SL2's RPM won't drop until stopped

Jack Bauer, Jr. · 01-12-2004, 02:01 PM

Kind of got a wierd problem. My 99 SL2 (manual) stays reved up until I come to a complete stop. Let's say I'm coming to a red light, and I've got it in neutral or I've got the clutch disengaged, the RPM will stay at about 2000 or so, until I'm TOTALLY standing still, then after a second, they drop to 900.

I tried searching, but couldn't find anything.

Any ideas?

Robert-sl2 · 01-13-2004, 12:28 PM

In the manual tranny cars the PCM keeps the engine up around 1200-15-- RPM when moving but the clutch is in or the car is in neutral (this is a safety feature so the RPM's dont jump as far if you let the clutch out fast w/o giving it a little gas first) then drops to idle when you stop. But yours sounds a little high.

monkeyracing · 01-13-2004, 10:07 PM

Yeah, my 94 SL1 has the same problem. I think it's probably the idle air control solenoid, but I'm not 100% sure, as I've replaced it with a clean junkyard piece already.

I think it's also possible it's one of the vacuum operated/actuated/affected sensors.

If you figure it out, let me know.

Jim

SILENTBOB SL2 · 01-19-2004, 12:34 PM

My 97 did the same thing. My problem ended up being the throttle body. Had an aftermarket one and it would stick from time to time. Just have to clean it out every once in a while

SNOWMAN · 01-19-2004, 01:28 PM

my 97 sl2m was doing the same thing when it first started getting cold...i asked my tech at saturn about it, he told me it's perfectly normal....that's the PCM's way of making up for the super cold air it's sensing coming into the intake.....you can check your PCV valve also...that might be needin' to be changed.....but seriously...don't sweat it, it may seem a bit high...but it's cool.....unless it does it ALL the time, then you should check into it....check to see if it's throwin' any codes ect.
-GOOD LUCK-

=DAN

wolfman · 01-20-2004, 03:42 AM

If it idles normally when the car is stationary, the posted behavior is indeed NORMAL.

mtgjudge · 04-05-2004, 01:36 AM

Okay, I just bought my 1995 SL1 (1.9 SOHC, 5 spd)and this is my first post to the forums.

I am having the same/similar problem.

Let's say I'm driving around at 3k RPM, and I shift up a gear. The RPM's will not fall below 3k until I disengage the clutch after shifting and engine load brings it down. The car routinely idles at 2k and then after several seconds, brings itself back to 800. Basically, the symptom is that it is *very* slow to return to proper idle speed. Sometimes, I'll have to tap the gas to rev it up above 2k and hope it comes to idle on the way back down. This happens most of the time, regardless of ambient temp.

I checked for codes, and I am getting the "boring" 12.

I took off the intake to the throttle body and sprayed cleaner in there. (My accelerator was sticking.) and lots of carbon flowed out. (Had the car up on a jack on the passenger side.) After working the the butterfly valve a bit my accelerator no longer sticks, but I still have the idle problem. I assumed it might be an IAC gummed with carbon also, or just misbehaving. I test the voltage with a multimeter and got 0.46 and 11.65 volts, repectively. (Last two contacts on the right, as per Haynes manual.) That seems out of the range (1.5 - 10.5v) according to the book, but maybe it's still within "street" tolerance? (Or maybe I don't know how to use a multimeter!

)

I haven't taken the valve off yet to clean it out, mainly because the torx drivers I had were either too long or too stubby, heheh. I did, however, send a bunch of cleaner down the port that leadsa to the IAC in the neck of the TB while the car was running. Idle...spray (cough, cough)...idle...rinse, repeat. That had no perceived effect after I put the air intake back on and drove it, so maybe I'm off on this one.

Whateya think?

Thanks in advance for the collective wisdom on these forums.

Wes
"Saturn Newb"

04-05-2004, 10:17 PM

its supposed to do that!

mtgjudge · 04-05-2004, 11:19 PM

Oh?

It's seems like a phenomenal waste of fuel and accelerated wear and tear on hard parts to me. Maybe I'm understating it, because if it's working as intended I have to ask....what is it supposed to accomplish? At the least, my clutch is gonna burn out from all the slipping at high revs.

**Ssicarman** · 04-06-2004, 02:20 AM

What you are describing is close to normal. When there is a speed signal into the PCM it will keep the rpm's up some for smoother shifting etc. If you feel it is to much then check the coolant temp sensor to see if it cracked/leaking and if the connector for it is corroded.