Just *inherited* a '94 sl1. Neat little car. It had been sitting in a field for the past 2 years so it needed a bit of work. Initially, it was parked because it overheated.. They never got around to fixing it so.. there it parked.

I got the car, drained the gas, changed the oil, replaced brakes and rotors all around and I drive it for work :-) Neat little car!

My random questions are these...
1. Initially, the Radiator fan wouldnt kick on. Relay is good. Fan turns on when jumping the relay. I replaced the Coolant switch and immediatly, the fan kicks on. After replacing the sensor though, Now i have a low coolant light (least i think its a low light) and as soon as the light turns on, the fan kicks on. Not *entirely* a problem except its winter and it takes forever for the car to warm up with the rad fan on non-stop. Also, parked it cools to practically cold again.

Is the Sensor i put in bad or is there a sensor in the resovoir that i'm just not seeing?

2. It hates cold starts and sputters and dies.. I have to keep my foot on it. IAC right? Is cleaning them worth it or just replacing it?

It runs pretty strong when its warmed up. Kinda has a bit of top-end knock though.. :-/ good thing i got it for free. (save for the ~400 bucks i put into making it run again)

-Justin

 

Welcome to the forum, Justin. To answer one question, yes, there is a sensor in the bottom of the reservoir. They get funky and most times you can clean them and take care of that light. As for the cold starts, you may want to start with some new plugs and wires. Old wires have a LOT of resistance, especially in cold weather. And finally, you probably need to replace the ECTS with one from a GM dealer and NOT your local Autovancereilllynapa. You need a brass tipped one along with a new pigtail. Costs will be between 40 and 50 bucks for both, but well worth the investment. The 1.9 SOHC is a solid little engine and doesn't use oil like the DOHC. You DO need to check the oil on a regular basis, but not ever couple of days. I used to check mine on my SC1 every two weeks and it never used more than a half quart between oil changes of 5,000 miles. The DOHC I had was a totally different story. It loved oil.

 

+1

New ECTS from GM plus wiring harness. Aftermarket ECTSs for these cars suffer calibration issues. ECTS has huge influence on air/fuel ratios. It's probably responsible for both the hard starting (you should only have to wait for the fuel system to prime, then turn the key without ever touching the gas) and the knocking (air/fuel ratio calc'd at wrong temp).

The fan should not come on immediately on starting.

My guess is that the ECTS in there is actually shorted (essentially 0 resistance, corresponding to HIGH HIGH temperature, and a bit rare, they usually fail open circuit) so PCM thinks engine temp is crazy high as soon as you turn the key.

That would explain why it's running in the winter at startup; the PCM thinks the coolant is at some very high temp--ALL THE TIME. I don't think the coolant light is triggering the fan, but I may be wrong as my PCM never had to deal with a shorted ECTS, so I don't know what the PCM commands when the temp is super high.

Given the age of the car and the dry rot condition of the plastic under the hood, you may wish to buy a replacement reservoir w/ sensor -- the sensor alone cannot be pulled and replaced.

Please come back and let us know what was what and what is now what.

 

Moved to S Series Sedan section from L series

 

I believe that sensor is a fail safe type, meaning that if it fails, it turns on the fans just so the engine will be safe. It is not the cause of the engine taking so long to heat up though, that is your thermostat. Thermostats tend to fail open, that is they will remain open, or partly open when cold and that causes the engine to take a long time to warm up. In winter, they will often not warm up at all.

Since it sat for so long, I would remove the top timing chain cover and pour some oil over that chain and let it soak good. Then turn the engine slowly and look for any stuck links, those that do not want to flex easily. If you find one, soak it in penetrating oil like seafoam or PB Blaster until it works loose or else the chain will eventually break.

 

Keith,

If you pull the ECTS connector off, (no sensor = failed sensor=-40 reading inferred by PCM), I don't believe it turns the fan on. If it did, all those folks with failed ECTS' s (open circuit) would not have their cars overheating, As far as I know, the PCM sends a command to close the fan relay based only on the temperature reading it infers from the resistance of the ECTS. There are ECTS codes but I've never seen one trigger on an s car.

As for slow heatup, ya--I kinda overlooked the most obvious reason for that ---thanks for correcting that blunder..

 

Derf, I sold my Saturn and gave all the books to the new owner so I don't all the info, so you are probably right. I was thinking about most cars in general that use a sensor located in the bottom of the radiator that controls the fan, but now that I think about it, I did have to pull the radiator once because the drain valve broke when I was doing a coolant change and I don't recall that sensor in the radiator.

If the bad sensor/no sensor code does not turn on the fan by default, then GM made a huge design error. Almost all, if not all other manufacturers use the fail/safe logic to protect the engine.

 

Keith,

I know there are OBD codes for thr CTS (coolant temp sensor)---but they never seem to pop--that's why so many failed ECTS's lead to overheating.

I wouldn't be the least bit surprised if the system is designed as fail safe once one of the ECTS related codes pops --but they never seem to. The problem is that the calculated temperature is -40, but that is considered "in range" as far as temp readings go, so the "ECTS out of range low" will never pop.

Frankly I can't remember what happens if you remove the ECTS wiring harness.

crazyman -- please try unplugging the ECTS squeeze connector and let us know what happens to the fan behavior and whether it throws a code, and which one if it does. Then plug it back in, of course.

 

Sorry to take so long to get back. I just had a new kiddo and sleep and work has been.... interesting.

I did spring for the napriellyautozone temp switch and as soon as I installed it that light came on. I started chasing other things thinking the light had to have something else causing.

I just pulled the code, 14 and 15 came up. (Along with the normal 12) I just went through emissions and the car did fail due to to high CO - likley due to that sensor I'm thinking...

3rd party sensors can't be *that* bad.. right? Why would they sell them I'd the didn't work? Any idea how I could calibrate without replacing it?


-Justin

 

Unless you can split it open and change the thermistor and put it back together, no.

This is EXACTLY why we harp on the need to use the GM ECTS and connector.

SPECULATION:

The connector you bought is probably manufactured in a plant that buys cheap thermistors that are considered OUT OF SPEC by THEIR high volume customers (the thermistor company's customers)-- meaning they don't meet the accuracy spec they are designed for.

The company incorporating the out of spec (reject) thermistors into coolant temp sesnors doesn't give a **** as long as they have customers lined up to buy them who either don't know or just don't care (most auto part brick n mortar chain stores). They offer a subpar product at a lower price than the dealer with no information about its specs.

You buy it
They make money
You install it
It behaves wrong because it was built from crap components and it always will.
Of course, sometimes you buy an aftermarket one and it is close enough.

When people join this forum citing drivability issues, the FIRST question we ask is "have you ever changed your ECTS?".

Hard starting, no start, crap gas mileage, improper air/ fuel mix leading to failed emissions, hesitations, aux cooling fan never coming on leading to overheating........

This sensor's response is involved in so many aspects of engine management.

Codes generated by installing substandard parts are not worth troubleshooting
Get the right parts. Install them. THEN we have a chance to help you out.

We have a sticky for it, but it needs revising so I never point to it.
Maybe I'll take SOME of the text from this post or maybe even the whole thread as an example of what CAN happen when using certain aftermarket parts in certain šcan spell the difference between success and failure.

(OK Big Shoes, I'm gettin down off my ECTS Preachin' High Horse )
_________________
Now that I'm off the ECTS horse, here's a non-Saturn example.
2005 Chevy Silverado 1500 5.3L V8
Codes: Knock Sensors 1 and 2, low circuit response (something of that nature).

These engines have a design flaw that allows moisture to condense and collect in the wells in which the knock sensors reside. The sensors then rust out and stop functioning. The top of the engine must be removed, the sensors replaced rtv bead surrounding sensor well to block water, intake manifolds redone. NOT CHEAP. DIY job so just homegrown labor.

Did replacement w off brand sensors. No codes re-thrown until above 65 mph.

Dug further into internet to find multiple posts stating "you have ZERO chance of "solving" this problem unless you use the AC Delco replacement part."

The other brand apparently has a different response curve.
Bummer -- cost us twice in parts.

Lesson: Do ALL your homework before you embark on an underhood quest for the answer, and heed the advise of those who have been in your shoes.