Why does my 06 1500 4x4 truck with 56k on it switch in and out of MDS literally every other second on the highway between 55-70 MPH with cruise on? it is worrying me because it has already caused 900 bucks of transmission issues. the shift solenoid went out.

bad sensor? No codes have popped. i turned MDS off with my tuner and everything runs smooth. I don't want to keep it this way because of the gas prices now. i would love to get MDS back but not at the expense of blowing up my transmission.

THis is driving me nuts.

My suspicion is the crappy exhaust system that the previous owner had put on it. is messing with the PCM or TCM.

Any help would be greatly appreciated.

thanks

 

Mine did that too at speeds over 55mph. I don't think that it makes enough power in 4cyl mode to overcome the wind resistance, so as the cruise fights to keep the mph steady, the moving of the throttle by the cruise causes the MDs to kick in and out. I haven't noticed a decline in mpg with it off. It is actually $1.26 a tank full cheaper to run the 93 octane tune and fuel than to run the stock tune and cheap gas. I leave my MDS off.

 

i have the 93 OCT tune as well. just started using it so we will see what the difference is.

MDS is off for good then. how stupid was Dodge for putting that on a truck weighing so much. Seems like when Mercedes was running Dodge, they did some really good things and some really dumb things.

 

Nobody has gotten it right with full size trucks yet. Good buddy of mine has a Cheby 4x4 with the 5.3 V8 with cylinder de-activation and it does the same damn thing and he says everybody on the GM truck forums bi*ch about it too.

Cylinder de-activation on heavy trucks and SUVs is just something to make the Govt. EPA boys happy...

 

I cam back you up on that. I had a 2007 Silverado( new body style )with the 5.3L and AFM( Active Fuel Management - same as MDS )and it did NOTHING for MPG and actually for me it gave worse MPG than my 05 Silverado with 5.3L and no AFM. Both were EC 1500 4WD trucks.

Same has happened with my Ram's and MDS. Had an 04 HEMI w/o MDS and now an 08 HEMI w/ MDS and the 04 got better MPG. Both QC 4WD 1500's.

Now with that said it is possible the MPG might be approx the same between the 2 in each case. The reason being the 04 Ram and 05 Silverado were run exclusively or almost exclusively on 100% gas. I had the 05 Silverado on the road only a short time after 10% ethanol showed up here in our fuel before going to the 07.

I certainly can say in my experience anwyay at the least AFM/MDS have not "increased" MPG as the mfg's claim it will. It appears it is worse but due to the E10 I have to run it may be the same.

Not impressed with it anyway.

 

Unless this is happening on flat roads with no wind it sounds like normal MDS operation to me. MDS only activates and stays on under low load/RPM conditions. If the truck can not maintain speed due to inclines and wind resistance it will deactivate MDS. It will also go off more, or not even come on, as you go faster( 70+ )due to an increase in load. I use CC and set it at 60 MPH and MDS stays on unless I hit inclines and wind.

Question for you. You are running a 20 weight oil correct? You have 0W-20 or 5W-20 in there right? If you have a 30 or 40 weight oil you need to get a 20 weight in there as MDS uses the oil to help operate the system. It MUST have a 20 weight oil to operate properly. Another member on here recently had issues with their MDS not working properly due to a collapsed filter media in a cheap Fram filter. It resitricted oil flow and pressure so the MDS system did not operate properly. What type of oil filter are you running and are you near or due for a change?

 

Keep in mind that with an exhaust modification, the MDS is easily heard when it kicks in and out. Before I had my Magnaflow muffler installed, I could barely notice the MDS in action because the truck was super quiet. Now it is very obvious when it kicks in.

Thanks for the information on the 20 weight oil. I have always used it but never really knew the logic behind it.

 

I should have asked if the exhaust mod was still in place on your truck. If it is, have you experienced MDS on a Ram with stock exhaust? Many of us have experienced the MDS both ways, and it is very obvious in action with an exhaust mod, especially an agressive exhaust system. So, it may not be kicking in and out excessively at all.

 

I just changed the oil and filter to Mobile 1 full synthetic 5W-20. i just bought the vehicle from the dealer about a 2 months ago. it was at a chrysler dealership so i assumed they put the right oil in it, but changed it any way to be sure. we have a 06 Magnum R/T with MDS and it runs differently. So i have some experience with these new hemis. we have had the magnum since it was new in 06. i understand it is a can and this a 4x4 truck and it will run differently.

My main concern is the frequency at which it goes in and out. if it's a flay strectch of highway then it will never settle into MDS. it constantly switches in and out. when i get down hill it stays on and when i get on a slight incline it switches off no problem. seems to work as advertised.

It's that constant on/off that is wearing on my transmission. it already caused me to have to change the shift solenoid. after only 1000 miles after i bought it.

Question for you guy, when your MDS turns on, what happens on the RPMs? mine climbs about 200rpm and when tries to drop 300 as the converter tries to lock up. it locks up for about a second and then the MDS turns off. I can hear it in the exhaust, you are right, but it more pronounced in the shifting and the way it makes the tranny go "clunk" that bothers me. the exhaust is a crappy flowmaster one that looks like it was put together by a high school tech class.

Could this be a bad converter?

I turned the MDS off and the converter locks up fine. that's the way i have been driving it for a few days now and no lights. i rest the PCM and TCM too. no codes.

 

Like others, I seriously question if there is any benefit whatsoever to the MDS in my Ram. I drive 40 miles a day round trip on the expressway to my job, 5 days a week, and the best my mileage estimator ever shows is mid 15mpg. My previous vehicle was an 05 Durango, no MDS, and it was comparable. Seems like more trouble than it is worth. I thought an exhaust mod would improve things a bit, but I have seen no notable difference. Same goes for my tonneau cover.