how does the MDS on a Ram 1500 with a 5.7 Hemi work?


Asked by Nov 26, 2014 at 01:19 PM about the 2007 Dodge Ram 1500 SLT Quad Cab 4WD

Question type: Maintenance & Repair

Had my motor rebuilt, and it was running great I took it to a dealer just to have it checked out and was told I had a bad coil pack, they replaced it and when I was driving home the truck developed a miss so I took it back to the dealer now they tell me they did a leak down test and I have a bad cylinder . I was wondering if the mds can have something to do with the miss?

3 Answers


mds works by closing all the valves to a cylinder and shutting off the fuel to it as well. if they did a leakdown test, you will have to ask them what they mean by bad cylinder. It could be rings, or either intake or exhaust valves, there is even a possibility of a head gasket failure. I am guessing that they think it is rings. if you recently had a rebuild, it is possible that they didn't seat in that cyl. I am sorry that I dont know for sure how mds is tested, but I would guess that the dealer would do some kind of a Live data scan while driving. hope this helps.


The dealer told me it could be the rings or I spun a valve. I never heard the term spun valve, I thought the valves turn, that's why you seat your valves. .At an idle it feels like I have a miss, but when I accelerate it runs fine until I hit about 50 mph then I get a hard vibration out of the motor. When I hit the passing gear it starts to go like a bat out of hell then I lose power


I think its time to take it back wherever it got rebuilt. bummer. hope it is under warranty. btw, i have never heard of a spun valve either. spun bearing, but not valve. oh well. live and learn. sounds expensive. really sorry.

Your Answer

Add photo

Related Questions

  • Dodge ram hemi swap 1 answer

    I have a 2004 5.7 hemi ,that needs an engine,found one from a 2005 durango,will it work since its not mds?

    2004 Dodge Ram 1500 SLT SB


    Maintenance & Repair

  • Will a 2006 5.7 hemi work in 2005 1500 truck 2 answers

    2005 motor blown

    2005 Dodge Ram 1500


    Maintenance & Repair

  • 2007 dodge ram 1500 hemi 5.7 liter please help 2 answers

    My dodge ram 1500 5.7 liter hemi is over heating & hot air on idle there enough coolant please help on what else it can be ?

    2007 Dodge Ram 1500 Sport


    Maintenance & Repair

  • Ram 1500 3009 hemi engine does not start 2 answers

    I got a ram 1500 2009 big horn wth a 5.7 hemi. Car wont start. It is not the battery. We jumped cable and did not start. What could it be ?

    2009 Dodge Ram 1500 Laramie Crew Cab


    Maintenance & Repair

  • Hemi MDS 227 answers

    I was wondering if anyone other than me absolutely hates the MDS system in their Hemi engines. Does anyone know how to disable it without having to by a Diablo Predator tuner? I know you can cut and c...

    Dodge Ram 1500


    Car Customization

Ram 1500

Looking for a Used Ram 1500 in your area?

CarGurus has 13,734 nationwide Ram 1500 listings starting at $995.


Search Dodge Ram 1500 Questions

Dodge Ram 1500 Experts

#1 Dan Connell
Dan Connell
Reputation 5,280
#2 pudgybear
Reputation 5,000
#3 dandyoun
Reputation 4,670
View All

Related Models For Sale

Used Ford F-150"
3,257 Great Deals out of 216,652 listings starting at $1,500
Used Chevrolet Silverado 1500"
2,440 Great Deals out of 144,713 listings starting at $1,995
Used Dodge Ram 2500"
154 Great Deals out of 5,744 listings starting at $2,289
Used GMC Sierra 1500"
1,026 Great Deals out of 56,923 listings starting at $2,300
Used Toyota Tundra"
619 Great Deals out of 26,773 listings starting at $2,500
Used Toyota Tacoma"
618 Great Deals out of 30,503 listings starting at $2,850
Used Dodge Charger"
640 Great Deals out of 29,672 listings starting at $2,275
Used Dodge Dakota"
161 Great Deals out of 4,799 listings starting at $900
Used Ford F-250 Super Duty"
440 Great Deals out of 42,987 listings starting at $2,250
Used Nissan Titan"
225 Great Deals out of 13,314 listings starting at $4,500
Used Dodge Challenger"
439 Great Deals out of 25,365 listings starting at $7,980
Used Dodge Ram 3500"
103 Great Deals out of 2,511 listings starting at $4,995
Used Ford Mustang"
725 Great Deals out of 41,064 listings starting at $900
Used Jeep Wrangler"
461 Great Deals out of 16,415 listings starting at $3,400

Used Cars For Sale

2010 Dodge Ram 1500 SLT Quad Cab 4WD For Sale
12 Great Deals out of 246 listings starting at $9,995
2009 Dodge Ram 1500 SLT Quad Cab 4WD For Sale
6 Great Deals out of 219 listings starting at $5,999
2008 Dodge Ram 1500 SLT Quad Cab 4WD For Sale
15 Great Deals out of 355 listings starting at $8,500
2007 Dodge Ram 1500 SLT Quad Cab 4WD For Sale
18 Great Deals out of 434 listings starting at $5,995