MFslacker22

Does your boost gauge flutter at idle? Mine does and my BOV isnt leaking. What could cause it???????

thanks

tubingchamp

iTrader: (3)

Did you tune your car?

NgoRX8

iTrader: (1)

you could also have a vacuum leak after the TB.

MFslacker22

how would this affect a fluttering boost gauge?

mysql101

Important question: Where is your boost gauge getting the vacuum source? Best spot is just before the throttle body. Worse is on the side of the engine.

NgoRX8

iTrader: (1)

I believe you mean after the throttle body from the vfad nipple. you would not get a vacuum reading before the throttle body.

mysql101

Actually I mean plum your boost gauge to the top of the intake manifold.

MFslacker22

its on top of the TB. I plugged the vfad nipple.

Easy_E1

iTrader: (2)

And what are you using "On top of the throttle body"?

MFslacker22

thats hose that kind of looks like a handle, I cut it in half and stuck a T fitting in there.

Easy_E1

iTrader: (2)

Dude that's the fuel system purge solenoid vacuum port.

Easy_E1

iTrader: (2)

Repair that hose you cut and plug into the VFAD nipple. And you wonder why it flutters.

KrumbZ

iTrader: (3)

face palm!

MFslacker22

ive seen a bunch of cars on this forum with that setup. Why is this bad again?

Easy_E1

iTrader: (2)

I've never seen one. But let me explain.
First off its a PURGE solenoid from the fuel tank evaporation system. Your fuel tank is under a small constant amount of pressure to keep vapors at a minimum. The release of fuel vapors is accomplished by a canister purge solenoid, which is placed in series between the canister and the engine’s intake manifold. This solenoid controls the quantity and rate of vapors being released by cycling on and off in what is called a duty cycle. A duty cycle is the solenoid’s “on time”(open) compared to its “off time” (closed) as a percent of the cycle. The vehicle’s Powertrain Control Module (PCM) determines the duty cycle of the purge solenoid. When this system is purging the fuel tank your boost gauge will flutter due to a loss of vacuum. And a small increase in pressure due to the differential between the Fuel tank pressure and the Intake vacuum.
Thus flutter of your boost gauge.

MFslacker22

well i figured out why it was fluttering. One of the hoses was split. It doesnt flutter any more. So, there was a vacuum leak, how will this affect the tune of my car? Will a vacuum leak will make the car run richer or leaner?

EDIT: I also changed it to get the reading from the vfad nipple. Will this mess up the tune anyway because it was hooked up to the fuel solenoid?

thanks

KrumbZ

iTrader: (3)

i found a picture of the setup u r talking about

Brettus

iTrader: (2)

Mine has the boost guage hooked up there - never had an issue with it .

As far as your tune goes - it would only screw it up if the leak was large and the car was actually tuned with that leak present .
If not - it would only mess with the fuel trims which will self correct once the hole is plugged .

MFslacker22

ahh yes thank you!!