boost strange readings

[crazymat666]

i noticed today im boosting 7-8 psi standard boost but past 6000rpm it raises to 9-10psi

why is this? is it because of the vvti?

talkin bout vvti when does that kick in at wot rpm jst wondered as i had a integra type r dc2 b4.

 

[LuPix_S15]

I think VVTI is much earlier mate... probs nearer 5,000 ish

But I'm sure this won't have anything to do with boosting of the car... the stock turbo should come onto full boost early (around 4k or less) which is why it's such a great car to drive so not sure why yours is boosting even more at the top end?! If anything was leaking you'd be dropping boost when you push her hard :wack:

 

[DeanS15]

sounds like boost creep but i didnt think that was common to the standard turbo.....vvt on these cars isnt noticeable at all, not like the vtec or mivec system......

 

[crazymat666]

boost creep?whats that?

yee i knew vvt wastn the same power as vtec but just wondered when it engages really
obvs like you say its not leaking boost or pressure wud drop so im happy its higher as it pulls like a train but just wondered why really haha

 

[DeanS15]

this is good reading mate, http://flatironsrally.typepad.com/faq/2007/12/what-is-boost-c.html

if i remember when i had just bolt ons such as exhaust and filter - boost went up to 0.9 bar but pretty solid.....

 

[JEZ 8553]

Boost creep is normal on a S15 when you change exhaust, decat etc due to the higher flow and loss of back pressure. Id get an EBC to sort this out.

 

[crazymat666]

EBC?

 

[crazymat666]

this is good reading mate, http://flatironsrally.typepad.com/faq/2007/12/what-is-boost-c.html

if i remember when i had just bolt ons such as exhaust and filter - boost went up to 0.9 bar but pretty solid.....

nice dean cheers

so if i failed to resolve this would it cause any problems??

 

[LuPix_S15]

Basically boost creep is when the wastegate in the stock turbo cannot handle anymore flow upon opening (so at pre-defined boost level the wastegate opens which holds boost at a certain level). And since not enough exhaust gases are exiting the wastegate quick enough, the pressure continues to build within the turbo which means you end up running 'more' boost. Well, that's what I worked out boost creep is so if I'm wrong somebody correct me!! :wack:

EBC = Electronic Boost Controller i.e. devices such as GReddy Profec B, Gizzmo MS-IBC, HKS EVC, Blitz SBC which are all electronic units that read pressure the turbo is producing and AFAIK, all use solenoid technology to measure this pressure and operates the wastegate actuator to control boost at preset levels etc.

 

[Dan H]

I've just been out in mine tonight for the first time since fitting my sports cat, twin downpipe, and GReddy elbow, and noticed the standard boost guage pushing around to 0.9 bar! When I got home I checked the peak reading on the turbo timer, and it was 0.93! Before, the peak was around 0.7. Now it pulls much better at the higher end of the rev range now, previously it felt a bit strangled.

The only other things done to it are a Fujitsubo Legalis R cat back, and a HKS panel filter.

 

[crazymat666]

yee mine has
FMI
blitz filter
exhuast system
and it pulls 7psi untill 6000rpm then 9psi lol

very strange indeed maybe a map will sort it out.
im gettin a new walbro fuel pump fitted soon and the idle control vavle cleaned up as i have a funny idle wen warmed up.see if that helps atall

 

[LuPix_S15]

Make sure you guys get a fuel pump sorted before you push beyond 0.7 stock boost. This one is very essential esp when you've de/sports catted which gives the turbo new breath of life

 

[DeanS15]

^^^ agreed, this is widely known as THE essential first mod due to originals being rather crap.....

 

[crazymat666]

i have a walbro sat waiting to be fitted this friday

 

[LuPix_S15]

Nice1 dude Get it fitted then you can push here a little more than stock... get the boost controller fitted and it's deffo new life for the car hehe

 

[crazymat666]

im in 2 minds of future plans for the car.
ethier buy a decent dumpvalve then save n get her mapped
or
buy the dump valve and boost controller n not bother with the mappin or actually do all 3 lol
hhhmmmm decisions?
off the subject abit but dont spose any1 knows which fuse is the abs 1 do they?

 

[DeanS15]

http://download.s15oc.com/s15_fuse_diagrams.pdf

 

[70YSR]

On the topic of strange boost readings, i had a problem a few months ago when i pulled my car out of the garage. went to pull out around a car, dropped it back to 3rd and found it peaked off the gauge and started boost spiking. Scared the crap out of me thinking i was going to break something. However it has a mechanical 2 stage boost control. So on high boost rather then sitting on a steady 13psi it was going to like 22, but the flick it over to low and it ran a solid 7 all the time. I came to a conclusion that the boost control was either broken or clogged... so i just bumped up my low boost to 10psi which i have been running and have no problems there. But on high boost instead of running 13 it gives different readings, If i am already in gear and put my foot down boost will climb properly out to about 11 (which is where its set atm) and hold steady. But, If i'm in a higher gear and drop back it peaks to about 17 then drops off back to 11.... Why would it be peaking like that? I am thinking about changing it to an ebc as i've heard mechanical ones can have problems... just wondering, any help appreciated.

 

[crazymat666]

http://download.s15oc.com/s15_fuse_diagrams.pdf

thank you im guna go find the footwell fusebox nw lol

 

[crazymat666]

right heres the situation

i just removed the abs fuse from the footwell and the breaking it loaaddss better no judderin or locking up etc just hard breaking finally but the speedo is run threw the abs so i have no speedo si the fuse is back in for now lol.
there are 3 fuses
1 in the footwell which is marked ABS(the 1 i removed)
2 under the bonnet fuse box marked ABS and ABS/ACT
would removing 1 of the other 2 help stop the abs but keep the speedo workin?

unless any1 has the answer to why its so bad in the 1st place?like abs pump knackerd etc?