Is This Right? Boost Controller Installed..

[Wacky Dee]

Got a Greddy EBC installed the other day by CRD .. they dynoed it a few times to find the best 'high' setting and apparently the highest the stock ecu would do without making funny stuff was 10psi (with 11psi there was a huge dip in the power curve)

Anyway, I drove with the hi setting around since I got it as 10psi is safe enough etc. However I've noticed on the boost controller's display the boost goes from -99 to very low positive values and it goes up and down as I shift through the gears.

Is this normal? is it supposed to hold full 10psi boost ONLY when I'm at full throttle? ie. only once I hit 3000rpm and my revs stay at above 3000rpm ie. not around town where you constantly have to shift down and can't run full throttle.

I'm a bit confused about whether the ebc is supposed to hold at half and less throttle or just at full throttle .. as it is currently, most of the times it displays negative value between -99 and -10 and it goes up and down fast as I'm driving. If I put the foot down a bit it tends to go into the LOW positive values 10 or 20 (ie. 1 or 2 psi) but it goes down quickly..... but this is all around town.

Maybe my understanding of how boost works is all wrong and this is all normal.

By the way - would you guys recommend CRD to tune a powerfc on an R34 GTT ? They said they'd do it for $650 which seems cheaper than anyone else. I just scored a pfc via japanese auctions for less than $300 total using importmonster.com.au

[NYTSKY]

lol thats normal mate.Its reading the vacuum. The price they quoted you is cheap because you have minimal mods.

[paulr33]

yeah controllers go from negative pressure then into positive pressure

usually its -760mhg then to 0 then they go into positive, so like 0.30kgcm2 0.40kgcm2 and so on

[Wacky Dee]

i've actually switched to psi mode so the values are between -99 and supposed to go up to 100 (positive) since 10psi would display as 100 (the whole x10 thing with greddy ebc)

from reading other threads on the topic and the manual for my ebc, I got the impression that once I get boost ie. running above 3000rpm, the EBC is supposed to hold the boost at 10psi STEADY ... but I haven't seen it steady yet.

Is it supposed to be steady only at full throttle ? I seriously don't know how boost works .. all I know is I hear the turbo spool up when I gun it a bit (1/2 throttle or so) and reach about 2700rpm.

Another issue ... when I had the car dynoed recently, we lost boost at one of the dyno runs .. mechanic said the wastegate actuator got stuck open, that's why. Apparently due to the aftermarket dump pipe not lining up 100%. I'm a bit worried about this causing issues constantly .. is the actuator likely to get stuck open again if it's done it once before?? What should I do about it? How would I know if it does get stuck?

[paulr33]

do you mean kpa? not many boost controllers display in PSI, most are kgcm2 or mmhg or kpa

but turbo charger pressure will increase as engine load does, so when the engine is on load, it should reach target boost quickly and be stable

[Wacky Dee]

no, EBC has an option to display boost pressure in PSI apparently but it displays it in x10 eg. 10psi should show as '100'.

Can you please explain what you mean by load?

[GeeTR]

Load, as is the resistance to the tourqe being developed by the engine.

As the turbo blows against the motor, pressure backs up, thats boost. Higher gears / big hills cause "load" or resistance on a motor -> which causes boost to back up quicker -> which causes increased exhaust flow -> in turn more boost.

This is why when you mash the throttle at 100 in 4th your making target boost earlier then if you were rolling at 40 in 2nd.

Edited May 26, 2008 by GeeTR

[Wacky Dee]

I see .. so the EBC is not meant to hold boost at 10psi around town even if you were gunning it in 2nd/3rd gear - only when under CONSTANT load, ie. highway, hills etc? Think I need to get onto a dyno and test this ..that is if anyone would actually let me sit in the driver seat when on the dyno.

Edited May 26, 2008 by Delta Force

[GeeTR]

Umm, not it was more of an example for cars with manly sized turbos. Your stocker should be able to hit 10pound pretty quick in any gear when the peddles mashed.

Edited May 26, 2008 by GeeTR

[Wacky Dee]

hmm well .. according to the greddy ebc display it RARELY even goes into positive values and I haven't seen the values steady once - it just keep going up and down and it's usually in negative values (ie. under 0 eg. -45)

Could it be that

1) the ebc lcd display is just dodgey or not connected properly ie. not displaying the boost pressure properly?

2) my wastegate actuator is bloody stuck open again and I'm not making any meaningful boost?

I tried gunning it just before when there was no traffic around ..was doing 4000-4500 rpm in 2nd and 3rd gear and the lcd display was showing value ranging from like -30 to +15 but quickly going up and down .. eg. as soon as it reaches positive numbers, if I shift it drops down into negative numbers again.

I am so confused ... don't know if it's just a display issue or if my boost is not working properly ie. actuator stuck open again

Edited May 26, 2008 by Delta Force

[Duncan]

don't worry mate that is perfectly normal. you will get 10psi by 2500rpm with good load, but in normal driving you just can't hold your foot flat long enough to see it before you get the redline or speed limit. best place to see it is a long hill in say 3rd

btw yes profec b shows psi, and -99 is good, at idle it is generally higher like -80. the lower the number at idle the healthier the motor (better compression)

[kittykat11]

but when i start my car, at idle, it only reads between -.55 and -.70

[Wacky Dee]

mine reads about -80 at idle when the engine is completely cold ..but once warmed up its always -99 at idle. Good to hear that's a good sign

But I'm pretty sure something's not right .. most threads I've read about EBCs, people are saying their ebc holds the boost at precisely the preset boost once they get boost which is usually after 3000rpm. Just today I read a comment by someone suggesting a lower psi to someone for around town otherwise his fuel eco would be shit as his boost would always be 10psi...

I don't think I've come close to 10psi which is what my ebc is set to.

I've tried gunning it on the motorway and I get very quickly fluctuating values mostly in the negatives. Gonna have to put it on a dyno as it's friggin hard to read the lcd whilst driving on the road (and dangerous)

The thing that worries me the most is the wastegate actuator getting stuck on open position .. it's happened once when the car was on a dyno. Mechanic said it's probably due to the aftermarket dump pipe sitting 100% correct so the flap gets stuck open. Now whenever something doesn't seem right I keep thinking it's that bloody actuator stuck open again, esp. with being unable to get the '100' (10psi) with the ebc whilst driving on the road.

Any way of making sure the actuator never gets stuck in the open position? I don't wanna take it back to the place that installed my exhaust as they might find the actuator isn't stuck open and go '"everything seems fine, that'll be $100 for wasting our time" and make me look like a douchebag.

Edited May 26, 2008 by Delta Force

[10MinuteCar]

greddy ones can be converted into 'PSI' from 'KPA'

[Wacky Dee]

the figures above are in PSI (x10) ie. psi of 5 would show up as 50.