Help Needed

[goatcheeser]

Greetings,

I own a 1994 Sl1 with a little over 75000 miles on it. Lately, I have been having problems with the car overheating when idling, and/or when I am stuck in stop and go traffic. I had someone tell me to replace the thermostat and am doing that today. However, the overheating is not my main concern. This is where it gets weird and I hope you are able to follow my explanation of the problem. Whenever the car would overhead, my check engine light would come on and the car would not shift out of first gear; it would just rev to about 4000+ revolutions per minute and then sputter when I took my foot off the accelerator. I have never had a problem fixing this. All I have to do is turn the car off and restart it. Not only does restarting the car remove the check engine light, but it also seems to fix the shifting problem. I thought the problem was directly related to the overheating, and it might be; however, someone suggested I could keep the temp. down by running the ac; this helped with the temp., but I still had the same check engine light and problem shifting after being stuck in traffic again. I did recently have a a leak in a spark-plug well. I changed the plug and the gasket but did not change the spark plug wire, also being fixed today. I recently had to change the top engine mount, but it took me a while to diagnose the problem so the engine was regularly shaken for a spell. Thank you in advance for your help.

-Goat

[MadPuppy]

I think the coolant temp sensor helps control shifting in automatics, it may be that the overheat tripped the sensor and the sensor would not let the PCM get the trans out of 1st gear. I would consider fixing the overheat condition and/or replacing the coolant temp sensor.

[el diablo viejo]

You have two sensors, one for the gauge with a single wire connector, and one for the pcm with a two wire connector, which is the one you want to change. They are both on the the driver's side of the head, just take off the intake air tube to gain access. This is always a good place start. You should also read any stored OBD1 codes and post them here.
Have you read this http://www.saturnfans.com/forums/sho...d.php?t=177672 ?

[fdryer]

Replace the original two-wire coolant sensor. This sensor indirectly causes xmission shift issues when the engine computer is given incorrect coolant temperature signals. Replacing the faulty sensor will correct the overheating problem.

[goatcheeser]

UPDATE:

I want to start by thanking you all for your help. I decided to put off replacing the thermostat. Many of you have suggested changing the cooling sensor. Replacing the sensor seems like an easier fix than draining my coolant system to replace the thermostat. Yesterday, I was given the wrong sensor and am now waiting for my car to cool down before attempting to replace the old sensor with the correct part. I am a bit concerned because I did remove the old sensor to see if there was any noticeable damage, there wasn't. This is slowly becoming a cluster and am starting to fear that I may just have to bite the bullet and take it to a professional. I will be sure to update once the new sensor is in. Thanks again.

-Goat

[alordofchaos]

Was the tip on the sensor you pulled out flat, or rounded?

When you turn the AC on, the engine fan should come on full speed. Does it do that?

[goatcheeser]

It is rounded and yes, when I turn the ac on the fan does come on.

[screwpid]

Originally Posted by goatcheeser

It is rounded and yes, when I turn the ac on the fan does come on.

Sounds like you need to upgrade that sensor to the copper one thats flat. That sounds like the oem temp sensor. You should have changed that last year! Paperclip your car and post the code you are getting.

[Sc86gt]

.....

[goatcheeser]

Update:

Okay, I replaced the round sensor for a newer flat one. So far, I have not had my check engine light come on. I idled my car until the fan came on around 3/4 on the temp. gauge, then drove around, no problems. Not sure if I "paper clipped" the car right but on the check engine flashes I got 14 and then the low coolant light flashed 22,23, and 24. Again, I am not a hundred percent sure I did the diagnostic correctly. Thanks

-Goat

[fdryer]

This link can be helpful for exact information; http://www.differentracing.com/tech_articles/index.html

Keep in mind one general rule while getting lost in diagnostics and interpreting error codes whether its OBD I (yours) or OBD II (after '96); if the engine runs without misfiring, the engine's fine. If xmission shifts are ok along with the engine running smooth, the xmission being controlled by the pcm is probably fine too. A simple failure of the original two-wire coolant sensor has caused more engine/xmission problems than any other sensor. Beware of manually resetting the pcm to clear error codes; resetting manually clears emissions parameters back to factory defaults and requires the car be driven a minimum of 50 miles to learn how to shift as well as establish new emissions parameters, some cars may not run or shift correctly for the first twenty miles or so and may mislead anyone jumping to conclusions of more problems when not familiar with EFI systems using OBD I or OBD II.

[goatcheeser]

A week later and my car is still having the same problem in traffic. I thought I had the problem fixed and had not received a single check engine light. Now, today, the light came on, and I couldn't shift my car again. Any suggestions?

[alordofchaos]

Originally Posted by goatcheeser

A week later and my car is still having the same problem in traffic.

Did your fan turn on when the car overheated?

We know the fan works now, since it came on with your AC.

If the fan did not turn on when your engine got hot, the next suspect is the ECTS connector (esp if there was any corrosion). It uses the same connector as the IAT sensor, so a JY should turn up a good one for a buck or so.

Also, make sure you have a healthy return stream from the hose at the back of coolant surge tank/reservoir when the car is warm

Wait, just re-read the original post to see if I missed anything - maybe someone who is more familiar with Throttle Position Sensor issues can chime in, but doesn't the high RPM that resets after restart sound like a TPS issue? Assuming the car still does this?

it would just rev to about 4000+ revolutions per minute and then sputter when I took my foot off the accelerator. I have never had a problem fixing this. All I have to do is turn the car off and restart it. Not only does restarting the car remove the check engine light, but it also seems to fix the shifting problem.

[goatcheeser]

@alordofcaos, Yeah, the fan comes on fine; I am starting to think this was never a cooling issue and it is just coincidental that the problem happens when the car runs for an extended period of time. Here is the kicker: it never happens when I go on long trips. I have done 6 hour trips recently and never had a problem, presumably because I was constantly moving. The problem only happens when I stop, then go, then stop, then go etc.. Whatever it is, it directly affects the transmission until the car is restarted. The high revs are occurring because the transmission is not shifting properly. Anyone in the market for a used saturn?

[goatcheeser]

Could it be a bad speed sensor? I have noticed that my cruise control does not consistently work.

[fdryer]

While there may be a repeat of error codes, be sure by retrieving them and post what you find. Assuming anything can mislead anyone.