1993 SL1 Manual Is "Jerking"

Hello everyone.

I found this newsgroup and hope that others can help. I saw that some
others have had similar type problems so I attempted to fix most of
those that I could.

I have a 1993 Saturn SL-1 (manual transmission) with just under 165k
miles on it. It's been a very reliable car, until now.

I've noticed that while between 1500-2000 RPM (in any gear), the car
will begin to shake (sometimes violently, sometimes slightly) when
slowing down. It may happen at other RPM's, but 2000 RPM seems to be
the "start" of it. The weather conditions (I'm in New England) don't
appear to affect the performance or frequency.

There is no service engine soon indication. I've replaced the spark
plugs and wire set, replaced the fuel filter, air filter, and oxygen
sensor. Neither seemed to help diagnose or correct the problem.

I called Saturn and they told me that it could be a "bunch of things"
and that I could bring it in and they'd try to diagnose it. At $80/hr
here, I'd rather not have them throw parts if they aren't sure. Getting
a new window regulator from them was hassle enough!

The car is regularly serviced and well maintained.

Any suggestions? (remove "NOSPAM" to reply privately)

Thanks in advance!

 

More detail in describing the problem and some basic troubleshooting would
help us to provide a few possible causes for you to check. For instance,
you say the car shakes while "slowing down" in any gear... Is this possibly
related to your brakes (warped front disc rotors?) or does it occur while
"coasting to a stop" without application of the brakes? If not the brakes,
does it happen if the vehicle is in neutral which would indicate a
suspension or steering problem? If only when the engine is engaged to the
transmission, then let us know that as well.

I'd guess brake rotors and possibly front suspension. You need to either
take it in for diagnosis or troubleshoot it more and provide details here.

Bob

 

Hi Bob!

Thanks for the reply.

Sorry! I knew I forgot about the brakes... New rotors (had the problem
before and after), and brakes are good as well. Mechanics didn't think
that was the problem when I asked him, though.

It's hard to describe the shaking the car is making. For example, on
the way home from work, I depressed the brake slightly after being in
5th gear... the car did it's violent shaking thing. Almost feels as if
the engine is knocking back against the car. I didn't have the cluth
depressed while I was slowing down. The brake wasn't being pressed
hard, either. It seems to start exactly at the 2000 rpm mark, though.
That part, at least, is consistent.

I don't remember if I've noticed it happening in neutral. I will try
tomorrow on my way to work. I also seem to remember that when the
clutch is pressed, it's not as noticable. Although, I will retest this
as it's been so "normal" to experience this, I'm kind of used to it.

Thanks again!

ML (remove NOSPAM to reply)

 

Bob (and group),

I tried paying better attention to the characteristics. It seems as if
I'm slowing down (with brake, not just coasting) and I am in gear, the
jerking will be present. The RPM's drop drastically (to way under 1000)
when I am not in gear and slowing down -- but the jerking is not present.

So, it would seem that this is happening only when the engine is engaged
in gear.

Something I also noticed was that sometimes at idle, or when starting
from a stop, is that the RPM will sort of spike up to about 2100 and
then back down to close to 0. This doesn't seem to happen with any more
than a light press on the gas and doesn't repeat all the time.

I'm all ears... any ideas?

Thanks again! (remove NOSPAM in my email address to reply privately)

 

check your top engine mount (Torque Axis Mount). If the rubber is torn,
replace it. $35 at Advance Auto.

 

I'm still not sure I fully understand the conditions causing the jerking.
Seems you need the engine engaged AND the brakes applied. I'd still be
thinking badly warped front brake rotors as the most likely cause. I'd
suspect the top engine (torque axis) motor mount as a possible cause as
well. These are all easily replaced, but you need to do more
troubleshooting and diagnosis to determine which is causing your symptoms.

Bob