay in mds, and the transition is smooth coming on and going off. I'll update more later.

Rob

Excellent news - thanks for posting that. I emailed him yesterday and am thinking about it, too.

[Mikystyle]

At low speeds in traffic I dump it into autostick (4th) to give me some peace.

I do this same thing on my 2010. Best solution and with an aftermarket exhaust it sounds much better than the buzzing from the mds under load.

[robryche]

I would do that as well, until i had mds shut off in the tune. I figured since it's on the motor, do some road-trips every so often, I might as well try and get it more user friendly. I look at it as, I'm getting srt mileage, without all of the srt power. lol
Too simplistic? maybe.

Anyway, started data-logging for Johan. Serial cable to USB issues not withstanding. Initial drive-ability seems a lot better compared to previous tune. More smooth going into and coming out of mds, and the mds sound seems more tolerable.

Will update later.

Rob