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Old 05 December 2010, 05:52 PM
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mazmike
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Default boost dropping off

i am running 1.8 bar boost but at higher revs its dropping off to 1.5 what can it be what do i check cheers mike
2.1/ sc46 451bhp/ fmic /3 port/ fpr/rcm 3" ehaust /hks bv/ 1997 sti ?been told it could be silecon inlet hose sucking closed?
Old 05 December 2010, 05:57 PM
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banny sti
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Could be the silicone hose sucking shut or dv leaking.... What air filter are you running?

Banny
Old 05 December 2010, 05:59 PM
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hks fillter hks dv but tryed aps dv and it was the same

Last edited by mazmike; 05 December 2010 at 06:00 PM.
Old 05 December 2010, 06:02 PM
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kiranbaloo
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mine did that and it was a split in one of the silicone joiners in the fmic pipework
Old 05 December 2010, 06:03 PM
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mazmike
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what hose is best i think i have a cheap one on
Old 05 December 2010, 06:06 PM
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kiranbaloo
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I dont think it makes that much difference as it is just to join the metal pipes on the fmic on mine it was behind the front bumper it had been rubbing on the body work and put a split in it you could tell where it was leaking as there was an oil mist around the area where it was.
Old 05 December 2010, 08:41 PM
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dunx
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Was it mapped like that to be safe ?

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Old 05 December 2010, 09:02 PM
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@dunx no mate just keeps droping off starts at 1.8 then goes to 1.5 my map is on the last page of s/c theard
Old 05 December 2010, 09:17 PM
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Terminator X
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Mine used to do that & turned out to be boost controller set up in-correctly ... wasn't wired up to monitor revs & throttle pressure Once wiring was sorted a few tweaks to the unit & all was well.

TX.

PS

Here is mazmikes graph from other thread:

http://i740.photobucket.com/albums/x..._Image0002.jpg

PPS

450hp seems a good result from lowish boost!

Last edited by Terminator X; 05 December 2010 at 09:22 PM.
Old 05 December 2010, 09:22 PM
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sorry m8 but what is the boost controller and where is it i have a simtec ecu
Old 05 December 2010, 09:27 PM
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We'll need one of the technical guru's to reply I guess My car runs an Autronics ECU & a HKS EVC VI boost controller. It wasn't holding the boost flat to the redline ... was peaking at 1.8 then dropping quickly to 1.5. It now peaks at 1.9 & holds 1.8 to the redline.

TX.
Old 06 December 2010, 07:16 AM
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MartynJ
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Originally Posted by Terminator X
Mine used to do that & turned out to be boost controller set up in-correctly ... wasn't wired up to monitor revs & throttle pressure Once wiring was sorted a few tweaks to the unit & all was well.

TX.

PS

Here is mazmikes graph from other thread:

http://i740.photobucket.com/albums/x..._Image0002.jpg

PPS

450hp seems a good result from lowish boost!
Thanks for the comments re power for boost, we were quite happy with the outcome and the car goes like stink.
On Mikes car the boost is being controlled through a Prodrive 3 port solenoid and the SimTeks internal boost control. This has rpm dependant settings and has been maxed out at the top end to try and stop the drop. As Mike has mentioned, we suspect that the inexpensive intake hose could be sucking shut at high boost/rpm demands (And this wouldn't be the first time we have seen that), or that excess back pressure in the exhaust could be opening the wastegate.
The intercooler system has recently been checked for leaks and is leak free.


Martyn
Old 06 December 2010, 09:38 AM
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mazmike
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Originally Posted by Terminator X
Mine used to do that & turned out to be boost controller set up in-correctly ... wasn't wired up to monitor revs & throttle pressure Once wiring was sorted a few tweaks to the unit & all was well.

TX.

PS

Here is mazmikes graph from other thread:

http://i740.photobucket.com/albums/x..._Image0002.jpg

PPS

450hp seems a good result from lowish boost!
yes mate well happy with 450hp its not worth spending any more money on it to get more hbp as its a fast car on the road now .just trying to sort out the little things now .as martin said looking to re place the inlet hose now .seen one at scooby clinic
Old 06 December 2010, 10:26 AM
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banny sti
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If you need a 76mm one, I have lateral performance one for sale
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