Posted by on 25th February 2020

Service guide for the Mopar HEMI Multi Displacement System Jeep, Chrysler, Dodge & Ram

How the MDS problems started

Here we investigate my own Jeep HEMI Multi Displacement experiences with a pre-VVT 2005 Jeep 5.7 MDS Hemi engine. At 70,000 miles, one of the MDS solenoids stopped working (there are 4 on this engine), the Mopar HEMI Multi Displacement System or MDS.

The resulting symptoms where the engine would not go back to 8-cylinder mode, it stayed in 4-cylinder mode resulting in terribly rough running. Only cutting the engine and restarting cured this. The video below shows how I deal with MDS on a daily basis. It took a long time to figure out the system.

 

What is MDS?

An electronic solenoid driven system triggered by engine load data from HEMI engine’s computer. During an MDS activation, HEMI cylinders 1, 4, 6, and 7 are shut down in order, with one cylinder being deactivated every 180 degrees of crankshaft rotation, leaving cylinders 2, 3, 7 and 8 to drive the engine. This is supposed to deliver 15 to 20% fuel savings by making your 5.7 Liter engine a 2.85 Liter engine. It can work, but as with alot of technology, you need to service the system or it will break.

Living with the MDS problems

This is a major engine repair so you can manage the situation as I did for 6 years and 50,000 miles by just locking the Mopar HEMI Multi Displacement System or MDS off. There are 2 simple ways to do this. 1. Manually shift from D to 4 while driving. 2. Press the Tow/Haul button so the light comes on.

Sometimes I forgot to do this and got caught out with a repeat performance of non 8 cylinders running, resulting in me having to stop the engine and restart it. (Not a good idea on the UK’s new “Not so Smart Motorways”) or long tunnels.

If you have an eco-light fitted, it will tell you that you are running on 4 cylinders, but as the one MDS solenoid not working plays havoc with the whole system and delays the 8-cylinder reactivation, no frantic pressing of the Tow/haul button will fix this on a run. You cannot use the Tow/haul button or shift out of top gear 5th to 4th to switch back into 8 cylinder running mode when this failure occurs. I know I’ve tried! Just pull over.

 

The endgame and getting it properly fixed

Diagnose the fault properly before you go any further. I used the economy diagnostic tool the OBD2 JScan app and caught the error code one day while the terribly rough running was happening. OBD Error Code: P1414 Definition: Cylinder 4 reactivation control performance failure. That confirmed which MDS solenoid had failed. This is in Bank 2 of the engine. Also watch out for P3497 Cylinder Deactivation System Bank 2 error code. So I watched YouTube and saw Dorman Solenoids were a possible solution.

The codes thrown on my Jeep before repairs

  • Code P0300 Random or Multiple Cylinder Misfire Detected
  • Code P3497 Cylinder Deactivation System Bank 2
  • Code P1414 (Cylinder 4) Reactivation Control Performance

 

Pushing the Parts Cannon Button

You will eventually need to get your just empty every pocket Jeep wallet out and buy some new parts. Or with Rockauto your PayPal will do the same. Its not that expensive to fix the Mopar HEMI Multi Displacement System or MDS. Buy all 4 Solenoids. This is also a good time to do an engine oil flush to clean all the oil debris inside your engine after 100,000 miles.

What parts to buy

Mopar part number 53032152AD are fine. They cost around $100 US each. You will need a new intake gasket set. If you drive a 2005 model, get new set of ignition leads, also do all of your injector seals or o rings, replace any plastic parts that have gone brittle. The time to do this is now as you are stripping down quite a bit of the engine. Also do an oil service. Future proof the car or truck.

Mopar HEMI Multi Displacement System or MDS. Old HEMI MDS Solenoid has been extracted like a broken tooth

Old HEMI MDS Solenoid has been extracted like a broken tooth, The one at Cylinder 4 was full of oil

 

Mopar HEMI Multi Displacement System or MDS. Jeep 2005 HEMI Ignition Leads are well and truly cooked after 120,000 miles

Jeep 2005 HEMI Ignition Leads are well and truly cooked after 120,000 miles

 

Jeep HEMI Multi Displacement System or MDS. Mark 3 HEMI MDS Solenoids in the engine block

Mark 3 HEMI MDS Solenoids in the engine block

 

Mopar HEMI Multi Displacement System or MDS. HEMI plastic parts will have gone brittle after 10 years so replace all you can

HEMI plastic parts will have gone brittle after 10 years so replace all you can

What not to do 

After I’d had the repair done I suddenly got loads of new MDS error codes.

  1. P3400 Cylinder Deactivation System Bank 1
  2. P1411 Cylinder 1 Reactivation Performance
  3. P0301 Cylinder 1 Misfire Detected
  4. P0300 Random Multiple Cylinder Misfire Detected

So lesson learned here, do not buy Dorman part number 916511XD. It may be tempting as they are $45 or so, plus there are YouTube videos that tell you they’ll be fine. The photo below shows a Dorman MDS Solenoid after 500 miles. Basically clogged up. They have a severe lack of magnetism, which is the whole point of a solenoid’s function, to turn on and off. The result was a half open solenoid that stopped cylinder 1 from even firing. So only 7 cylinders on a V8…

So basically I had the same job done twice and that was completely unnecessary. Maybe I should have done the engine oil flush before changing to MDS Solenoids out?

Jeep HEMI Multi Displacement System or MDS. Dorman part number 916511XD

When this happens you think the worst as the engine runs so badly for a Jeep HEMI Multi Displacement System or MDS

Misfires, rough running, erractic MDS function, error codes. Stories on YouTube of broken lifters, broken rocker arms, worn and gouged camshaft lobes, lack of vacuum on the intake, leaking gaskets, cracked heads. A mechanics dream of stripdowns. We had the rocker cover off to check for the worst, there was nothing but a clean engine.

Mopar HEMI Multi Displacement System or MDS. Dorman part number 916511XD causes issues

Buy genuine Mopar parts and save loads of money in the long run for Jeep HEMI Multi Displacement System or MDS

That’s the story folks, spend the extra $200 on spare parts, or you’ll be off-road in a bad way for weeks on end! Plus you’ll pay a lot more than you bargained for with double repair bills.

Mopar HEMI Multi Displacement System or MDS. Dorman part number 916511XD caused me grief beyond belief

MDS Update from March 2023

After all this MDS faffing around trying to make the system work, I gave up. I had it disabled and the Jeep has never run better. MPG has hardly changed. Why use this system still if it causes so many problems? If you really want to save money by fuel consumption in a HEMI, then drive a bit slower and keep cruise control on a bit more and save money that way. No more hesitation from technology that is unnecessary. Plus MDS can crack your block due to uneven heating and cooling, a whole other story!

But then my service mechanic fiddled and managed to cancel the MDS disable code that my engine tune had put in place and then could not reset the MDS as I wanted it to be… OFF. At this point I gave up. Cutting to the chase, on Petrol (or Gas in North America) MDS is fine. On LPG (Autogas which is Propane 95% and Butane 5% blend), it makes the 4 cylinder running cycle a strain as the LPG has less power to offer. So use the gearbox to select one gear lower than the highest to disable MDS on LPG and you’ll be fine. Or use Tow/Haul. If you are driving at 80 mph on the flat the MDS won’t even try to engage, so you can use the highest gears on automatic gearbox still, but downshift manually when slowing, coasting or on a hill.

Summary

I’m happy with the MDS system now its been repaired, it saves fuel and does not cause any problems. Plus if I want it off, I can do that switch very easily, as my videos explain.

 

 

Comments

Be the first to comment.

Leave a Reply

What I offer in my shop. Repair kits and T'shirts. If you’re a long suffering; buddy, brother, sister, friend, wife, girlfriend, husband, boyfriend, father, uncle, aunt, grandparent, or mother, of a car nut, be it classic muscle car, Jeep 4x4, or off-road truck driver, the above link is the place to get them something nice and long lasting, for their; birthday, anniversary or Christmas! Without costing you too much money.

Laurence Dunn

Lozs Cool Rides T shirts last for years and 100s of washes, they still look good thanks to high quality Silk Screen Printing. My 45 years of professional Print experience helps!

Videos

Extreme Jeep Wrangler Off-Roading in Chambon FRANCE

How to disable MDS Mopar HEMI Multi-Displacement-System on Jeep, Chrysler, Dodge & Ram without tuner

WK Heated Seat Button Repair, Jeep Grand Cherokee 2005

How to fit low cost Fender Flares on WK WH Jeep Grand Cherokee 2005 2006 2007 2008 2009 2010 years

K&N Cold Air Intake + Magnaflow

WK XK Information Center

Repair leather seat Jeep 2005 WK

WK WH headlight assembly

ORT graphic Grand Cherokee 2005 2006 2007 2008 2009 2010 WK

Mustang GT MUFFLER DELETE Review with Pypes long tube headers, cat-back X-pipe & Pypes bombs in full

Mustang Owners Club Nationals 2022

Long Tube Headers X-pipe & Pypes Bombs idle launch & warm start Ford Mustang GT/CS 2007 4.6, Part 1

Which MDS Solenoid is best for my HEMI engine?

Mustang drive local and big roads

Ace Cafe London Mustang Day September 2023

Southend City seafront drive back