Heyo,

My 93 SW2 has been a sports car compared to my work truck. But since three days of rain and a stall out in the road. It has had a high idle in park and neutral 2000-2400rpm and when I shift to D or R in surges. It barely stays awake. Sometimes stalling, but barely. Everything was running great on her until we had three days of rain and I went to work and she stalled out a couple blocks from my place. Me and a friend man-towed her back and since changed the coolant temp sensor, fuel pump relay(def wasn't the problem), isoheet(fuel dryer) in the tank. I did spray the wires with a mist and no arcing. Now i'm lost and my mechanic enjoys it when I visit and have to get AAA'd back to my house a mile away. I guess he's making $ on me somehow. I will do all of my own work since if i pay labor rates the car might get totalled. Any ideas on the idle???
Justin

 

im thinking vacuum leak. that or something got wet - but it should have dried by now

oh, did you buy your ECTS (coolant sensor) at an authorized saturn service center (normally a large GM dealership) and did you get the connector for it? They should be replaced as a pair, and there are problems with aftermarket sensors

I remember those 3 days of hard rain, went puddle hunting in my brothers truck, luckily my saturn is down or I wouldve drowned it probably

 

So a vacuum leak.. I look at another forum with same symptom and someone else found it be a leak in the intake manifold gasket. I guess that wouldn't dry out. But then I just sprayed the manifold with carb cleaner and no change in throttle.

I replaced the cooland sensor with a NAPA part. Just the sensor with a clip on its butt. And actually the car was slipping pretty badly. I didnt bring that up but the sensor made the slip go away.

I'm looking into vacuum leaks more, and thanks for your input

 

I am having a hard time equating rain to your problem other than coinsidense. If you were having a problem in the rain I would point fa fionger on electrical, but it would have stopped being a problem I would think when it dries out.
However there have been a number of people complaining about carbon build up on the throttle body and something like that would cause either a sensing problem or a mixture control problem and while I agree with your comment on performance (mines a 94) the age of them can point towards something like that which can creap in.

 

I find it funny, and ive mentioned it a few times that I got the shop set, I was reading through it today and it says in the shop set
"Residue accumulation can cause stall after start with a warm engine, stall during acceleration, or a sticky throttle on the vehicles engine"

The three days of rain may have moisened the residue up, making it easier for another layer to accumulate. When i took my throttle body off, it was pretty nasty

 

Thanks guys for your ideas. That does make sense with the throttle body carbon build up after the rain. I've been bouncing ideas off my local mechanic and he said once i had it off (to change the gasket) go for a pipe cleaner in those """whatever they are called"". I'm gonna pull it with in the next couple days and keep it posted.

Thanks

 

I forgot to mention I did get a sputter when I tried spraying carb cleaner at the intake manifold gasket from underneathe. The first time I wasn't reallying hitting the gasket But thats what gave me the thought to keep figuing on the intake side.

 

Ok so to clarify what. I said earlier. I had taken the throttle body off not the intake manifold. I cleaned the throttle body and the surging idle is gone! It was nasty and I saw the small holes that I cleaned too. But whats funny is that the high idle in park and neutral are still there. Caused by in unrelated problem? Hopefully not the trans. I don't see it would be the intake manifold gasket vacuum leak because it only does it in park/neutral settings.

 

I'm back and now more frustrated. So the car has been garaged for the last month. Moisture can not be an issue. I start it up. Sometimes idle in park and neutral are normal. A quick spin around neighborhood and I am getting some slippage, high rpms but no acceleration. I pull back into driveway put in park or neutral and it ramps up to 3000rpms. Back in drive and now it's surging again. From almost stalling up to 1500 rpms. Errrr!

So here's what I did. From another post I saw that idle air control valve/motor may be bad or getting bad control voltage, from service manual. So I pull it, a little carboned up so I clean it off with the mass airflow sensor cleaner. Back in. Put back together. No result

Then what the service manual said. Check green white and green black wire terminals for voltage. It said it would fluctuate between 1.5 and 10.5 volts. Key on, motor not running, I got 11.07 volts and then when I weighted the pedal it dropped to 10.8 volts. Outside the range.

So did I do this test properly? Since the voltage was higher then recommended I assume we are not talking about a ground or loose wire. Does this indicate a problem with the PCM and how bad is that for my wallet. No mention on how to check it in my manual.

I haven't heard from you guys in a bit. I hope your still out there. I,d really like to get this "golden eagle" back on the road

 

Quote
So did I do this test properly? Since the voltage was higher then recommended I assume we are not talking about a ground or loose wire. Does this indicate a problem with the PCM and how bad is that for my wallet. No mention on how to check it in my manual.
Unquote

O.k., first off as far as I can go, maybe some one else has a better answer and from personal experience I can only hypothesize.

My book says you need a scan tool to do this test. Now whether it is absolutely needed I do not know for sure because as to what I should be getting I did not pursue things much further as I would think that by pressing the gas pedal or moving the throttle body butterfly I think you would get a change in the reading if you are using some form of a digital volt meter to obtain the reading.
Now a couple of things need to be mentioned to make sure we are on the same page.
Why?
I am **** that way and I have spent years helping people trouble shoot things that were supposed to know what they were talking about and generally did not.
What does weight the pedal mean. If I am supposed to know I don't.
If I have to guess then we are not on the same page.
I think you mean depress the gas pedal to increase engine speed.

Secondly just to make the comment because this is not the first rodeo I have ever attended.
You made the statement you think this is problem with the PCM, the least understood and most expensive part of the equation.
A not uncommon and most extremely expensive mistake made often while trouble shooting. If you really are mystified by a component, then change it simply because I guess.
Sorry not pointing specifically at something other than it is an expensive common error made by many people.
Who should in the field I was in, have known better.

Now I did not look further into my documentation to see what it was you were doing other than to find a wiring diagram and schematic. And the Green White an Green Black appear to be an A/C signal that is sent from the IAC an acronym for the Idle Air Control Motor so I will use it. Sent from the IAC to the PCM or ECM depending on what document you are looking at, the computer that runs the motor. It should very I would think with a change in engine speed. One of them anyway and maybe both. The other two wires, blue white and blue black are probably a constant value.
It is probably a high frequency AC signal that can be read with the DC setting of your digital volt meter.
As long as the Blue/White and Black wires have some constant value on them, the Green/white and green black wires should change to something. IF the IAC motor is working correctly.
The odds are and the operative word is ODDS that the computer (ECM or what ever is not the problem)
What seems to be needed is a new IAC Motor
Based on your reading results you posted.
As long as those results indicate a bad unit then it is not going to hurt to try to clean it. You already said you did, how? Not sure it is good enough and don't care clean it again. Only this time soak it in gasoline.
Why gasoline, it is cheap cleaning fluid.
It probably will not damage anything electrical. You said it was full of carbon and yuck. There is a moving part in there some where some how that measures air flow through the unit as controlled by the butter fly on the the throttle body. As you open the throttle there is less air flow and it should show that to the computer. If the moving part does not move, then the signal can not change. At least as it should.
Don't know what it looks like and I am not there to see it and tell you. The way it would work is that when at idle, the air flow would be at some form of a maximum level and when the throttle is open, the air flow through the IAC motor would decrease.
So this thing is >probably< telling the computer how much air flow is getting to the engine and the computer is deciding how much gasoline to give the engine to control idle speed.
There are other things looked at too, but if the throttle body position switch says the throttle is closed, then the engine must be at idle (with or with out load, load being the transmission engaged if automatic) and idle rpm must be maintained if engine warm at what? 650 rpm? That is a software preset. non adjustable. The computor needs to know what is going on and the IAC seems to be sending a wrong signal. So soak it in gasoline and see if you can get it cleaner and it will work maybe if not you will have to try and find one and with the car out of production no matter what is said. GM is or will or already has stopped making some parts and the list is growing as we read the forums.
Good luck