1999 Saturn Rough Intermittent Hard Start/Rough Idle HELP needed PLEASE
 

This is my first post here so I would like to first say Hello to all, and Thank You in advance for any time spent to reply.

The car- 1999 Saturn SL with DOHC engine/Manual Trans

The problem- The car has 102k miles on it and recently started this intermittent hard start/rough idle. When this happens it puffs a raw fuel smell out of the exhaust.

The car was due for new spark plugs at 102k they were original. So I replaced them, I also cleaned the throttle body, Cleaned the K&N Air Filter, Replaced the Fuel Filter, switched to Ethanol Free Fuel and the problem still happens.

I know for a fact that the Coolant Thermostat is stuck open and needs replaced still along with needing new coolant.

I have read somewhere that the Coolant Temp Sensor can cause this issue as well. Should I replace the coolant temp sensor and install a new thermostat as well?

I bought the car with 60k miles on it and I am fairly sure that the only repairs to the car so far have been done by me. The car does NOT show any Check Engine Light so I am just guessing and throwing money at it.
I really need help here because I am out of cash and cant afford to take the car to a dealer. I use this car to drive 20 hours round trip to visit my ailing grandparents, without this car I cant afford to make the trips.

Please help........:(

If the stat is bad and the engine does not come up to operating temp thats not a good thing. The ETCS will cause this sort of problem as stated 1000 times over the last 20 years on Saturn forums. Replace the ETCS and it's connector. Buy both from your local Chevy dealer thats selling SATURN parts. Do not buy from PetesParts&PlumbingSupply. As for the spark plugs be sure to use NGK and only the proper NGK plugs.

Welcome to the Saturn Forum. Go up to the new member area and introduce yourself.

Yes Sir,
I did replace the spark plugs with NGK plugs and properly gapped them as well.

I will go ahead and replace the ETCS and the Thermostat as well. I will look now for a local dealer for availability.

Is there any resistance checks or voltage check I can do on the ETCS to confirm its problematic before replacement?

Thank You Very Much, I appreciate the knowledge and your time spent to reply.

+1 goes out to RjION for his wisdom and advice ..........

Also, welcome to Bobbed06 to the Forum .......

Thank You, I am glad to be here....

To Bobbed06 --

Yes, you could do a resistance check on the part, but remember, it is a negative varience device ... as the temperature rises, the resistance falls.

Measure before you start the car, and let us know what you read -- oh, and tell us too, what is the temperature of the weather at your place?

OK, I can do that. Yesterday when it happened it was about 50 degrees.

I will not be able to provide a cold resistance measure until late tonight, since I have the car at work and will have to drive it home before I can do the test. Then I will have to let it sit for a few hours to cool off.

I appreciate the help so much. Thank You

I just located a Saturn Dealer and he said that he has both the ECTS Sensor in stock.

ECTS Sensor $18.34

Connector $27.23

Be sure you change the connector with the ETCS is all I have to say.

I will be sure and change the connector also. The car has not had a chance to sit and cool off this evening but it did do the problem again.

It started fine when fully cold after sitting all day at work. Stopped at the store and let it sit for a half hour or so, and sure enough it started rough and idled roughly for about 7-10 seconds.

It starts normally when fully cold, like in the mornings or after work.

I think I will just skip the resistance test and just replace the sensor and connector.

Thank You for your help.

This sounds very similar to the problem I was having with my 98 SL2. I replaced the thermostat because my car wasn't getting warm and the ECTS. I also had to replace the O2 sensor after driving the car for about 60 miles. My car had been running rich for about a year or more and wiped the O2 sensor. It appears that my car is now fixed. Here is a link to my post.

https://www.saturnforum.com/forum/saturn-s-series-sedan-27/new-forum-questions-about-sl2-6564/

Well tonight after work the car would not start. It was so flooded that it could not start.

So I pulled the injector fuse and it immediately started until it ran out of fuel in the cylinders. I then reinstalled the injector fuse and it started up although it still took several seconds to clean out the cylinders of the fuel.

I was able to get an extra $55 bux on a side job today so I have the cash for the parts. I will be installing a new ETCS and connector along with a new thermostat and coolant flush tomorrow.

OK, i installed the Genuine Saturn ECTS and Connector. The sensor was plastic tipped and all cracked up. The connector was corroded as well.

I went ahead and flushed the coolant system and installed a new Thermostat and gasket to fix the stuck open OEM thermostat.

The car started nicely and once I burped the coolant system and verified the upper and lower hoses were getting warm I drove the car for about 15 miles. Sure enough the SERVICE ENGINE SOON light came on which you had warned me about.

So my question is should I just replace the Oxygen Sensor or should I see if the local Advance Auto Parts store can pull the trouble code? Or can I pull the trouble codes somehow?

If the Oxygen sensor is bad can I use a replacement from Advance Auto or do I need a Genuine Saturn replacement part as well?

Swing by an AutoZone, O'Reiley's, etc and let them run a scan. Post the NUMBERS here, and we'll go from there ....

Since I was out of cash to spend I disconnected the battery, and removed the 02 Sensor. It had some carbon on it and I wire brushed it off, applied anti- seize on the threads and reinstalled it.

I have driven the car 40 miles since I did this and the Service Engine Soon light has not came back on.

So far the car seems to be starting well and idling noticeably smoother and right about 900 RPM.

I will follow up with an update.

I want everyone who posted so far offering assistance that I appreciate your time and knowledge very much. I am a member of several forums and this has been the most helpful and welcoming forum I have ever been a part of.

If you do end up needing a new front 02 sensor, go with a Denso replacement, not a Bosch. (personal experience)

OK, I will make a note of that.

Thanks for posting back and letting us know what you've done. Sometimes people get solutions and just disappear.

Yep, I know and then when someone else has the same problem they are left wondering what the actual solution was.

I will be sure and keep this thread updated so future readers know the start to finish.

Day 5 since I installed the new Sensor,Thermostat, Flushed Coolant, and Wire Brushed 02 Sensor.

Car is starting nicely, Idle is noticeably improved and smoother, Gas mileage seems better although I have not confirmed exact MPG.

I was getting about 39 MPG on Road Trips prior to the problems. However the Thermostat has always been stuck open since I have had the car, and was running on all original tune up until 100k miles.

I would suspect I should gain several MPG now with the fresh Fuel Filter,Spark Plugs, Thermostat, Coolant, ECTS, Air Filter, Clean 02 Sensor, and Clean Throttle Body.