98 SL2 Auto Trans Shifting Problems

Whenever I take off from a stop, my car seems to hesitate shifting into
the next gear (i.e. it takes a lot more RPMs make the car shift than it
used to). It also will hesitate to down shift, whether passing or just
coasting down. It will wait so long that when it finally does shift
down, it slams into gear and the car will literally jerk like I've hit
something. I am hoping that these two problems are related and cheap to
fix. Any ideas?


It runs really well and has about 80k miles on it. The only thing I can
think of is a sensor for the transmission going bad (if it is
electronically controlled).

 

There is a switch that can be set to either "economy" or "performance".
Sounds like yours possibly got changed to the performance setting which
winds out the RPMs to develop higher power before shifts.

Bob

 

98's don't have that switch.

 

There's no switch but, I was told by the dealer that the car "learns"
how I drive and makes adjustments accordingly. When I mentioned that I
have not changed the way I drive so the car should "remember" what it
"learned" did not sit well with the mechanic. He told me that "these
cars perform best when driven hard" and that this problem would
disappear with rougher treatment. That was about 8 months ago. This
problem has gotten progressively worse.

Jake

 

I just found out that there is a vehicle speed sensor.
If it is an electronically controlled transmission, could the vehicle
speed sensor could fail over time and not allow proper shifting? Is
that what controls shifting? Or, is it merely for the cruise control?

 

To help in troubleshooting you need to be more clear with the symptoms. Is
the delayed shift occurring only between one set of gears or is it on all
three up shifts (1-2, 2-3, 3-4)?

Bob

 

Under hard acceleration the car does great. You wouldn't know the car
had an issue, I just don't like flooring it all the time. When just
getting up to speed at a moderate pace, the shift from 1-2 is a little
rough, 2-3 is significant, 3-4 is a little better but, there is still a
problem. It seems to forget to shift, then slam into gear. From 2-3
used to be around 35 mph. Now, if I don't take measures to ensure a
shift; it will stay in 2 and 35 will equate to about 2800 rpm. If I run
the car up to about 42 it will shift and I then coast down to 35 and
everything is fine. 35 mph seems to be where I do most of my driving.
But, it doesn't seem to just have difficulty shifting up, down is
awkward as well.

 

I'd start with changing the fluid and filter. See if it improves. These
valve bodies get clogged if the fluid is not changed at regular intervals.
It may also be a solenoid starting to go flaky and open up so not engaging
when expected. It also could be the speed sensor as you suspect as well.
You may need to wait till it dies completely before you can diagnose this at
that level. Are you getting any trouble light and trans codes?

Bob

 

I was thinking the same thing. Changing the fluid and filter is the
cheapest and easiest option and a good starting point. Bob, I could
actually hear the "plunk" that the pockets of thicker fluid made as they
dropped into the catch pan. One interesting thing; the trans filter
off, it was still pretty hot so, I tossed it to the ground after
removing it from the last few threads by hand. When I was finished and
cleaning up I noticed something on the filter, right over the threaded
hole that fixes it to the engine. It was a large and powerful magnet
which, still had some metal shavings caught before entering the filter.
I have never seen such a thing. I wish I would have noticed it before
I finished, it did't seem worth draining all my fresh transmission fluid
back out (not to mention, catch pan already full). I might get some use
out of the fluid in it for a while and change it out again sooner than
the suggested interval, making sure to replace the magnet. The good
news is that like my Dad would have said, "it runs like a scald assed
ape." Which as I understand it, it good.

 

The Saturn spin on transmission filter (looks like a regular oil filter) has
a magnet integrated into the design. As such, it that gets replaced when
the filter gets replaced. This type of filter was a novel idea and in my
opinion is head and shoulders above the filter and magnet in the bottom of
the in the pan design used in nearly every other transmission I've ever
seen.

I also like the fact hat the trans has a drain plug as this makes it a lot
easier to do this job. The reality here is that given the location of the
drain and filter, it is far easier to change the transmission fluid and
filter than the regular oil!

Hope that your transmission continues to run good. I'd plan on changing
that fluid about every 30K miles.

Bob

 

Thank you very much for your help, Bob.