I dunno if this is normal for our cars or not..

I have stock twins Running rich man's non seq and a ported wastegate..

I have the boost line off the front compressor housing plumped right into the Wastegate...

and Defi BF gauges.. the boost being plumbed in at the meeting of the UIM/LIM where the nippple is originally plugged...

at partial throttles the needle is fine..

when u go WOT.. the needle "bounces" slightly i'd say it almost "waivers"

the variation isn't HUGE.. maybe 1-2 psi but its annoying and slightly unnerving.

currently the car is boosting 0.5 Bar.. sometimes creeping/bouncing it's way upto 0.6-0.7


thing it's a sign of a boost leak? wastegate isn't holding? BOV is leaking? or the lack of a boost controller to iron it out?

when I overhauled my engine i replaced all the Turbo gaskets, keg to LIM, LIUM to UIM gasket etc..




I'll be raising the boost soon to higher then stock levels (0.8-1.0 bar) area later on.. but just want to make sure this isn't a problem..

 

Do you have a restrictor pill in the hose or is it built in to the gauge nipple? If not, you will get pulsing because of the lack of damping.

 

I don't think so.. considering i'm only making wastegate pressure..

which is odd considering I re-used the same hose that was on the car..

would an AVC-R solve this problem?

 

Sorry - I meant the hose to the boost gauge. Some gauges have the pill built in to the nipple whereas some don't.

 

I had the same problem.

The first thing I did was melt the end of the plastic hose (for the boost gauge) with a lighter and then poke a needle through it. This was similar to adding a restrictor pill. It was still doing it, and at this point I realized the steering column plastic was shaking as I accelerated making the needle vibrate between boost levels. If i held the gauge while accelerating it was steady. Or if i only gave it partial throttle it was steady. So I added a rubber o-ring between the gauge mount and the column and I reinforced the plastic to keep it more steady. This completely fixed it.

You should also make sure all your gauge connections are tight and not leaking.

 

Both Kyle and I have experienced the same thing while out tuning customers cars with them doing the driving. The logs showed the problem with a fluctuating TPS voltage. The cause was driver shaking foot syndrome.

 

update..

I checked.. the wastegate does have the restrictor pill in it..

i've installed the AVC-R.. (man what a pain in the *** it is to get that wiring into the compartment from the engine bay!)

but I didn't have the correct Silicone hose size for the WG to solenoid..
so I'll finish the install and see if it still does it


I now have 3 map sensors in the car LOL..

Defi, AVCR, and stock..

we'll see if they "digitally waiver" as well

 

The restrictor pill we are referring to is not the one for the wastegate. Its the one in the line for the Boost gauge. some gauges don't have one.

Search bouncing boost gauge or something similar, you will find a 100 threads talking about it. I know cause I searched when mine did it. Unless you feel a weird surging its most likely something with the Boost gauge line, or what the gauge is mounted on. Chances are your boost is holding steady.

 

Do they sell "aftermarket" restrictor pills? My Greddy boost gauge came withe a restrictor but its still doing the bouncy dance. My datalogs confirms the boost is steady and it was fine before with the mechanicl autometer boost gauge.

thewird

 

I was using the vacuume line that came with the Gauge.. i'm suprised it doesn't have it's own pill..

never seen another turbo car does this before..