drwhosc

Ok after several months, and a transmission rebuild later, I got the tranny back in my 88 S4, and things are mostly good. The transmission needed a rebuild because I lost 4th gear. When I got in there, I replaced the bands, the clutch pacs and found a seal had loss about ¼ of itself. So all that was fixed. I did not do anything to the valve body. Put is all back in, filled the fluids, go the right levels, checked the modulator and governor pressures, all in spec.

I adjusted the cables as noted in many post in the following order,
1. cable to TB with little slack (2-3mm play)
2. cable to pedal with little slack (2-3 mm play)
3. Bowden cable with no slack (< 1mm)
4, cruise control with lots of slack.

1 do need help with some of the tweaking after the road test. The car now does shift though all the gears, and I have 4th gear (woo hoo), but in general I am getting late shifts. The RPMS will go up to 4K before some of the shifts occur. This is especially true if I have the drive train under load. Ie I am pushing the car. If I back off, I do get a shift almost immediately.

Checked the kick down, and it is working, but down not seem to be interfering with the shifts.

One other thing that might be related, my idle is behaving a bit funny and I have not worked it up yet. At low idle with the car in gear, the rpms will hit about 500- 750, so a bit low. With the car in park the idle will run at about 1200, so a bit high. Also when i fist pull off, I have a hesitation. I have not tested to see if this is the case in park or not, but prior to the rebuild, the engine ran flawlessly.

So I need to know why do I get different behaviors when the car is under load. Seems like the shift points are OK, but delayed under load. Can all of this be related to a vacuum issue?

The Car is quite drivable, but I know it can do better.

76FJ55

first thing I'd try is disconnecting the kickdown cable and taking it for a short drive. this will make it so the transmission shifts without influence of throttle position, and therefore should shift at a lower RPM. My brother was looking at a 500 series MB. initially thought the trans had problems in addition to the engine's poor state of tune. after disconnecting the kickdown the trans shifted great. the problem was that the car needed excess throttle to accelerate and hold speed, so even though it didn't feel like you where driving the car hard (because of the lack of power) the throttle input caused high RPM shifts.

Mrmerlin

Check the vacuum modulator for a leak free system at the vacuum splitter under the MAF, if its leak free reconnect the hose to the 6 way splitter.

For the varying idle
inspect the 2 plastic connectors that plug into the sides of the MAF boot for cracks or holes, the plastics are easy to damage if they are old.

Also consider replacing the MAF with a fresh unit as the high idle in neutral could be caused by a bad MAF

OK to set up the throttle quadrant,

first remove the bowden cable cup then

set the throttle cable to quadrant,
(this is the one that goes around the wheel)

you want to be able to have the arm that has the ***** on it move about 1 to 2 MM till you hear a click from the TPS, adjust this cable as necessary.

once this is done then set the gas pedal cable onto the ball, this should have slack of 2mm.
have a helper put the pedal to the floor while you check for WOT, adjust as necessary

BUT make sure the throttle arm returns to its stop and the TPS is clicking.

Next set the bowden cable to the ball ,
test it by gently pulling the cable see if you feel resistance this indicates its connected to the kickdown arm in the trans. let it slide back to the no tension position
it should fit with no slack or tension ,
in other words it should slip fit on with no slack in the cable..
Get some wrenches that fit the ball and locknut and cable, drive the car see if it will run to redline and then shift, if its shifting early then the cable is loose, adjust the cable by a 1/2 turn, keep testing till you get consistent shifting,
once your close to perfect then reduce the adjustments to just 1/4 turn of the ball cup on the bowden

drwhosc

thanks for the help.

redid the quadrant, and started witht he bowden cable lose. Shifting better, now early, but slowly working the tension back on the cable. Also have a late shift flare, so more reading in the wsm.

Speedtoys

What do I adjust to stop the downshifts when adding throttle..from happening as soon? I feel that the throttle-downshift is just a bit quick to happen right now.

Bill Ball

The idle should be 650-700. So, 500-750 is close, not low, and 1200 is WAY high, not just a bit high, once the engine is warmed up. The idle should change very little between park and being in gear. You have substantial vacuum leak somewhere. Also, there is no reason to have any slack in either section of the throttle cable UNLESS the idle switch will not trip.

drwhosc

thanks bill, I was afraid that I have a vacuum leak giving the behavior. this one is going ot be tough to track down. I can't hear anything. I will begin my research. Also I don't really hear a clcik when the throttle is fully closed. got to work that up as well.

thanks, It is cold, so it might take me a bit to get back to the car.

Bill Ball

The throttle idle switch click is faint but should be audible in a relatively quiet area. If you don't hear it, loosen the cable a fair amount. The click should occur just a couple of degrees off the idle stop. If you still don't hear it, then either the throttle switch housing is out of adjustment or it is broken. In either case the intake must come off. If the intake area has not been "refreshed", then this would be the time. If the idle switch is not working, the idle will be goofy, like you are seeing. Once it is working properly, you can pull all the slack out of the throttle cable, as long as you stil hear it click when the throttle is released and when it is pulled of the idle stop.