I'm cleaning up and painting my intake manifold. In the process of doing this I saw this mechanism in the throttle linkage that I did not know what it did. By measuring it and sticking it in the freezer and remeasuring I determined that it was to open the throttle a bit in cold temps. (I had a hunch) My question is wheather or not it is necessary with megasquirt. Wouldn't the IAC be used to increase idle speed durring cold weather warm up.
I am a de-cluttering fan and if I can remove something that is not necessary I will. But this is Michigan and if the car dies all the time on the cold mornings without this little thing I will be sad.

 

That's the thermowax. If you're planning on using the BAC valve to control the idle speed, the thermowax isn't necessary. That's what tofuball is doing on his car.

 

If you plan to drive through the Michigan winter, you may want to consider leaving that thermowax device intact. There's a couple reasons to do this: 1.) The coolant line feeding the thermowax passes through a fixture on the BAC valve to keep it warm, preventing icing on cooler days. If you leave the coolant line in place, it'd be pointless to remove the thermowax device, 2.) The BAC valve on its own may not have enough control authority to hold your desired fast-idle speed at very low temps.

I installed MS in my daily driver S4 back in the fall of 2002. The thermowax device was my only fast idle control for two cold years and on its own it worked great. Those two years included two cold Canadian winters, and startup/warmup once tuned worked just fine.

 

The BAC definitely has the ability to idle up the car in very cold weather... for example, we have it only partially open on warm-up, and even on days when it's like 30 degrees it idles up to 2000. It gets colder here so we'll have to see if that stays true or not.

however, if the thermowax is still working, I'd leave it in.

 

This is not going to be a winter car. I have no heater (never did, it's a beetle), I have a stiff rear swaybar, and I just bought 17s and they will be getting some sticky tires. That being said it can still get really cold in the morning on what would be a descent warm spring or fall day. I like minimalism but not at the cost of function. I'm just gonna leave it in.

 

yeah, if it's not broke, don't fix it.

I'm actually not even sure why tofuball got rid of his thermowax....

 

Cuz I hate those coolant lines (I've had them blow up on me TWICE), and it makes it SOOOOO much easier to remove the intake manifold. I'd rather use the BAC to control idle, electric solutions please me.

However, I personally reccomend everyone leave the thermowax in unless you want the BAC to control fast idle.