still couldn't solve the boost needle flicker.

[popdemonic]

My car setup.

-034's dedicated s/w for GT2871R Turbo
-GT2871R Turbo.
-Wagner EVO RS2 'EM.
-1.9Bar WG spring.
-044 Bosch FP/5Bar FPR.
-3Bar Vmap.
-440cc. Bosch big green injectors.
-Auto Box.
-Stock IC,DP,Exhaust with CATless.


It seems I'm chasing my tail here.I'm experiencing the boost needle

flicker when WOT.Firstly,I think it's the compressor surge.As the

GT2871R is one of the turbo which easy to get the surge from turbo.

after my well consideration,the boost needle also flicking even at

higher RPM(5K-6KRPM) without any rattle sound during the boost

needle flicking.So I'd write the compressor surge issue off from my case.

here's some parts I have done/replaced on the car during the test.

-Swap good known N75(K code).
-Swap good known 710N BPV/HKS SSQVII BOV(No fixed at all)
-unscrew the top of the WG to 0 Turn with 1.9Bar WG Spring.
-pressured test=OK.
-ignition system=Running the D585 coils system from EFIexpress.


I also post some video on youtube.
from 0.09-0.14secs.you will see the digital boost gauge is dialled back and forth
between 2.3 and 2.4 all the times(flicker quick on the analog boost gauge).

http://www.youtube.com/watch?v=Himzkx1qoO0

at 0.08secs the boost needle swing up and down.unfortunately,I have to let off the gas since the car in front of me hit the brake.

http://www.youtube.com/watch?v=QqmfpFQIskA

Can the worn WG,torn WG diaphragm cause these? I'm going to have the spared WG
on my car.

PS.skip the music on the clips.I forget to turn it off.

[20Vcqdriver]

Thought this was normal as the wastegate opens and shuts at WOT to maintain desired boost value. My analogue gauge flickers at I guess 10Hz between 1.2 and 1.3 bar at WOT in 4/5/6th gear...

[dest]

On a B5 S4 the gauge i had said you can stop it flickering by putting a small filter in the vacuum hose to the gauge. Just looks like one of those clear fuel filters but smaller

[Rusty]

My boost gauge flickers between about 3k and 4k rpm, you can hear the turbo flutterring and then it settles.

[GazzaG60]

mines rock steady. maybe a combination of turbo size and n75.mine used to fluctuate slightly with n75. rock steady with E-boost.

[HPmuirt]

Could it just be that the boost is only actually varying between 2.349 and 2.351 and therefore the display changes between 2.3 and 2.4 as it is rounding?

Cheers n

Si

[driftin jo]

Could it just be that the boost is only actually varying between 2.349 and 2.351 and therefore the display changes between 2.3 and 2.4 as it is rounding?

Cheers n

Si

I would say that's the nail on the head as this it a digital gauge with only .1 resolution .
Plum in an proper analogue gauge and see what it does.

[lind4hl]

or an gauge with glycerine inside, we have filled some gauges with glycerin @ work, and damn that helps,

had some gauges that fluttered between 40-75psi 4-5 times the second, so the gauge would break if we didnt fix it. filled it with glycerine and rock steady on 60psi..

Only fill gauges with glycerine that can handle it though! no boost gauges.. industrial type of gauges, but these work really good in cars and are very accurate. not som much "bling" though...

[popdemonic]

Ok Mates,I'm having the aftermarket boost gauge(electornical type),As the needle is bone steady if there's not s'thing wrong on the system.As my boost flutter issue.I noticed it fluttered like crazy especially when you 're on the hard driving condition.I need to stumble at WOT and sudden let off the gas and hit again.

Yesterday,my friend noticed the REV needle also hesitaing as the boost needle was fluttering betwen 1.5-1.7bar.

I know there must be s'thing wrong the the boost control system.Currently,I'm running the stock exhaust ,Downpipe.

it's darn restriction on the exhaust.I'm thinking the backpressure will push the WG valve to float and end up with

fluttering on the boost.Is this sound make any senses?