97 SL2 rough idle on cold startup.
 

Hey guys, hoping somebody who's experienced this problem can help me out. I have a 97 SL2 that struggles to idle for a few seconds when I start it cold. Within 3 to 5 seconds, the idle levels out, but then when you push the gas it tries to choke it out. It doesn't quite die, but gets pretty close. Once again, do this 2 or 3 times and everything is back to normal, you can then drive the car with no issues, as far as I observe. There is no check engine light, but I hooked up a scan tool and the only abnormal reading was the fuel trim, which read 150% at idle. I've tried the MAP sensor, and the pressure regulator on the fuel rail... still does the same thing. Any suggestions?

Personally, I'd replace the Engine Coolant Temperature Sensor (ECTS), along with the electrical pigtail that connects it. Cost is about $45usd. Get OEM parts, as after-market ECTS are not very rugged. Make sure the tip of the new part is metal, not resin. Use Teflon tape or paste on the threads, and do not overtorque

About how tight should new one be set to when replacing old ects?

At the risk of sounding ridiculous, I'd say --> "tight enough so it don't leak" <-- but that's not really your question. Remember, you are mounting the sensor into a cast aluminum block, so I'd error on the side of caution. Don't forget the Teflon tape/paste and start about 10 inch pounds, and creep up until it stops leaking.

It's kinda like what Olivia Newton-John told John Travolta in their song near the end of their hit movie, "GREASE" --> "Feel your way"