Odd Surging

[jongohr]

Car: 2009 Dodge Challenger R/T Auto, AEM Brute Force CAI, Pypes Catback with Violator mufflers, Modern Muscle 85mm ported throttle body, BT Catch Can.

Filled the car today with a full tank of Amoco Ultimate 93 octane and then installed the 91 octane cai tune. This was my first time installing a tune on anything and it went very smoothly.

In manual mode the car is a beast, got rubber on the 1-2 and 2-3 shift. Was really impressed.

In automatic mode and cruising at any speed the car will surge oddly and seems to not know what gear it wants to be in. Should I reset adaptives? Disable MDS (Can we do that)? Data log and send to a good tuner?

Any advice will be appreciated.

[Mike_Levy]

Its probably the TB. Did you have the blade calibrated with a StarScan?

[Quick]

Try disabling the MDS before looking further. When cruising it kicks in and out. The tunes reduce torque management and then you can feel the MDS switch.

Go to the perf tunes section, select the tune, then go into modify parameters... then you just have to find the MDS parameter and turn it off (I have no idea which sub menu it's under). Menu out and install the tune.

[jongohr]

I've had the throttle body on for over month prior to installing a tune. So my guess, from reading other similar threads, is that this is a MDS related issue. Will modify the tune when I get a chance and see what happens. Thanks.

[Nickrt]

Have read elsewhere that the Diablo team can modify your program so that the MDS still works but without the surge. May want to check in with them before you disable.

[jongohr]

Have read elsewhere that the Diablo team can modify your program so that the MDS still works but without the surge. May want to check in with them before you disable.

Thanks for that info ... if that is indeed the case I'd love to get that tune. Anyone from DS have any input?

Thanks!

[jongohr]

Not sure if anyone from DS has read or is following this thread?

Drove the car 40 miles today and have to say it's virtually undrivable in automatic mode. The surge cruising at 55 to 60 mph in automatic mode is terrible. I would even say it feels unsafe.

I've only been able to try the 91 octane CAI tune. The best gas in my immediate area is 93 octane Amoco Ultimate at a BP a good distance from home. Everyone else only has 91 or 92. I have serious doubts whether the BP 93 is good enough for the 93 octane tune.

So is MDS off the only solution or is there a better tune available for the automatic cars with the U7135 and 9r17?

[brandy16]

Turn the MDS off. and see if it stops surging. My car a 2006 300c did the same thing. I had to turn the MDS off. The tune will give you better fule milage so if you turn off the MDS you should be getting the same or close to the mielage you got without the tune and the MDS on. Give it a try and see.

[fireman2118]

I had surging in my car (R/T) until I turned the MDS off.

[06MonteSS]

yeah, it's your MDS system.. disable it...

the same thing happens with GM's DOD/AFM...

so either disable it, or ask the diablo guys if they'll make you a custom tune to fix it.. it is doable via a custom tune, cuz I've done it for other GM users and our DOD/AFM system...

[CaptainJ]

I have MDS off and it still surged for about 4 weeks after a new tune until the computer re learned what was going on. (I guess) At any rate my car always settled down after a few week after re-flashing.

[jongohr]

Thanks for all the info everyone!

I restored the stock tune this morning for the drive to work. Miss the snap of the tune but not the surge.

I'll modify the tune and turn off MDS as soon as I have time and see if I like it. Probably after the first oil change which is coming up pretty quick.

[smssupercars]

Let us know when you try it!

[jongohr]

Modified the tune and disabled the MDS. That does appear to fix the surging problem.

[rham48]

Mine is doing the same thing (surging) while cruising on the freeway. I'll try turning off MDS, thanks for the tip! Russ