Andrew LB

My IX is bone stock engine and drive train wise except for a drop in K&N. I just installed my VDO boost gauge and noticed that the boost is not very consistant. Sometimes it will hit 20psi and hold anywhere between 15 and 19psi. And sometimes it will only spike at 17psi and hold around 15. I don't see much consistancy in my boost peaks and hold points like i have in previous turbocharged vehicles i've owned.

I assume this boost fluctuation is normal with a stock car and tune right? The thing that really stuck out was the car holding solid at 19psi up to 6k today... but during the same 2 mile drive, only held 15psi in the same gear (third).

Warrtalon

iTrader: (6)

No, boost fluctuation is not normal. Is it changing when doing the same low rpm roll-on to boost, or are you talking about it being different when you start from low RPM vs when you rap through the gears quickly without ever dropping down to peak boost RPMs?

Btw, I highly doubt it holds 19psi at 6k in any gear except maybe 5th...maybe.

thetox

iTrader: (4)

only thing I can think of is boost taper that occurs when the rpm's start to climb that high. ive had my car peak at 21 but it always falls back down

Andrew LB

Thats what concerned me. It stuck right at 19psi today in third gear and stayed there until i let off around 6k. Either something is wrong or the gauge itself was damaged in the crash when my Audi got totaled by a drunk driver.

The boost always spikes and then tapers off, like it should. But it sometimes spikes higher than other times, and sometimes it tapers more than other times.

It just doesn't have a consistant, predictable spike and consistant amout of taper each time.

i'll go check my vaccuum lines and go run the car again to check some things.

Mine does the same, but sometimes it drops 2psi, sometimes 4-5psi.