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Alex
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PostPosted: Fri Oct 25, 2002 9:34 pm    Post subject: Re:O/D Question Reply with quote

glideslope wrote:
I don't think I'm mistaking the lock up for a 5-4 downshift, am I? I count 5 gears as I go up the on ramp.


Well, it well might be. When you do 65 mph in 5th gear your engine would run at approximately 2000 rpm. Drive ratios of the 5 speed tranny in 4th gear = 0.935 and in 5th = 0.685, so the ratio difference is 1.36 times. Which means that 4th gear @ 65 should give you somewhere about 2700 rpm which is close to what you have observed. Also I noticed that on my '00 MPV, the torque converter clutch engaging/disengaging causes the engine speed change of (estimating here by memory) about 300-400 rpm. I don't think that on 02 model that would be much different...

I'm just speculating here based on my best judgement and documentation I have. I drove 02 only once during a brief test drive, so I don't have much experience with it (yet) and maybe other 02/03 MPV owners can help clarify this for us.
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Alex
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PostPosted: Fri Oct 25, 2002 10:33 pm    Post subject: Re:O/D Question Reply with quote

Ok, I dug something more from the workshop manual. See the attached table. Note that in "D" with O/D OFF engaged or even in "3" and "2" the tranny can shift into up to 5th gear to protect engine from overspeeding (read the note below the table).

So, I guess, during normal driving conditions when O/D OFF is depressed, the tranny tries to stay in 4th gear.

Also, there is another table that shows what tranny subsystems are affected by each switch and it shows that O/D OFF switch doesn't affect torque converter clutch (TCC). TCC is affected by the following input signals: gear selector position, engine speed, vehicle speedometer sensor, tranny fluid temperature sensor, brake switch, and throttle position.

I hope the info is interesting and helpful.




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subearu
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PostPosted: Fri Oct 25, 2002 10:47 pm    Post subject: Re:O/D Question Reply with quote

Maybe it's just getting past my bedtime, but I'm reading it as it won't downshift into the lower gear until it's below the max rpm for the gear downshifting into.

I'm going to get some realworld data tomorrow with our ES. I'll post results then.

Very cool info, btw.

-Brian

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Alex
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PostPosted: Fri Oct 25, 2002 10:57 pm    Post subject: Re:O/D Question Reply with quote

subearu wrote:
I'm reading it as it won't downshift into the lower gear until it's below the max rpm for the gear downshifting into.


My understanding is that it should read upshift instead of downshift. But still, I'm not sure if going 65 mph in 4th gear would require going into 5th "to prevent engine overspeeding"... So, Brian, let us know what you can find out tomorrow...
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glideslope
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PostPosted: Sat Oct 26, 2002 7:21 am    Post subject: Re:O/D Question Reply with quote

Alex,

Thanks for that very informative post. I appreciate your efforts. I'm looking forward to some real world posts. It looks like the direct clutch engauges no matter what the switch position is. I guess I just don't understand why both the 02's I drove shift through 5th with the switch On. I drove my 02 this morning to get some Java and the RPM difference is actually around 500-600 not 800.

Thanks a million,
Mark.

p.s. I'm going to review my numbers with my 5 year old after soccer today just to insure I'm not at fault.

wave

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03 Steel Grey Metallic 6s. Auto, Side Air Bags/ Side Curtain Air Bags, Rear Stone Guards, Wheel Locks.
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subearu
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PostPosted: Sat Oct 26, 2002 1:00 pm    Post subject: Re:O/D Question Reply with quote

Ok, here's my findings:

gear selected = 2. O/D on. Only uses 2nd gear
gear selected = 2. O/D off. Only uses 2nd gear

gear selected = 3. O/D on. Uses 2nd and 3rd gear
gear selected = 3. O/D off. Uses 2nd and 3rd gear

gear selected = D. O/D on. Uses 1st, 2nd, 3rd, 4th, 5th, locks up 4th at ~35mph, locks up 5th at ~45mph
gear selected = D. O/D off. Uses 1st, 2nd, 3rd, 4th, locks up 4th at ~35mph

in '3', 40mph is at about 2600 rpm
in 'D', O/D on, 40mph is at about 1700 rpm, 50mph is at about 1500 rpm

Note: the '~' symbol is being used to represent 'about' or 'roughly'

-Brian

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subearu
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PostPosted: Sat Oct 26, 2002 4:57 pm    Post subject: Re:O/D Question Reply with quote

whoops, forgot one:

in 'D', O/D off, 40mph is at about 1700 rpm, 50mph is at about 2200 rpm

-Brian

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glideslope
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PostPosted: Sun Oct 27, 2002 7:52 am    Post subject: Re:O/D Question Reply with quote

Brian,

Thanks for the real world test. My 02 performs the same. Now that I understand the tech data that Alex posted I can better decipher the shifting.

You both have been very helpful.

Mark. Smile

Emerald Mica 02 MPV LX. 4-Seasons, Luxury Pkg, Fog Lights, Rear Step, Roof Rack, Mud Guards, Cargo Net.
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cpapashley
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PostPosted: Tue Sep 19, 2006 5:39 pm    Post subject: Re:O/D Question Reply with quote

Alex wrote:
I know that on mine (2000) with the 4 speed automatic we have the current gearing options:

Shifter is in:

"1" - tranny stays in 1st gear always
"2" - tranny stays in 2nd gear always
"D" - tranny shifts through 1-2-3-4-3-2-1
"D" with OD OFF - tranny shifts through 1-2-3-2-1

So the O/D OFF switch just blocks the transmission from going into 4th gear. It is still "automatic" in a sense that the tranny doesn't stay in 3rd and can downshift into 2nd or 1st if needed.

The torque converter locks up automatically when the certain speed is reached and throttle is at certain position. According to the transmission shifting diagram, the TC can be locked only when in 4th gear. If you press the gas harder when in 4th gear, then first TCC (torque converter clutch) disengages, and if that's not enough to get more torque, transmission downshifts to 3rd.

From the diagram, if you accelerate really slowly (throttle opening less than 2/Cool then the tranny should go in 4th gear at about 40 km/h. Then TCC engages at approximately 70 km/h. If you start to decelerate slightly, TCC disengages at approx. 55 km/h. Which means that you cannot have torque converter locked below that speed. So, if you have fuel efficiency, drive above 60 km/h...

Oh, BTW, I didn't know that but according to the service manual, the 4 speed tranny in 00/01 has three modes - NORMAL, SLOPE, and POWER. Here is a quote: "The PCM automatically switches between NORMAL and SLOPE modes corresponding to the engine load and vehicle acceleration ... [it] automatically switches between POWER and NORMAL modes according to speed at which the accelerator pedal is depressed"...


I am starting to wonder what is possessing my MPV, I decided to do a bit of testing with the O/D button off on our '00 mpv. Seems that it starts in 2nd and changes early to 3rd. No good if there is start stop. Yet reading this post (yes I know I have resurrected another old thread) it states that it should go 1st>2nd>3rd>2nd>1st.

So I am confused, I wonder if the PCM has had a fit?? Confused

Edit*****

Well thought I would check the manual and hey presto it all became clear...the button is a hold button and not an O/D button as in our previous car.

So it works like this


Quote:
For Australian Model '00 MPV

Shift patterns without hold mode:

D=1st, 2nd, 3rd, 4th
S=1st, 2nd, 3rd
L=1st, 2nd

Shift patterns with hold mode on:

D (Hold) = 3rd, (temporarily 2nd for standing start)
S (Hold) = 2nd (fixed)
L (Hold) = 1st (fixed)


So mystery solved for me, will be trying out the S for local school drop to see if it reduces the fuel consumption any.
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