1997 SL2 Idle Cylinder Miss...

After my '96 finally kicked the bucket with 240,000 miles i picked up a 1997 saturn sl2, one owner with 90,000 original miles.... She sat for a while obviously, bug garaged none the less.

At idle, when i put the car in drive or reverse, she *sometimes, but alot of the times tends to spit and run rough. Sometimes to the point in stalling out. with the slightest amount of throttle... again slight, she will idle fine with no problems, no missfire.

It is also getting only 20 mpg currently... Should be more? my 96 sl1 manual trans got 35-36. I was begining to think AIC? possibly sticking? She sat in a garage for 5 years, untouched... as far as fuel consumption... The temp gauge is reading only about 0-1/4 consistantly, where my 96 was always around 1/2. Faulty temp sensor? enrichening the mix thinking it's colder than it is?

I'm just throwin out ideas.

Thanks in advance,

-Ryan

I would begin by removing and cleaning the throttle body paying attention to the IAC passage and pintle. Next, I would replace the thermostat and the ECTS (coolant temp sensor) and connector. There are two of them. One with a single wire is for the gauge, the other is the ECTS and has two wires and tells the PCM the engine temp. It's very important on newer cars that they run at the proper temp and running at a lower temp can waste fuel.

I would begin by removing and cleaning the throttle body paying attention to the IAC passage and pintle. Next, I would replace the thermostat and the ECTS (coolant temp sensor) and connector. There are two of them. One with a single wire is for the gauge, the other is the ECTS and has two wires and tells the PCM the engine temp. It's very important on newer cars that they run at the proper temp and running at a lower temp can waste fuel.

I'd first replace the ECTS and then the thermostat if the ECTS doesn't fix it. There is only one temp sensor on 1996+ Saturn S-Series.

Today I replaced the ECTS, as well as the intake manifold gasket, egr gasket, and removed and cleaned the throttle body assembly... No such luck. She's running better but not where it should be... Unknown on fuel consumption as of yet... More details to follow with that.

How do the plugs look?

sorry... I neglected to state the obvious fixes... I did replace spark plugs/wires swapped out coils to a known good coil... No luck.

They still look fine.

sorry... I neglected to state the obvious fixes... I did replace spark plugs/wires swapped out coils to a known good coil... No luck.

They still look fine.

Type of plugs?
Wire condition?
Fireing order correct? Should be 4-1-2-3 at the coil towers.

Remove the ignition control module and clean the back of it where it meets the tranny.

How is it running now? Did you drive the car around for a little?

Forgot to check the type of plugs... They are the more expensive NAPA choice. Wires are also new, NAPA. Yes the Firing order is correct, I did removed ignition control module, clean both mating surfaces, and are install.

Refilled tank yesterday, 25 MPG... Seems to be in the ball park now? What should I be getting? (Automatic Transmission)

It still has the miss, in gear, while it is stopped.

Ryan

*ONE more thing...

The collant system should be pressurizing, correct? I bought a replacement cap, as it sounded like the last one wasn't seating, the new one, same story I can hear air escaping when I squeeze the hoses.

I have a known good cap on my 96 that i will try today. No visable leaks throughout the system, and I dont seem to be loosing any collant.

Forgot to check the type of plugs... They are the more expensive NAPA choice.

This could be the issue. How old are they? The s-series are simple through and through. The fancy platinum and iridium plugs do not work right at all with these cars. Most times they lead to misses and eventualy non-running engines.

NGK copper plugs for a dollar or so each are the way to go. Get those fancy plugs out of your car.