NA IAC plumbing (or lack thereof)
 

Using a map sensor, is it necessary to plumb in the IAC valve into the charge piping on a 1.8 NA or can you just throw a breather filter on it? In the past I've always had it plumbed in, but with my current car it's open. Will it create a boost leak or does it seal once the car is off idle?

I have always been told that it will produce a small leak because it does not seal completely. I have never actually tested this though to see for sure.

I ran mine open with a breather filter (naturally aspirated), and it sounded like shit and the idle didn't work as well as it used to. Car ran fine otherwise. When going FI, I re-plumbed it back into the intake because I thought it might leak backwards in boost.

So maybe?

were you running an aftermarket ecu using MAP based speed density?

there's no reason it can't be open to air, if it leaks in boost (which it shouldn't), install a check valve.

Thanks for the help guys. Never even thought about a check valve, that seems like the simplest option. I really wish there was an idiot proof way to get an NB throttle body to work, but I couldn't ever get the TPS working right.

yes- MSPNP2 (forgive me father).


A check valve would work... I just cut the old stock rubber tube and made a bung in my intake piping to attach.