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Discussion Starter · #1 ·
:confused:ok i will start off saying i am a mechanic and try to do most work myself(ok im cheap too).. i have worked on a few magnums and chargers before i bought mine so i know just enough to get me in trouble.
here is what i have my hemi has a slight miss at idle and when you accelerate it goes away and stays away aslong as you are on the throttle, but it gets worst when i get up to about 50-70 i have flowmasters so it actually sounds like a jake brake on a big rig when im cruising along its like a couple cylinders cut out . but i can tap the gas and they kick back in and run fine until i get to cruising again. i had a charger that did the same thing a few months ago that i was working on and i changed the esp abs unit and it went away i think (guy never brought it back) but my abs unit looks fine and abs light isnt on but my esp bas light is on because i bought car wrecked and it has a bent tie rod end and steering wheel is off a hair. now my question is can it be from the steering being off and the esp ? i thought if the esp light was on it meant it was disabled? i have a snap on modis and have checked the codes and nothing out of the ordinary is in there but
in the wreck nothing was hit hard enough to break anything on motor etc but i did the throttle calib. and it seems worst now . so could it be im doing it wrong ? anyone have any clues or what to check next?
 

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When your cruising along a couple of cylinders do cut out,4 actually.....it's called MDS(Multiple Displacement System) and it's there to give you better mileage.The flowmasters will make the car sound horrible in MDS mode.The slight miss you feel on the bottom is probably the normal skip most Hemis have.
Not to be a smart ass but I would recommend starting with the owners manual.
 

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Discussion Starter · #3 ·
When your cruising along a couple of cylinders do cut out,4 actually.....it's called MDS(Multiple Displacement System) and it's there to give you better mileage.The flowmasters will make the car sound horrible in MDS mode.The slight miss you feel on the bottom is probably the normal skip most Hemis have.
Not to be a smart ass but I would recommend starting with the owners manual.
i have actually been browsing through it, lol
ok i understand the concept of MDS but why did it stop on the other charger i worked on? maybe quit working? i also drove a hemi magnum for a few days and didnt notice the MDS kicking in and out at all on the highway . is there anyway to disable it i can do without the fuel savings over the hum of exhaust .
 

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i have actually been browsing through it, lol
ok i understand the concept of MDS but why did it stop on the other charger i worked on? maybe quit working? i also drove a hemi magnum for a few days and didnt notice the MDS kicking in and out at all on the highway . is there anyway to disable it i can do without the fuel savings over the hum of exhaust .
Did the other hemi cars you worked on have the stock exhaust? With the stock exhaust, the change in sound is very subtle when mds kicks in (the oem exhaust is designed to make it practically undetectable). You can disable mds with a Diablo Predator. I have a JBA exhaust and keep mds disabled because I can only imagine how horrible it would sound with mds engaged.
 

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Discussion Starter · #5 ·
Did the other hemi cars you worked on have the stock exhaust? With the stock exhaust, the change in sound is very subtle when mds kicks in (the oem exhaust is designed to make it practically undetectable). You can disable mds with a Diablo Predator. I have a JBA exhaust and keep mds disabled because I can only imagine how horrible it would sound with mds engaged.
actually yeah the magnum was stock, the charger had cat back magnaflow, and i believe the guy used the predator when he got it back , so maybe thats why he never brought it back with same problem...see im learning more and more everday lol
 

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Discussion Starter · #7 ·
i just found a diablo predator on craigslist for 250 , meeting guy tomorrow to pick it up :rocker:

thanks for the help :bigthumb:
 

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Another way to tell if it is coralated with mds is to check evic. Scroll through your options to mpg, it will show when you are in fuel saver (mds) mode. It will definately sound different with aftermarket exhaust...search for exhaust drone. Using Auto stick in 1-5 will negate mds kicking in. You shouldn't notice it at idle though.

I wouldn't put any plug n plays until I was satisfied that there wasn't another issue present, but that's just me.

Garry
 

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Your welcome. That's why I'm here.
Sneaking in to steal the glory.......typical move from a guy who doesn't care about watching professional sports on TV! :biggrinjester:
 

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:bigthumb::alfdance::biggrinjester:
I don't give a darn about pro sports either, with the exceptions of car stuff, world's strongest man competition, and some boxing - and anything that involves scantily clad hot chicks. Okay, I'll stop being off topic now.
 

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Displacement on demand
The 2005 Chrysler 300C and Dodge Magnum RT were the first high-volume, modern production vehicles in North America to feature fully-functioning cylinder deactivation; at Chrysler, they were followed by the 2006 Durango (Honda came out with a cylinder-deactivating V6 later). The MDS (“multiple displacement system”) seamlessly alternates between fuel economy in four-cylinder mode, and power in V-8 mode. Owners receive the powerful benefit of the Hemi engine with the fuel economy that they would expect from a less powerful V6 engine. Most test drivers cannot tell the difference.
"The MDS was part of the engine's original design," said Bob Lee, Vice President Powertrain Product Team, Chrysler Group. "This resulted in a cylinder-deactivation system that is elegantly simple and completely integrated into the engine design. The benefits are fewer parts, maximum reliability and lower cost."
This system should triumph where the Cadillac 4-6-8 failed because of the speed of modern electronic controls, the sophistication of the algorithms controlling the systems, and the use of electronic throttle control. The HEMI will be able to transition from eight cylinders to four in 40 milliseconds (0.04 seconds).


The system deactivates the valve lifters. This keeps the valves in four cylinders closed, and there is no combustion. In addition to stopping combustion, energy is not lost by pumping air through these cylinders.
Fuel economy gains go up to 20 percent under various driving conditions, with a 10 percent (or so) aggregate improvement, without any change in customer experience—drivers will receive the benefit without changing their driving habits or losing power.
An LX engineer said that the Hemi was in part inspired by the slant six - in particular, the dual oiling circuit, with oil coming through the pushrods. This could maintain lubrication when cylinders are at rest.
Don Sherman's article in Automobile noted described a test of the MDS. They found that only four cylinders were used during 17% of the suburban traffic portion of the test, during a full 48% of the freeway test which included "over 70 mph" speeds. Overall, they found that the engine powered down to four cylinders about 40% of the time. Non-enthusiast drivers may experience even more savings. As with most testers (including us), Don was generally unable to detect the changes from four to eight cylinders and back again.
Bob Sheaves discussed why the system is almost always used on V8s and not V6s:
"An Otto cycle engine requires 2 full revolutions of the crankshaft to fire all the cylinders. Therefore: 2 x 360=720 degrees of rotation. Dividing that total rotation by the number of cylinders to have an even firing engine (naturally balanced) will give you 120 degrees, which means that you have a cylinder firing every 120 degrees of rotation. When you take out 3 of the cylinders, you have increased the firing rotation to 240 degreees (720/3), still balanced between each firing of a cylinder. The catch is that you have now increased the harmonic vibrations as the rpms increase. Deactivation of four cylinders in a V6 would mean losing the multiple of six cylinders that will keep the engine in primary balance. (The lack of natural balance is why balance shafts are often used in 90 degree V6s and larger inline 4 cylinder engines.)"
Chrysler engineer Cole wrote: "The modern HEMI always shuts off the same four cylinders. In our duarability test cycle (150,000 customer equivelant miles driven at the 95 percentile, meaning that only 5 percent of our owners are more abusive than our testing), we have not found any adverse wear patterns." (Chrysler PR materials boasted of “over 6.5 million customer-equivalent miles through development and durability testing.”)
 

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Discussion Starter · #15 ·
Another way to tell if it is coralated with mds is to check evic. Scroll through your options to mpg, it will show when you are in fuel saver (mds) mode. It will definately sound different with aftermarket exhaust...search for exhaust drone. Using Auto stick in 1-5 will negate mds kicking in. You shouldn't notice it at idle though.

I wouldn't put any plug n plays until I was satisfied that there wasn't another issue present, but that's just me.

Garry
how do you check evic with no buttons on steering wheel? hold trip reset down with ignition off and then turn on?
 

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how do you check evic with no buttons on steering wheel? hold trip reset down with ignition off and then turn on?
Not all R/Ts have evic. If you have a base R/T (as I do), you don't have evic. At least I don't, and if you don't have buttons on your steering wheel, you probably don't have evic.
 

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hmm, didn't think about not having evic. Try autosticking that should lock out mds to determine if you still have the sound.

Garry
 

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Another way to tell if it is coralated with mds is to check evic. Scroll through your options to mpg, it will show when you are in fuel saver (mds) mode. It will definately sound different with aftermarket exhaust...search for exhaust drone. Using Auto stick in 1-5 will negate mds kicking in. You shouldn't notice it at idle though.

I wouldn't put any plug n plays until I was satisfied that there wasn't another issue present, but that's just me.

Garry
Not all R/Ts have evic. If you have a base R/T (as I do), you don't have evic. At least I don't, and if you don't have buttons on your steering wheel, you probably don't have evic.
FYI, the 2006's don't have the Fuel saver info built into the EVIC display. 2007 was the first year for that.
 

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Discussion Starter · #19 ·
well i dont think its the mds , cause it does it with the auto stick and it does it sometimes in lower gears , i got the predator but havent installed it yet until i can figure out what it is first.im picking up the tie rod end this weekend and fixing the esp bas light to see if by chance it could be that. you have to be smarter than the car you work on .... these cars today are too damn smart lol
 

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well i dont think its the mds , cause it does it with the auto stick and it does it sometimes in lower gears , i got the predator but havent installed it yet until i can figure out what it is first.im picking up the tie rod end this weekend and fixing the esp bas light to see if by chance it could be that. you have to be smarter than the car you work on .... these cars today are too damn smart lol
tie rods will not cause the esp/bas light to come on. Mine came on but I can offer no help, because I brought it in for warranty and they just fixed it.

I don't mean to insult your mechanic intelligence... and I'm not mechanically savy..

I rule out timing though due to the fact that it messes up during acceleration and at faster speeds...

Plugs could still possibly be an issue? Or wires?

Fuel pump could be messing up?

Do our cars have fuel pressure regulators?

Could a valve be bent or damaged?

How many miles?

This info was more or less for you to ponder, I only guess.. with old fords I'm typically right.. anything else I am not too educated.
 
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