GT-FOUR Celica!!! BC not working!!!

[ST185 Celica]

Hey guys,
Ive been trying to install a boost controller and its not working, it starts to spike. I have heard the it needs a FCD... Is it true??
If so then where would the FCD be located???

Cheers

Josh

[Roundy]

FCD=Fuel Cut Defender. It needs to be made up (or you can remove the line that makes the std boost gauge work)

The spiking is likely to be caused by the exhaust. The gases are finding it easier to go through the turbine wheel then the wastegate, hence the boost will spike.

When i had my CT26 with the 3" Dump Pipe it could boost to 14psi with no boost controller and the TVSV disabled!

[ST185 Celica]

how the hell is that possible???
How did you make it happen???
Would love to be able to boost it right now!

[Jorrs]

is it an Electronic boost controller ? or a manual bleed valve.

[Roundy]

i don't know how it was possible, it shoulda cut at 12psi (and frequently did) but sometimes it could get to 14psi without cutting out

what do you want to boost to?

11psi is very safe, don't have to mess with the FCD or anything and has ample fuelling there, sure the occasional spike might see you hit the fuel cut tho!

Also when changing gears sometimes the manual boost controllers have a bit of lag time and take a while to open the wastegate, on my current setup i spike ~1-1.5psi after a gear change (when into it of course) which puts me right on the brink of the Fuel Cut.

[ST185 Celica]

manual is all i have atm... but im looking at gettin a EBC!!!! but im only looking for one for bout 4 - 500!!!

[ST185 Celica]

ohk well i put the GFB BC on and set at stock 7psi and it ended up spiking on me
Im looking at raising it to bout 11 or 12 cos im bout to install a FMIC it arrives tomoro!

[Roundy]

well that sounds like it could very well be the free-flowing exhaust causing it!

safest course of action would be to try to limit boost for a little while, get a FCD installed (you can learn how to make one here which i believe is applicable to the 185) or you can buy one for $$

after that take it to a dyno, and keeping an eye on the AFR's see what boost it will hold, and if all is good with the AFR's at that boost level set it there.

however i think anything more then 14psi your engine could be living on borrowed time anyways

Cheers
Nathan

[-==L=a=N=c=E==-]

or an easier method is to just disconnect the vacuum hose to the MAP sensor.

No more boost cut, and your stock boost gauge no longer works (useless anyway)

although all the above applies too

[spectral]

i don't know how it was possible, it shoulda cut at 12psi (and frequently did) but sometimes it could get to 14psi without cutting out

Most likely you were measuring boost at the turbo, not at the manifold? If you take your boost reading from the same spot as the ECU does then it will cut at 12psi. If it doesn't someone has done the 20cent zenor diode FCD mod to your ECU.

An aftermarket dump pipe does help reduce spiking if it is made properly with better flow around the wastegate area.

[ST185 Celica]

is there an aftermarket dump pipe available for the st185 celica ???
Is it best to make one yourself ???
i.e - 3" dump then 2.5" to cat, then 2.5" to a 3.5" cannon
Would that be the best performance exhaust ??? ( If not what would it be ??? )

J

[spectral]

Heaps of aftermarket dumps available.

Aussie Exhaust are probably one of the best quality and they are locally made.

If you are after a cheap solution then you can get the chinese ripoff of the Aussie design off ebay.

I'd go 3" all the way through. Aussie exhaust have the entire kit, and from personal experience, the Aussie products work very well.

http://www.aussie-speed.com/buyonline/showCats.aspx

[Aust162]

Most likely you were measuring boost at the turbo, not at the manifold? If you take your boost reading from the same spot as the ECU does then it will cut at 12psi. If it doesn't someone has done the 20cent zenor diode FCD mod to your ECU.

An aftermarket dump pipe does help reduce spiking if it is made properly with better flow around the wastegate area.

12psi is only an approximate value for the boost cut. The map sensor sends voltage to the ecu that triggers the boost cut. I think the value is something like 4.5v, so it can vary because there is no direct correlation between the voltage trigger value and the psi level.

Edit: but yes, mine seemed to cut very close to 12psi. Also the quality of the boost gauge will effect the accuracy of the reading.

[spectral]

12psi is only an approximate value for the boost cut. The map sensor sends voltage to the ecu that triggers the boost cut. I think the value is something like 4.5v, so it can vary because there is no direct correlation between the voltage trigger value and the psi level.

Edit: but yes, mine seemed to cut very close to 12psi. Also the quality of the boost gauge will effect the accuracy of the reading.

Agreed thats its voltage that triggers it.. but all the MAP sensors would be very close to giving the same voltage at a given pressure, so in my opinion, its accurate to say boost cut occurs at 12psi.

Its certainly more useful to say to someone "you can only boost about 3psi more than stock", than say "You can boost until your MAP sensor reads 4.5V"

[Aust162]

Its certainly more useful to say to someone "you can only boost about 3psi more than stock", than say "You can boost until your MAP sensor reads 4.5V"

I agree