Thread: Intake plenum vacuum to air intake pipe Q?

This will be year 4 season of no cold motor idle diagnosis, I really hope this is the year. My motor will not idle till its warmed up, even now after a winter slumber and new battery she now struggles to idle warm.

The only time she has idled properly was back when I learned there needed to be a vacuum signal from the back of the intake manifold to the air intake. I had a nipple welded on after the MAF, uncapped the nipple on the intake plenum, and connected a hose. She idled for about a week and then slowly dropped off.

I'm trying to theorize and wonder did I make a mistake and need to have the vacuum before the MAF???

I've cleaned and replaced the iacv. I rigged the AAC open to mimic a warm motor and replaced that as well, also tried just a hose. I've made many many adjustments to the tune in realtime. I've swapped out the coolant temp sensor. There are some areas of the tune that I didn't touch that may help but I think it's more mechanical opposed to tune. although the AFR's seem to be backwards between a cold Motor and a warmed motor. But now I'm having AFR issues since winter ended which has me baffled as well.

It'd just be nice to idle and warm my motor while I'm in the house putting my shoes on.

Sorry, went on a rant...so that vacuum? Before or after the MAF?

the nipple should be before the maf just like on a stock de.

Before the MAF. So between the air filter and MAF opposed to between the MAF and turbo? But then wouldn't it basically be like a boost leak?

I don't think we're talking about vacuum lines here... Are we?

good example

just two examples i found

Both those pics are blow through, I'm draw through. I already tried though and epic fail as I thought. It's basically unmetered air. Oddly it idles much better with the line disconnected creating a vac leak.

Ben, you're a guy that knows things...what should iacv % be? I was monitoring in realtime and watched the iacv go from 95% to 10% which also affected the idle. The motor was warmed at this point but now she's struggling to idle warm. Will the iacv also affect AFR's? Can the iacv be affected after the car sat for 5 months?

doesnt matter blow through draw through same thing should be done in regards to that hose. first one isnt blow through

I wonder what your temp idle in the tune is set at. since you have a realtime I would look into those parameters and try and play around with those.