Chrysler 300C & SRT8 Forums banner

1 - 19 of 19 Posts

·
Registered
Joined
·
159 Posts
Discussion Starter #1
Just thinking.... If the MDS system is pressure activated system, can we have a gauge or light on the dashboard signling when it's active. Kinda like the up-shift gauge that was installed for standard transmissions a few years back. My friend had a Jeep Wrangler that had one. Useless for shifting, if you asked me, but in this case.... Hmmmm

For those of us that are just inquisitive, like I will be. :)
 

·
Registered
Joined
·
12 Posts
I wondered the same thing... Since it is a true dual exhaust only one of the headers would have flow when only half the bank is running. I wonder if that would be a way to let the drive know when it's on or off.

1998 Dodge intrepid
 

·
Premium Member
Joined
·
702 Posts
Im pretty sure that cylinders on each half of the motor are running even when MDS is active. They de-activate a couple cylinders on each side...

A gauge should be able to be rigged up, surely some circuits receive voltage when this is active, and if so, it would be possible to wire in a gauge to reflect that.
 

·
Registered
Joined
·
12 Posts
I stand corrected, even before your reply I did see that two cylinders/bank are what deactivate. Someone will get creative with an aftermarket switch.
 

·
Registered
Joined
·
1 Posts
MDS is activated by a solenoid thats near the lifters. When my 300C arrives, I will take a look to see if there are any plugs or wires near those solenoids that activate or deactivate the lifters. If the plugs are obvious then it would be easy to wire in an indicator that shows which cylinders are in use. My guess though is that the wires that activate the solenoid are probably very hard to find. It might require taking off the heads to get to them. Ill let ya'll know what I find when my 300C arrives.
 

·
Registered
Joined
·
159 Posts
Discussion Starter #6
Cool thanks, It would just be really nice to know when the beast is sleeping.:)
 

·
Registered
Joined
·
12 Posts
If you had a choice, would you like something that blinks all the time (showing which cylinders are active) or simply has a "I'm currently in 4 cyl mode" indicator?
 

·
Registered
Joined
·
5 Posts
I read in one of my Chrysler magazines that they were originally going to put a light in the dash telling you when it the car was in four cylinder mode, but it goes in and out so often the proposed light was simply an annoying flashing light. Funny!

Dave
 

·
Registered
Joined
·
159 Posts
Discussion Starter #12
I missed reading something about the 300? Hmmm... how could that be?:)

I think this is good news in disguise... Now we know there must be a way to do it.

(**OK, and maybe a in-line switch to be able to turn it on and off. ;))
 

·
Registered
Joined
·
14 Posts
I would think that some indicator for 8 CYL mode would be better that one for 4CYL mode. My impression is that the car is in 4CYL mode more than in 8. The car would be in 4CYL mode when at lights and when at cruising speed on the highway and even times when you arent accelerating too hard.
 

·
Registered
Joined
·
167 Posts
I like the "on/off" switch idea the best. Especially with prices at the pumps. I can just imagine keeping it at 4cyl and switching it to 8 cyl if someonse starts reving at lights trying to be funny.
 

·
Registered
Joined
·
4 Posts
superdave said:
I read in one of my Chrysler magazines that they were originally going to put a light in the dash telling you when it the car was in four cylinder mode, but it goes in and out so often the proposed light was simply an annoying flashing light.
Yes, this is true. There's no delay in the logic, so the system cycles on/off continuously.


The following is from here:

works between 1000 and 3000 rpm, or about 15 to 80 mph.

Threshold is if the vehicle can maintain it's course utilizing less than 95% of torque available from only 4 cylinders, it will then cut 1, 4, 6, and 7. Changeover occurs in approx 50 to 80 milliseconds. There is no delay reaction built into the logic, it will cut the cylinders as soon as that threshold is attained.

The valve lifters are dissabled, and one burned charge is retained withing the cylinder(s). The charge acts as an "air spring", allowing the engine to "lose less" energy than just cutting a fuel injector and flowing air through the combustion chamber. This one charge is cycled out/new one in after a certain period of time due to gas blow-by the piston rings reducing efficiency. Once temperatures stabilize (few seconds or so, environment dependent) the cycle repeats itself.

The system works continuously for a maximum of six minutes, after which the four cylinders come back on-line, to stabilize cylinder temperatures, and maintain combustion, emissions, and mechanical efficiency.
 

·
Registered
Joined
·
254 Posts
I was discussing this with one of the Chrysler Designers/Engineers. Chrysler purposely left that feature out. They were worried that the bad rap of the 4-6-8 would scare off consumers.
 

·
Registered
Joined
·
113 Posts
Now that I've unmuzzled the exhaust, I can hear precisely when the MDS shifts from 4 to 8 then to 4 then to 8, back to 4, now 8, 4 again, there goes 8, 4, 8, 4, 8....

If they had put an indicator on the dash for the MDS the sucker would blink on and off more frequently than Rosie O'Donnel's refrigerator light. Without a doubt the MDS is linked to the torque, as it seems to desire four cyclinder mode whenever possible...but even the slightest touch of the accelerator and the entire choir chimes in. This morning it was putting along in 4 cylinder mode when suddenly a field mouse darted in front of my car. With just a slight foot tap the V8 lunged forward transforming the pest into a waffle pressed stain treatment, and then the engine quietly slipped back to 4 cylinder mode. All I could think was "Gosh, I'm virtually an environmentalist in this green machine!".
 
1 - 19 of 19 Posts
Top