1993 SL bucks... suggestions?

Hey everyone..

I have a 1993 Saturn SL manual 5 speed which has started bucking while
driving. It has about 160k miles on it and has been EXTREMELY
dependable until now. While driving it, it will start to buck. There
doesn't seem to be any pattern except for once in a while it will buck.

At first I thought it was bad gas.. I've replaced that, and it doesn't
seem to help. I remember my girlfriend's Jeep Wrangler bucking and it
turned out to be an oxygen sensor. I'm not sure if this is the same,
but it sure felt like it.

Just wondering what other people with similar problems have found helpful?

The plugs are relatively new and so is the wire set. I've tried fuel
injector cleaner and that didn't seem to help any.

Thanks in advance!

Marty (remove NOSPAM in my email address to reply privately)

 

Could also be the Throttle position sensor, or could be the whole
engine control module in limp mode. Is the weather getting warmer?.

Have the car diagnosed by a competent mechanic

 

Hi there!

Gotcha. Yes -- the weather has gotten warmer. I'm in the East Coast,
and we're just starting to get back to 60'ish degrees.

Thanks for the tips!

Marty

 

also check the torque axis mount (upper engine mount)

 

Probably the ECM.

I had the same thing happen on a 90 GMC truck. It would go for about
five or six miles and thenit would start missing. Took it to the
mechanic on a colder day it it ran fine (had a cold front move
through) Three days later missing again. No check engine light or
anything else.

A different mechic replaced the computer and that cured the problem

 

Thanks for the tips. I hate to just throw parts at it (like I had to
with my girlfriends Jeep..) but will definitely start looking at the ECM
and mounts first.

Thanks again!

 

I'd guess the ECM is giving you problems. If you wanna have it verified
first, be sure to take it to Saturn or at least to someone with Saturn
experience. GM dealership kept trying to screw around with me telling me my
plugs and wires needed replaced (had just replaced them before going.)

Told them this, they checked again, and then told me there was no miss!?
The 'Mr. Goodwrench' character there was fascinated when I pulled off a plug
wire and showed him the miss in action against the valve cover. He had
literally never seen that done before! Scary. Sometimes I wonder if
warranty work is worth the risk.

Anyway, I told them that it had to be either the ECM or coil pack, and to
check them. They came back with, "we think it's both." In other words, "We
don't have a f%^# idea of how to check, so we're replacing them both!"

Good news is, if the ECM is the problem, most places sell the ECM and coil
pack together as a set. So, it's hard to go wrong with it. Look for a miss
on a cylinder, check the wire for good continuity, and if the wire is good
and it still misses....probably the ECM going down. Warmer weather kicks
this problem into prominency.

 

I would be AMAZED if the computer were the problem. I've never heard of one
going bad.

You should read the codes from the computer to see what's up. Until you do
that, you can do a lot of guessing and start replacing parts, but it doesn't
guarantee that it will fix anything. You can see instructions on how to
read the codes yourself here:

http://www.differentracing.com/tech_articles/index.html
Refer to Diagnostic Trouble Code Information, and Diagnostic Trouble Code
Chart for 1st Gen Saturns. Since you have a 1st gen Saturn, you can do it
with a paper clip. Or, I've heard that you can stop by any Auto Zone and
have them read the codes for no charge.

Any Haynes or Chilton manual will give additional info on what each code
means.

Good luck,
Lane [ lane (at) evilplastic.com ]

 

Me too.

The electronic ignition pack could go bad, and I've had that, but not on
my Saturn.

Don't forget - the crank sensor could be acting up.

Garbage in, garbage out.

BTW, I know as a fact that at least one aerospace firm has approached
the Big Three to share info w.r.t. computer hardening. Automotive
environments are apparently pretty brutal, and said firm was looking to
compare notes with said Big Three company to see if they could learn
anything new...

I'm currently specing out a data aquisition system for a customer. One
requirement is that it's hardened against shock waves from explosions.
No kidding, the computer will be installed near 200kv class circuit
breakers. When those trip, it's not pleasent at all. Doubly fun
because it's a RR traction application, and that means all sorts of
bizzare stuff you wouldn't see in a transmission application....

 

Again, MANY MANY thanks. Once I'm able to bring it to my mechanic, I'll
let ya know.

Appreciate the help!

Marty

 

You can get the codes read for free at autozone and pick up any parts you
need at about as cheap as you'll find anywhere. One trip, possible
solution.

As to ECMs going bad...
They don't go bad on their own very often; that much is true. However,
other factors can lead to them failing due to stress' inflicted by poorly
done maintenance, broken casings, other bad parts, or when they do have
problems it usually happens with increased heat that triggers expansion.
The expansion causes defects in materials or poor assembly to come apart and
loose conductivity. This happens even in military grade ICs and components,
and as an engineer and technician I've seen plenty of these 'rare'
ocurrences.

I'm not telling you to go straight to swapping parts, I'm telling you to go
to an 'experienced' mechanic/technician with Saturns to have it checked on,
or read the codes at Autozone for free and take a stab at fixin' the
situation yourself. That is all! The ECM/coil pack experience I had was
just an antecdote, harping on a few Mr. Goodwrench guys at Kenny Kent in
Evansville, IN...
PS... I know some good mechanics there as well, but Larry, Darrell, and
Darrell there soured me a bit.

 

Ok gang... Here's the deal:

Went to the mechanic (he specializes in GM and I trust him
wholeheartedly)... although he's not a specific Saturn mechanic. We
(and by WE I mean HE) read the codes and it popped up with a 53 and a
45. He wasn't sure if they had not been cleared, or if they had been
caused, by a previous dealership visit. So, he cleared 'em anyway. We
changed the O2 sensor. The jerking and "misfiring" still happened. We
(HE) checked the codes again, and nothing popped up on the computer.

I'm going to drive it for a few more days to see if anything will pop up
on the scan tool. Any ideas on what the code 53 is? He thought it was
the computer and the 45 was the O2 sensor.

I searched on code 53 via Deja and someone, a while ago, posted it as
being ECM related on a 1991 or 1992. As this is a 1993, I didn't know
if that still applied.

Thanks again everyone!

Marty (remove NOSPAM to reply privately)

 

No personal experience with it, but - Here is what my OEM 91-94 Electronic
Engine Controls manual says about code 53.

Code 53 will set if the PCM is unable to eliminate engine knock by retarding
timing. (i.e. the engine noise is most likely not due to spark knock) It
does not indicate a faulty knock sensor. Most likely causes Valve lifter.
Belt Tensioner. Loose Bracket. Low Octane Fuel in high Ambient temps while
pulling loads. Piston/Cylinder scuff.

Once the knock condition is corrected, the code 53 should be erased by
disconnecting power to the PCM- it does eventually learn back the '0'
condition, but is a very slow process. (paraphrased)

1991, 1993 and 1994 the PMC also relies on coolant temp in order to select
the correct spark retard value table (they specifically leave out the 1992
in this statement).

Maybe some of this can set you on the right track to finding your problem.

 

Mike,

AWESOME. Thank you very much for posting that! I'll forward that to my
mechanic and post the results.

Again, MANY MANY thanks..

Marty

 

I find it funny that people have to make suggestions to their mechanics and
tell them what to look for, and see nothing wrong with it.

After all, you don't usually go to a doctor, who sends you home saying he
doesn't know what the problem is, only to do research on your own to visit
him again in order to tell him what the diagnosis is. Most of us would hope
that his education, training, and experience would make him able to do that
without our help.

If it were me, I'd find another mechanic who has factory service manuals for
the car (where it sounds like the info below comes from) and the ability to
use them. Sounds like this guy does not.

Lane [ lane (at) evilplastic.com ]

 

Not at all... very competent. He's just a friend of mine who is a GM
mechanic and teaches other classes (non-auto related) at night. He
doesn't do side work and isn't a specialized "Saturn" mechanic. So,
because he's doing it on his time, and not charging me labor, I try to
take care of as much as possible before bringing him the car, telling
him to drive it around for a week, and saying "fix it!" if the problem
resurfaces.

He does the same when he has a computer problem. Writes down all the
codes, glitches, etc., before he dumps it on me. Not that we don't know
what we're doing, but we don't have a lot of time to sit there and try
to "restart" the problem ourselves.

Just a matter of each one helping the other out due to our schedules...
nothing wrong with that...

 

Ok,

Here's the update: The mechanic cleared all the codes (I think it was
45 and 53) to see if my recent trip to the dealer caused any to trip
(had to have my ignition switch repaired in an emergency).

I ended up replacing the O2 sensor and the fuel pump. Both had been the
original ones since I bought the car (and had never been changed with
the previous owner). The codes never came back after he cleared them
from the computer, but the car still bucks.

Any suggestions? We're thinking to try putting a new wireset (although
we did change them before [for maintenance, not anything "wrong" persay].

Thanks again everyone!

Marty

 

If you think that there might be arcing, you have to replace the plugs and
the wires at the same time.

Why, you ask? Because if there is arc tracking along the plug wire and the
plug, then replacing one and not the other will still provide a pre-burned
path for the arc track to reestablish.