MSefi.com read only forum (Jan.15,2018)

Hi Megasquirter’s,

I want to control cold start-up / fasts idle using an IAC.

Because I have 4 ITB setup, I built a common vacuum rail, similar to the one shown in the following link. http://77e21.info/msidleair.htm
The difference in my case is that I want to use an IAC valve rather than a PMW one
I have a 4 wire IAC and an enclosure, both from a Peugeot 306. (see attached pictures)

The IAC is similar to others I’ve seen and I wouldn’t be surprised if its interchangeable with many of them.

Today I wound out the IAC piston so that when I screwed the IAC into its enclosure. I expected it to be in the closed position and hence, no air to pass through it.
To test it, I tried blowing into the inlet, but some air seemed to leak through.

I would have thought the piston would be rubber or something that ensures an airtight seal but it seems to be metal (?)

Aren’t they supposed to be 100% airtight when closed?

Sam

They are not absolutely air tight. But the air that gets through is almost always the same. Just like leakage around the throttle shaft. If it opens to a wide open position and closes to a very little bit of air, it is/should be OK.
Holl

Hi,

This subject/thread seem to fit perfectly to my question.

I'm installing megasquirt to 350CID V8 TBI. So far everything has been going rather smoothly.

The question is about IAC. I can move it from test mode. Run-position - test drives it out ie. closes the airgap as expected and home position test drives it inwards. Still, in idle-control - setup the homing direction is 'closed'. Which I think is wrong. I tried to change it to 'open', but then to me the IAC movement didn't make sense or I just didn't know how to test it properly.

In megamanual it says that if IAC is wired backwards you can turn it just by switching the pairs, but I didn't see any definitions on what is right and wrong directions.

Just got your question.
Later tonight I can look at some records but for right now here's how to test it easily.
I'm assuming you have, oh jees, I don't remember what the name is, but it's the initial IAC start used when you stop to get gas. It's a high idle for 3 or 4 seconds, then idles back to normal.... If you have this warm starting, high idle set up, it's easy to test.

So, Warm up the engine to normal operation temperature.
Turn it off.
Then turn the key to "ON" not start just "ON". for 3 seconds or so. This initiates the start high idle position on the IAC. Turn it off.
Do this again, one or two times. This should open the IAC to a much higher than normal initial idle position.

OK, start the engine. It should idle much higher for 3 or 4 seconds (depending on you settings) then idle down, back to normal.
If it does this, you have it setup fine. Yeah, their wording could have been a little more clear. But then I'm a technical writer for a large company.

Hope this helps. Enter your MSQ and version stuff. (Look just below my name as an example.) Then post again.
Holl