High idle

Hi. I've got a 99 SL1 with about 90k miles on it. Last week, when my wife was driving it about 50 MPH, the RPMs shot up to about 3000 and she had to pull over and wait after she turned it off. Last night it did the same to me, this time, it idled while parked about 3500 RPM. I have changed the coolant temp sensor, idle air valve, throttle position sensor, took apart and cleaned the throttle body. Still...the same. I turn the car over and the idle shoots up to 3500 RPM and if I try to drive it down the block, it won't change gears. The transmission place I took it to this morning said it wasn't the tranny. I took it to Saturn 2 weeks ago and they had told me I needed an ECT and connector. I did the ECT myself, but did not see the need for a new connector. Any ideas for the collective? Thanks a million in advance!!!

thats more that likely is a transmission/cluch issue sounds like the tranmission/cluch is slipping... if the rpm shot up and it did not accerlate.. however if the vehical pickedup a fair amount of speed...its engine related... i just cannot see the engine picking up speed without the throttle plate open to allow more air..

auto or manual trans? any SES light?

sometimes, the ECT will crack to the point it leaks coolent into the connector, successfully gunking it up. see if there is coolent in the connector, make the call for your self.

i'm thinking more of a vacuum leak. double check all hoses, bolts, and connections in the intake. did you replace the throttle body gasket?

auto or manual trans? any SES light?

sometimes, the ECT will crack to the point it leaks coolent into the connector, successfully gunking it up. see if there is coolent in the connector, make the call for your self.

i'm thinking more of a vacuum leak. double check all hoses, bolts, and connections in the intake. did you replace the throttle body gasket?


This might sound like a moronic question, but where might I find the vacuum hoses? I checked the only 1 I know of and it seemed fine. wish my Haynes manual had more pictures. I'll be looking at the ECT connector right now. I'm also replacing the EGR gasket. I took it off and cleaned it as best I could. I did not use a carb cleaner because I was told not to. As for the throttle body gasket, I did not replace it yet because I can only find it at the dealer and they are closed today. Thanks for the insight.

auto or manual trans? any SES light? also do you have the 2nd or 3rd gen?(the 99s was a transitional year. if your not sure, check the headlights, amber turn signal bulb = 2nd gen, amber lens on the turn signal = 3rd gen)

you can use carb cleaner on the EGR as long as its oxygen sensor safe, spray a little in the head to.

auto or manual trans? any SES light? also do you have the 2nd or 3rd gen?(the 99s was a transitional year. if your not sure, check the headlights, amber turn signal bulb = 2nd gen, amber lens on the turn signal = 3rd gen)

you can use carb cleaner on the EGR as long as its oxygen sensor safe, spray a little in the head to.


Wow, thanks for the quick response. It is an automatic. Yes, I have a SES on. The codes 0105, 0113, 0130, 0131, 0134. Mostly O2 sensor stuff. Could this be the problem. I had a mechanic tell me it was unrelated.

Oooops..amber light bulb.

Also, when I start it and I kick on the A/C the RPMs go down to about 2000. As soon as I tun the A/C off, it shoots right back up to 3000-3500 RPM. This sucks...haha

sometimes people who don't know how to drive a manual trans the right way will the cause the computer to set the idle high as to not destory the engine.

0105 - MAP/TP circuit error
0113 - IAT temp low
0130 - O2 sensor
0131 - O2 sensor low
0134 - O2 sensor no activity

interesting. i have a feeling the five codes are all one or two problems.

do you have a Voltmeter/multimeter?

problem 1 - although my wiring diagram doesn't show connections, i have a feeling all these sensors' wires run together. something may have cut them all at the same place. check for reference voltage at the MAP and IAT sensors.

problem 2 - i dont know what causes the code 0105, but i wonder if code 113 causes it, since the IAT and MAP work together to determen the air/fuel mixture. ether way, check the IAT. also since the computer doesn't know the right air/fuel, it doesn't know what to do with the O2 sensor readings.

problem 3- same as 2, but the O2 is just bad in its own right.

out of these three ideas, i'm betting number two.

I do have a multimeter. However, I'm not too sure where to connect either end when doing these kind of checks. Thanks again so much for your help. I"m looking in my Haynes manual to see how to do it.

lets focus on the IAT sensor. with your voltmeter, hook the black wire to the car's ground. in the IAT connector ( the IAT will be disconnected for these tests)there will be two leads, hook up the red wire to each of the leads, one of then should have 5 volts with the key on. if you don't have 5 volts, trace the wires and look for any brakes in the wire. if you do have 5 volts test the IAT sensor.

in my hanyes, on page 6-1 there is a chart for the resistence of the sensor at certain temps. use the ohmmeter function to test this. i might just change the IAT anyway,its the same part as the ECT. but not as messy to change.

Well, the connection tested fine at 5 volts. I then tested the sensor itself. This is where I'm unsure. If I read it right, the sensor tested at about 3k at about 80F. I am going to put the sensor in the fridge for a bit, then measure again, then under a hair drier and measure again.

at 80 it should be 2.4K to 2.7K. 3K should mean closer to 70 or 75. so not that far off. like i said for $15 i would replace it anyway.

i don't know why, but my mind keeps going back to the EGR. which leads me to think of problem 4(although i have never heard of anything like this, it should throw different codes) the EGR is stuck open letting to much hot air into the intake - clean it and let me know what happens

but the codes are leading me to thing a sensor, if you were able to get your hand on a nice OBD2 scanner, you can get the sensor readings in real time.(hopefully we will find the problem before that)

another idea i have heard of but never done myself is using the carb cleaner to find a vacuum leak,just spray it around all the places where there could be a leak (gaskets, hoses, connections, ect..) when it bogs down, there is your leak.

Hi. I got frutrated and took it in to a shop I usually go to for brakes and such. It turned out to be a power brake check valve...yes, that one. $4 part connected to the booster....Thanks much for your help!!!!

power brake valve? i've never heard anyone have a problem with it before. i'll have to remember that one. thanks for the info.