4 Cylinder shutdown tune - MDS Powerstroke?
#1
#2
Looking at the tuning tables, I don't see how it would even be possible. The PCM stores the tables for fueling in relation to TPS, ICP, Mass Fuel, etc. Not a single table accounts for individual injectors, or a bank of injectors.
Out of those tables, fueling demands are sent to the IDM. From there, the IDM determines how long to open each injector. Basically, the PCM sees a single injector as all of them at once. The IDM takes that information and splits it to individual injectors... in a rough manner to put it.
Now for my crazy theory side of all of this: Since we can't tune an IDM, the only way to mimic any kind of MDS function would have to be a manual switch tied into a bank of injectors, and that switch would cut power manually when flipped. Of course, there would not be any way to control the balance of when injectors fire or don't fire. In addition, cutting power to the injectors is just like having a UVC harness come loose. It would trigger SES codes.
From what I've read in the past (and believe me, I'm no MDS expert ), MDS doesn't just cut out an entire bank of injectors. It selectively fires injectors in different sequences in order to maintain a balance and keep the engine running smooth. At least that's the cliff notes version of how I understand it. Say that you have a V8, and the firing order (for simplicity sake) is 1-2-3-4-5-6-7-8. MDS doesn't automatically cut out 2-4-6-8 or vice versa. It might fire 2-3-7-8 one time around, then 1-2-5-6 the next time around.
The firing order of our engines doesn't work well for just cutting out either one side or the other, as the engine can really keep running at that point, and you wouldn't be able to maintain any speed at all.
Anyway, that's my 2 cents.
Out of those tables, fueling demands are sent to the IDM. From there, the IDM determines how long to open each injector. Basically, the PCM sees a single injector as all of them at once. The IDM takes that information and splits it to individual injectors... in a rough manner to put it.
Now for my crazy theory side of all of this: Since we can't tune an IDM, the only way to mimic any kind of MDS function would have to be a manual switch tied into a bank of injectors, and that switch would cut power manually when flipped. Of course, there would not be any way to control the balance of when injectors fire or don't fire. In addition, cutting power to the injectors is just like having a UVC harness come loose. It would trigger SES codes.
From what I've read in the past (and believe me, I'm no MDS expert ), MDS doesn't just cut out an entire bank of injectors. It selectively fires injectors in different sequences in order to maintain a balance and keep the engine running smooth. At least that's the cliff notes version of how I understand it. Say that you have a V8, and the firing order (for simplicity sake) is 1-2-3-4-5-6-7-8. MDS doesn't automatically cut out 2-4-6-8 or vice versa. It might fire 2-3-7-8 one time around, then 1-2-5-6 the next time around.
The firing order of our engines doesn't work well for just cutting out either one side or the other, as the engine can really keep running at that point, and you wouldn't be able to maintain any speed at all.
Anyway, that's my 2 cents.
#3
I have experimented with my break out box in my cab. I could not find a happy 4 or a balance. It vibrated terribly. I flipped different injectors off to fine a happy spot. Nothing. I didn't fool with it long because i didn't want to mess something up. I couldn't find a smooth running 6 or 4 cylinder diesel.
I thought of possibly knocking down to 4 cylinders while on at cruising speeds empty to see if i could experiment with Fuel mileage while i was board one day. Futile attempt i know but i was bored.
I thought of possibly knocking down to 4 cylinders while on at cruising speeds empty to see if i could experiment with Fuel mileage while i was board one day. Futile attempt i know but i was bored.
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mds47588
1980 - 1986 Bullnose F100, F150 & Larger F-Series Trucks
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01-26-2009 08:43 PM