Just installed my Manual IAC Enable Switch.
 

Many thanks to Cfg, Skewbe, and perhaps others who engaged in conversation with me on SaturnFans a couple of months ago regarding the IAC solenoid/motor.

I now have a nice rocker DPST switch mounted in the center console between my shifter and cigarette lighter. Four wires were threaded through the grommet and I spliced the Green/Black wire and the Blue/Black wire on the IAC connector. Solder and zip-ties abound.

Well, it takes some getting used to...I will have to optimize the best time on "my route" to work to disable the IAC. As others have stated before, I will need to wait until the engine is relatively warm and I am at a dead stop.

Unfortunately I cannot do what would be perfect: popping out of gear at 55 MPH to coast down to a stop sign with the idle as low as possible. Reason: When the car is moving, the computer thinks the idle should be 1100 RPM. So if I disable the IAC when moving, the lowest it will get is 1100, and I am not gaining any FE.

HOWEVER, the switch is more of a long-term decision deal. I.e. before starting the car I can decide whether I feel like RPM matching when shifting / rough cold starts or not. Regardless, I can switch it off when the car is warm and I am sitting at a stop.

Anyone have any bright ideas about how I can optimize using my new toy? FWIW I ordered it from McMaster-Carr...PM me for the P/N if you're interested.

I tried unplugging mine and it zoomed up to 2400 rpm and held there with IAC unplugged.

IMO, if I was programming it, I'd want it to drop to XXX rpm as soon as I was off the gas. The 1100 rpm idle and long delay for it to get down to 750 is aggravating with gas costing as much as it does anymore.

we're not even talking about peanuts here though. idle speed is so inconsequential i'm surprised anyone has brought it up, or actually done something with it.

I think the point is when you combine a few inconsequential things it adds up to a considerable improvement. Wheel skirts for one, they don't help me much. I spend 80% of my time below 40mph.

The nice thing about lowering your idle to say 500rpms is when you EOC its much easier on the motor mounts. There is less stored energy. An engine off above 900 rpms results in a lurching stop from the engine compartment for me. Sure I have an engine mount thats on its last leg but. When I key from low rpms, it quietly settles with out a fuss.

Also consider that idling at 500 rpm will consume more than half as much fuel as with 1100rpm. My 70mpg segment had absolutely no idling only EOC. But there are many situations where low idling would be better than a full blown EOC. On hilly highways for instance.

It does not sound like you own a scangauge yet :) . When you can see the fuel flow rate it motivates some to try to reduce it. This partly comes from the situation where a Saturn will take the idle rpm to max after an EOC and restart. It will not reset until the vehicle speed drops to zero. We were dealing with idle speeds above 2,000 rpm.

Part of the reason I installed it is so that I can make my coasting more fuel efficient. I am not comfortable with EOC because it's too much of a hassle and I don't like the lurching when bump-starting. And yes, my route to work has lots of gently rolling hills and a few stop signs. There is JUST enough traffic to make P&G impractical.

Jim Dunlop -

This is great. I love mods that you can turn on and off as you please. I have a long period of driving on the city streets before I hit the freeway, at least on the "go to work" leg of my trip. With the mod you describe, I would be able to take advantage of my low idle RPM during that leg.

If you can post a few pix, that would be cool.

CarloSW2

I was thinking of taking pics, but there's not much to see. It's a DPST rocker switch mounted in the center console with four wires going to the spliced blue/black & green/black IAC wires. The splicing is all covered up by electrical tape and flexible corrugated plastic conduit.

Would you like to see the switch mounting?

Jim -

Yes please, but at your convenience is fine.

CarloSW2

So when you flip this switch off the idle air control valve stops where it is at? So if you are sitting at 1100rpm idle and turn it off that is where it will be when out of gear? I am trying to diagnose my idle that tends to speed up when going out of a gear. I tried unplugging the IAC connector while the engine was off and then start the car but that ended up in a constant high-idle.

BTW, does this throw any error codes? I seem to remember having a code from unplugging mine. Maybe I should have unplugged it with the car on?