1993 SL bucks... suggestions?

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

M. Cantera wrote:

"K. Daver" typed until their fingers bled, and came up with:

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 aga> Probably the ECM.

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:

to Diagnostic Trouble Code Information, and Diagnostic Trouble CodeChart for 1st Gen Saturns. Since you have a 1st gen Saturn, you can do itwith a paper clip. Or, I've heard that you can stop by any Auto Zone andhave 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

Philip Nasadowski wrote:

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

1. 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)

hoosier_drifter wrote:

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

Mike wrote:

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 > I find it funny that people have to make suggestions to their mechanics and

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

K. Daver wrote:

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.