VW GTi and Idle air question

majic · Post by **majic** » Tue Nov 08, 2005 6:23 pm

Does anyone know if you have to use the IAC option with the newer volkswagens? I know that there is something called "secondary air injection", but people sometimes take that out. And the idle air controller... help me understand how it works. It supplies extra air at idle to produce a stable idle? Why is that such a necessary thing, and why can't cars be tuned to idle properly without it?

GeorgeGt · Post by **GeorgeGt** » Wed Nov 09, 2005 4:01 am

if u dont have air con , then u dont need idle control. Mabye fast idle for warmups , but thats all.

bleoh · Post by **bleoh** » Wed Nov 09, 2005 6:10 am

A cold engine needs different fuel/air mix andidle speed to have a good strong idle. The IAC is part of that.

majic · Post by **majic** » Wed Nov 09, 2005 8:07 am

Yeah.. I did some reading in my bently last night, and it turns out that the secondary air injection is only for warmup (injects air into the exhaust to make it burn off the rich mixture, heating up the 02 sensors quicker). Since they are down-wind from the headers (the 02 sensors), they are heated, anyway... so not much use in the AIR (that's the name they use for secondary air injection) system. Even still... the PWM design for the IAC will operate the solenoid that it uses for the control valve?