Auto Transmission Adjustments
#1
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Auto Transmission Adjustments
This is a quick list of the basic adjustments for the automatic transmission...
First, check the adjustment of the cable from the throttle pedal to the quadrant. You are aiming for somewhere between almost zero slack but zero pre-load.
Next, check the adjustment on the cable from the quadrant to the throttle body. Again, just a tiny bit of slack. Check for the throttle switch click that should happen as soon as you move the throttle pedal. Check for wide-open throttle. Check the closing of the WOT switch at about two-thirds throttle. No click - you have to check at the ECU connector. You can check the idle switch at the same time.
The cruise control cable should always have some slack.
Under the car on the driver's side of the transmission, find the vacuum modulator. Check for full manifold vacuum - measure the vacuum at the manifold (make sure that you are measuring raw manifold vacuum - no check valves or boosters), then measure the vacuum at the hose at the modulator. The readings should be the same. If not, fix the leak.
With the car in a quiet place, turn the ignition switch on and roll down the widows. Push the throttle to the floor and listen for the click from under the car at full throttle. This is the kick-down solenoid. The kick-down solenoid activation makes the transmission more reluctant to upshift, more anxious to downshift.
When these are correct, start adjusting the transmission cable. Tighten a little, drive for a couple of days. Repeat until you like the speeds at which the transmission shifts.
If necessary, adjust the modulator to soften or firm up the shifts. The cable adjusts shift speed, the modulator adjusts shift firmness.
First, check the adjustment of the cable from the throttle pedal to the quadrant. You are aiming for somewhere between almost zero slack but zero pre-load.
Next, check the adjustment on the cable from the quadrant to the throttle body. Again, just a tiny bit of slack. Check for the throttle switch click that should happen as soon as you move the throttle pedal. Check for wide-open throttle. Check the closing of the WOT switch at about two-thirds throttle. No click - you have to check at the ECU connector. You can check the idle switch at the same time.
The cruise control cable should always have some slack.
Under the car on the driver's side of the transmission, find the vacuum modulator. Check for full manifold vacuum - measure the vacuum at the manifold (make sure that you are measuring raw manifold vacuum - no check valves or boosters), then measure the vacuum at the hose at the modulator. The readings should be the same. If not, fix the leak.
With the car in a quiet place, turn the ignition switch on and roll down the widows. Push the throttle to the floor and listen for the click from under the car at full throttle. This is the kick-down solenoid. The kick-down solenoid activation makes the transmission more reluctant to upshift, more anxious to downshift.
When these are correct, start adjusting the transmission cable. Tighten a little, drive for a couple of days. Repeat until you like the speeds at which the transmission shifts.
If necessary, adjust the modulator to soften or firm up the shifts. The cable adjusts shift speed, the modulator adjusts shift firmness.
#2
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#3
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Check for wide-open throttle. Check the closing of the WOT switch at about two-thirds throttle. No click - you have to check at the ECU connector. You can check the idle switch at the same time.
If necessary, adjust the modulator to soften or firm up the shifts. The cable adjusts shift speed, the modulator adjusts shift firmness.
On my 928 the wide open throttle switch does not work. I discovered this when sharktuning. From a fuelling perpsective the wide open throttle map is disengaged and I rely on custom fuelling of the main map to achieve the AFFR I was looking for.
One thing I never thought about was whether the wide open throttle switch failure has any impact of the transmission performance. Whereas I have a spare throttle switch, changing it is a pain in that the inlet manifold has to come off and I could not be bothered.
As I can tell the auto box works really well. I set my kickdown cable about 3 turns tight and I also by-pass the kick down switch, but can disengage the link to give normal type shifting. However, I like it jumped.
If I understand your note correctly, not having the throttle wide open switch working might have some consequences that I do not seem to have twigged. Any thoughts as to what if any symptoms I might experience as a consequence?
All I can say is that when I hammer it, the car feels rear end twitchy as it changes up on full throttle. Is this a natural torque reaction or as I think about it, is it a consequence of ignition retard not being applied when changing gears?
I do not seem to have any other obvious adverse effects and the motor seems to rev nicely before changing up at something over 6k rpm.
Ironically I still have issues with the tach signal breaking down at high revs just as it did on my late S4. I suspect this is something to do with our high temps causing some resistor to break down thus corrupting the tach signal which generally seems to go haywire at about 5k [most of but not all of the time].
Regards
Fred R
#7
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Fred,
I am not aware of any effect that the WOT switch has on the transmission - AFAIK, it affects engine tuning only.
If I were flushing, I would use the method that disconnects the transmission cooling line returning to the transmission. Disconnect the line, idle the engine until the fluid stops coming out. Drop the pan, change filter and gasket, clean pan and install. Add about as much fluid as you got out, idle the engine until the fluid stops. Add fluid, repeat until the fluid coming out appears newer/cleaner. Connect line, fill to between top lines with car level front-to-rear and side-to-side. I would use Dexron VI, as it appears to be the best fluid currently available.
I am not aware of any effect that the WOT switch has on the transmission - AFAIK, it affects engine tuning only.
If I were flushing, I would use the method that disconnects the transmission cooling line returning to the transmission. Disconnect the line, idle the engine until the fluid stops coming out. Drop the pan, change filter and gasket, clean pan and install. Add about as much fluid as you got out, idle the engine until the fluid stops. Add fluid, repeat until the fluid coming out appears newer/cleaner. Connect line, fill to between top lines with car level front-to-rear and side-to-side. I would use Dexron VI, as it appears to be the best fluid currently available.
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#9
Wally,
You are a true credit to the 928 community.
I am active on several message boards for another type of car, and none of the regular contributors has the depth of knowledge you have on the shark. For many years of helpful advice, I thank you very much.
You are a true credit to the 928 community.
I am active on several message boards for another type of car, and none of the regular contributors has the depth of knowledge you have on the shark. For many years of helpful advice, I thank you very much.
#10
Wally: I have my bowden adjusted so the ball socket just slips on with a tiny bit of tension. My upshifts are still a bit early. I was going to tighten it more but I didn't want to pull it out too far at WOT. Is there any danger in doing this? Would another method be have a helper hold the pedal at WOT and pull the bowden cable out as far as it goes by hand and adjust it to slip on? This would give it maximum stroke at WOT.
#11
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You can certainly use that method to check the max adjustment if you want - but I doubt that you will really want it adjusted that far.
#12
Drifting
Sorry to jump in, but I need help with the dash indicator lights for the automatic '90 S4. The R, N & D lights work. But the P, 2 & 1 does not work. Where is the actual connection that cycles thru the gears to light the particular dash indicator?
Thanks
Thanks
#13
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The actual switch is on the side of the transmission at the shift cable.
The wires for the lights go thru Connector T50, a six-terminal connector located in the corner of the spare tire well. This is a common problem area - clean the connection carefully.
The wires for the lights also go thru Connector T19, a 26-terminal connector located near the Central Electric Panel on the right side of the under-dash area. Clean this connector as well.
If cleaning the connectors doesn't help, you may need to change the bulbs - but the 1 and 2 bulbs don't see much use. The connections for the bulbs, or the connector for the cluster, could also be dirty.
The wires for the lights go thru Connector T50, a six-terminal connector located in the corner of the spare tire well. This is a common problem area - clean the connection carefully.
The wires for the lights also go thru Connector T19, a 26-terminal connector located near the Central Electric Panel on the right side of the under-dash area. Clean this connector as well.
If cleaning the connectors doesn't help, you may need to change the bulbs - but the 1 and 2 bulbs don't see much use. The connections for the bulbs, or the connector for the cluster, could also be dirty.
#14
Three Wheelin'
Join Date: Nov 2004
Location: Gatineau/Ottawa Canada 84 928S triple black
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I also have a question for Wally :
84S From 1st to 2nd at WOT it shifts at only 4KRPM but from 2nd to 3rd it goes to red line +/-.. what gives?
Note : I will go trough the steps you mention in first post in the near future.
Thanks
84S From 1st to 2nd at WOT it shifts at only 4KRPM but from 2nd to 3rd it goes to red line +/-.. what gives?
Note : I will go trough the steps you mention in first post in the near future.
Thanks
928, 928s, 944, adjust, adjustment, adjustments, auto, automatic, bowden, cable, change, shift, throttle, transmision, transmission