Hey guys, I recently had a lot of acceleration/shifting troubles and thanks to Jerry Bransford I traced it back to a Throttle Valve (TV) cable issue. As far as I understand it, the TV cable is the relationship between the throttle body and the transmission, acceleration and shifting.
Here is an excerpt from the factory service manual (FSM) about the TV cable:
Quote:
The transmission throttle valve is operated by a
cam on the throttle lever. The throttle lever is operated
by an adjustable cable (Fig. 177). The cable is
attached to an arm mounted on the throttle lever
shaft. A retaining clip at the engine-end of the cable
is removed to provide for cable adjustment. The
retaining clip is then installed back onto the throttle
valve cable to lock in the adjustment.
A correctly adjusted throttle valve cable will cause
the throttle lever on the transmission to move simultaneously
with the throttle body lever from the idle
position. Proper adjustment will allow simultaneous
movement without causing the transmission throttle
lever to either move ahead of, or lag behind the lever
on the throttle body.
|
With that being said, I often found it difficult to adjust the TV cable, I never knew really which one it was (I originally mistakenly adjusted the speed control cable), how to adjust it, and when to know it was right. So, now that I've figured that out, I thought I would share it in detail for future folks.
This adjustment can be done in under five minutes, and I actually have it down to under a minute now, hood up to hood down.
First, here is a picture of the Throttle Body, but I've altered the image to give you a good view of the TV cable specifically.
The idea is to get the TV cable to move the throttle body lever to move at the same time as the transmission throttle lever. You can accomplish this two ways: one requiring a buddy, one that doesn't.
First, unclip the black retaining fixture on the end of the TV cable.
Second, release the black plastic clip that is holding the TV cable to the metal bracket. To do this, you simply squeeze both sides of the black clip and slide the clip backward through the bracket.
Now, here's where the adjustment comes in. Next, you
gently pry off the white retaining clip with your nail or a small flathead screwdriver. You'll notice the cable retracts a bit with the clip off. The idea, as previously mentioned, is to get the throttle body lever (the arm that was attached to the first black clip you removed) to move in sync with the transmission throttle lever. To do this, you can either have a buddy watch one lever while you move the other, ensuring the levers both start at the same time, get to the middle at the same time, and end at the same time.
Or, you can do the old trial-and-error method and simply take it for a spin after each go around. Either way, it's quick and easy.
With the retainer clip removed, adjust the cable in or out to your desired length/tension. Once the appropriate cable position is reached, rescuer the white retainer clip.
Then simply follow all the steps in reverse to reassemble the cable. Now, take her for a test drive and see what you've got!
Here is the official adjustment text from the FSM if my version is too hard to follow.
Quote:
Checking Throttle Valve Cable Adjustment
(1) Turn ignition key to OFF position.
(2) Remove air cleaner.
(3) Verify that lever on throttle body is at curb idle
position. Then verify that transmission throttle lever
(Fig. 178) is also at idle (fully forward) position.
(4) Slide cable off attachment stud on throttle body
lever.
(5) Compare position of cable end to attachment
stud on throttle body lever:
² Cable end and attachment stud should be
aligned (or centered on one another) to within 1 mm
(0.039 in.) in either direction.
² If cable end and attachment stud are misaligned
(off center), cable will have to be adjusted as
described in Throttle Valve Cable Adjustment procedure.
(6) Reconnect cable end to attachment stud. Then
with aid of a helper, observe movement of transmission
throttle lever and lever on throttle body.
² If both levers move simultaneously from idle to
half-throttle and back to idle position, adjustment is
correct.
² If transmission throttle lever moves ahead of, or
lags behind throttle body lever, cable adjustment will
be necessary. Or, if throttle body lever prevents
transmission lever from returning to closed position,
cable adjustment will be necessary.
Throttle Valve Cable Adjustment Procedure
(1) Turn ignition switch to OFF position.
(2) Remove air cleaner if necessary.
(3) Disconnect cable end from attachment stud.
Carefully slide cable off stud. Do not pry or pull
cable off.
(4) Verify that transmission throttle lever is in
fully closed position. Then be sure lever on throttle
body is at curb idle position.
(5) Insert a small screwdriver under edge of
retaining clip and remove retaining clip.
(6) Center cable end on attachment stud to within
1 mm (0.039 in.).
NOTE: Be sure that as the cable is pulled forward
and centered on the throttle lever stud, the cable
housing moves smoothly with the cable. Due to the
angle at which the cable housing enters the spring
housing, the cable housing may bind slightly and
create an incorrect adjustment.
(7) Install retaining clip onto cable housing.
(8) Check cable adjustment. Verify transmission
throttle lever and lever on throttle body move simultaneously.
|
>
Throttle Valve (TV) Cable Adjustment
