Comparing Mercon V, ATF+3, ATF+4 specs

[G-MAN]

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Originally posted by the_oil_dealer:

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Originally posted by G-Man II:

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Originally posted by the_oil_dealer:
Of course there was no duty control, but rather line pressure was controlled by the "kickdown" cable.

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Then it wasn't totally electronic.

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okay.. maybe not but it didnt make unessecary buzzing noises whenever you pulled up to a light!!

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Those "buzzing noises" that a Chrysler tranny makes are the solenoids the TCM uses to downshift the transmission. The noise is there for every upshift and downshift, it's just that the overall noise level is low enough when the car is coming to a stop that you can hear it if the windows are down, or if you're standing by the car.

One cool thing about electronic solenoid control of the shifting is that the cruise control can actually downshift the tranny to maintain speed when going down a hill.

 

[Ray H]

My 2003 Hyundai Sonata seems to downshift (or at least disengage torque converter lockup) on steep downgrades, too. Given DaimlerChrysler's "cooperation" with Mitsubishi and Hyundai, perhaps sharing this design philosophy shouldn't be surprising. In any event, I'd rather, if the PCM module is indeed involved, that it activate the vehicle braking system to achieve speed retarding. Brake pads are cheaper and much easier to service than worn transmission friction facings. Having the braking lights illuminate during these cycles would additionally be visual warning for following drivers, too.

 

[G-MAN]

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Originally posted by Ray H:
My 2003 Hyundai Sonata seems to downshift (or at least disengage torque converter lockup) on steep downgrades, too.

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There is no "seem" to it with my Chrysler. On steep downgrades my transmission shifts down to 3rd gear to maintain the speed I have set.

BTW, on a downgrade, disengaging the coverter lockup would increase your forward speed, wouldn't it?

 

[Ray H]

I don't believe so. Fluid turbulance through the unlocked convertor blades would further retard momentum over what would be achieved by compression braking alone in high gear when the fuel injectors shut down. It's by no means equivalent to shifting into "Neutral".

 

[the_oil_dealer]

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Originally posted by brianl703:

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Originally posted by the_oil_dealer:
Ford coded any electronic 4speed auto as 4EAT.

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They had the CD4E,introduced in 94/95, I got the impression that everyhing they call 4EAT is a Mazda-derived design.

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youre right, sorry I'm used to posting on the Ford Probe/MX-6 boards

 

[the_oil_dealer]

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Originally posted by G-Man II:

Originally posted by Ray H:
[qb]BTW, on a downgrade, disengaging the coverter lockup would increase your forward speed, wouldn't it?

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this has been my experience as well. Torque converters slip both ways

 

[brianl703]

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Originally posted by the_oil_dealer:
Ford coded any electronic 4speed auto as 4EAT.

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They had the CD4E,introduced in 94/95, I got the impression that everyhing they call 4EAT is a Mazda-derived design.

Then there's the AODE, a 4 speed electronic version of the AOD.

And the AX4N/AX4S/AXODE, also 4-speed electronic transmissons.

 

[brianl703]

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Originally posted by G-Man II:
I've owned half a dozen cars with cruise control, both domestic and foreign and my 99 Chrysler is the only one I've ever had that will downshift on a steep hill to maintain speed.

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That is probably because on most cars, the cruise control is not integrated into the powertrain control module and it has no way of signaling the powertrain control module to downshift.

I would bet that on the 99 Chrysler the cruise control module is either part of the powertrain control module or is connected to the vehicle's databus and can signal the PCM to invoke a downshift.

For a couple of model years in the late-early 90s, Ford was putting cruise control functions in the PCM but they stopped doing that and went back to a standalone cruise control setup. I read somewhere--and I'm not sure if there's any truth to it--that there was some sort of product liability concern with the integrated cruise control and that's why they stopped doing it.