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Old Oct 18, 1999 | 09:03 PM
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please can anyone help i just fitted a APEXI boost controller to my sti 5 but cannot raise the boost above 1 bar is there some special way of raising the boost on the sti 5 P.S. has anybody got a wiring diagram for the E.C.U.
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Old Oct 18, 1999 | 10:08 PM
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Howdy...

How/where have you plumbed the system in ? By the sound of it the ECU is fighting the controller and winning (maintaining the boost)

J.
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Old Oct 19, 1999 | 11:00 AM
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Maybe the ecu boost limit is still functioning. Generally boost controlers don't do anything to the boost limit, so a Fuel Cut Defencer (HKS) or similar unit may be required to raise the boost limits.

STI 5 cars are having enough problems with fuel/high revs in the UK, I would not raise the boost level until you can sort the fueling and ignition out properly, unless you have access to a ready supply of >100 RON fuel.

If in the UK, keep the boost controller on standard limits, use it to help the car maintain boost, unless you sort the fueling and timing.

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Old Oct 19, 1999 | 11:31 AM
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This sounds like a recipe for disaster..

STI V's have a ECU optimised for 100RON (Jap spec)fuel and have been known to suffer problems when driven hard on UK fuel.

Until a UK company has re-mapped the ECU I would say you're playing with fire.

However if you're still keen to melt a piston...

firefox does sound correct..the boost controller clearly isnt winning. Surely the boost controller should replace the ECU controlled system..sounds like a plumbing problem.

Also, you will not get more than 1.2 bar without the ECU cutting the fuel. This can be "fixed" by using an overboost defender (superchips), but then the ECU will not see 1.2 bar it will see 1 bar and provide wrong fuel/ignition.

So let me see..STI-V on non-100RON fuel, raised boost, wrong fuel/ignition...please dont be silly.
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Old Oct 19, 1999 | 07:47 PM
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SORRY GUYS i forgot to mention that i am also going to use a APEXI SUPER ITC (ignition timing converter)APEXI FUEL CONTROLLER and EXHAUST TEMP GAUGE and i always use super unleaded i have been told the boost limiter cuts in at 1.5 BAR and i am hoping to get my car upto 1.4 BAR with all these mods!
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Old Oct 19, 1999 | 07:48 PM
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SORRY GUYS i forgot to mention that i am also going to use a APEXI SUPER ITC (ignition timing converter)APEXI FUEL CONTROLLER and EXHAUST TEMP GAUGE and i always use super unleaded i have been told the boost limiter cuts in at 1.5 BAR and i am hoping to get my car upto 1.4 BAR with all these mods!
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Old Oct 19, 1999 | 09:33 PM
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Umran,

A standard Impreza turbo cuts the boost at 15.5psi (1.06bar). I believe that the STi5 also runs similar limits as standard.

The STi5 also has well-publicised problems with detonation - so if you are going to do this, I would strongly urge you to get all of the gear fitted at once and by an expert!

I would recommend that you look at Paul Strong's dyno site (http://start.at/dyno) and look at the cars shown (and the boost they are running - standard and modified).

I had a look at the STi 5 models on there - and the highest boost I saw was 18psi (1.22bar) on one car - average peak boost was 2psi lower on all of the other cars.

Sensible boost levels have been used and AFAIK all the cars are still alive!

Good luck and be very, VERY cautious!

For example, whoever told you the ECU cuts out at 1.5bar obviously does not know what he or she is talking about - get ready for a BIG bang!

Thanks

Gavin

[This message has been edited by GavinP (edited 19-10-1999).]
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Old Oct 19, 1999 | 11:58 PM
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Hi there...

The figure of 1.5 is wrong... its cuts below that.

As stated there have been problems with Version V's....

The Apexi kit combination is good.. but needs setting up very carefully... the EGT is a good device to use... but a rolling road with exhaust sniffer is better...

1.4 is too high... I have been running 1.4 on my IV...with water spray and injection... and the correct fuelling.. but I wouldnt go that high on a V.... I have actually dropped it back to 1.3...

The STi V has a smaller turbo than the IV... chances are at that level, its past its optimum level..and is just generating heat...

J.
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