Actuator Or Boost Controller Stuffed?

[Mr_G]

Hey guys,

Its been bugging me for a while and managed to record the boost stutter on my gauge today (Defi). Anyhow, basically what happens is when you give it abit of a boot from off boost to on boost, if you do it gradually or in a higher gear, it stutters...

It was evidant through the playback of the gauges, that the boost needle was vibrating at certain points and slowly reaching full boost. It didnt stutter all the way, just sometimes...

Its kinda weird and bugging me, that maybe its just the bleed valve im running that came with the car, or possibly the actuator could be stuffed? Most noticeable it happens when going up hills and putting the gas on...

Any ideas would be appreciated.

Car type: s15

Mods: STD Jap spec BB turbo, FMIC, Pod, full exhaust, bleed valve boost controller, GFB Stealth fx BOV (set to plumback)

[Al]

It is called "compressor surge", sounds like an atmo BOV but when you are on the power and does not happen on FULL throttle.

Unfortunately there are are few things that can cause this.

1/ The type of boost controller

2/ The turbo actuator

3/ ECU tunning

4/ The turbo.

First two are obvious; try an electronic boost controller (EBC) and fit a new turbo actuator. Unless you have a friend that lets you borrow parts off his car you may buy both items and still have the problem .

ECU Tunning: Some people have managed to remove or reduce the surge with more tunning. Not sure what needs to be done, but i have read that the tune can remove some/all of the surging problems.

The turbo: This usually happens with a "hi-flow" turbo. The turbine wheels used are mis-matched or slightly too big for the housing. This makes the turbo compress too much air for the engine, thus bounces back into the turbine.

Also test you BOV. Remove it and block the hole (temporarily). Go for a drive and see if the "surge" occurs.

I am not a mechanic, just what i have learnt through my experience, forums and chatting to various people. I had the same problem; this surge and the excessive lag (550hp hi-flow) made me buy a genuine HKS turbo, problem solved......... .

Good luck.

[paulr33]

my stock turbo does you can hear it chop as it comes on boost

no harm done that i can see of. i dont see pressure bouncing however when mine does it

[Mr_G]

Thanks for the replies guys, ill swap back to the std BOV and try a different boost controller when I get the chance too

Car still has the std ecu, but will be getting the PFC treatment later on I dont know if its full compressor surge, cause I know what that feels like

Its just when its boosting, that if you only give it partial stick where it makes boost gradually in comparrison to full stick, which opens it right up, then it usually has this problem.

I also tend to get abit of boost spike which aint cool I think im going to purchase an EBC, i used to have the std valve set up with a turbosmart boost t and never had any dramas what so ever in terms of spike and surge...

[BezerkR32]

Sounds like a missfire under load

Thanks for the replies guys, ill swap back to the std BOV and try a different boost controller when I get the chance too

Car still has the std ecu, but will be getting the PFC treatment later on I dont know if its full compressor surge, cause I know what that feels like

Its just when its boosting, that if you only give it partial stick where it makes boost gradually in comparrison to full stick, which opens it right up, then it usually has this problem.

I also tend to get abit of boost spike which aint cool I think im going to purchase an EBC, i used to have the std valve set up with a turbosmart boost t and never had any dramas what so ever in terms of spike and surge...

[paulr33]

mine is a really quiet fan chopping/slicing sound

its not a backfire, pop, fart or bang or anything

r31nismoid has heard it on my car before

[Al]

Thanks for the replies guys, ill swap back to the std BOV and try a different boost controller when I get the chance too

Car still has the std ecu, but will be getting the PFC treatment later on I dont know if its full compressor surge, cause I know what that feels like

Its just when its boosting, that if you only give it partial stick where it makes boost gradually in comparrison to full stick, which opens it right up, then it usually has this problem.

I also tend to get abit of boost spike which aint cool I think im going to purchase an EBC, i used to have the std valve set up with a turbosmart boost t and never had any dramas what so ever in terms of spike and surge...

What i highlighted in red is compressor surge. Only occurs on partial throttle and acts fine on full throttle.

Sounds like a missfire under load

I think a misfire would also occur, if not get worse, under full throttle.

[Primordial]

Mine is doing this too... If I'm on WOT, generally it doesnt do it (only sometimes)...

Part throttle though, it will surge about twice a second while boosting, and give a noticible surging effect to the acceleration! Its very weird! It's almost as if an actuator isnt able to hold the pressure and is creeping open (or closed) when high boost is reached then it drops and then builds up again and so on...

???

[Mr_G]

Cool thanks for the input Al.

Ill be trying a few things soon. Going to buy an EBC since I want one anyhow for gadget factor and to protect the car from overboosting. Also ill be getting a bigger fuel pump which is needed anyway, cause Im going to up the power shortly by using a PFC.

I checked the valve today, its on partial atmo, like slight atmo, but mostly plumback. I do get a fair few shares of backfires tho.

Is there anyway to vent more pressure to reduce this surge on the compressor wheel?

P.S i dont feel like buying a hks turbo