hmhaga

On Saturday I was supposed to participate on a track day session, the track is a 3 hour drive from home. After 1.5 hours of driving the Dawes Device caused fuel cuts, after 2 hours I realized I had forgot my helmet at home, after 2.5 hours the constant noise from the Magnex silencer gave me a terrible headache. So no track day, when I got back home I immediately 1) Removed the Dawes Device 2) Removed the boost meter 3) Removed the magnex silencer. I decided to leave the downpipe.

Equilibrium - ahhhh :-)

john banks

What boost were you running with the Dawes and what model/year is your car?

SSE

Howdy, newbie!

So Magnex bb AND Dawes goes to me then?


Simen.

john banks

If you set a Dawes to 1.1 bar on a MY98 you are asking for a fuel cut. This would be the sensible limit on a MY99/00 which have a higher fuel cut.

Yes it does vary boost in extreme loading, hence why you should run a good 0.07bar or more lower than fuel cut.

You would have exactly the same problem with many EBCs as well.

SSE

hmhaga.....
Holy smoke! Did it cut while longside a 20 meter truck, or...??

I was looking forward to a ride with your Dawes-modded motor next
weekend, but I guess we'll have to do some 'experimenting' with
mine instead, then Have you already removed the gauge?
What boost is it peaking/holding without the Dawes?

Mine is peaking almost 1.4 then immediately settling at 1.0
steady, dropping off from about 5500. Would like to check if the
Dawes could remove the spiking, as this doesn't feel right.
Moreover, the car is also hesitating under acceleration in fifth,
and the Dawes could probably rectify that as well.
On WOT from low-/midrange in 4th (when car/engine/bbox is nicely
warmed up ) the boost is also fluctuating in long pulses.
Suspect Dawes will fix that as well.....
Only thing I am a bit worried about is the light throttle/
full boost situation - Will have to get hold of an AFR meter.

Re your backbox;
Had a long, nice trip this weekend (nice, bar the GBP 250,- ticket
for speeding :O ) and I believe the Remus BB will suit you just
fine. There's no way you can drive around with those cigarillo-
pipes sticking out the back

Simen.

[Edited by SSE - 3/4/2002 8:56:48 PM]

hmhaga

>Holy smoke! Did it cut while longside a 20 meter truck, or...??

No, while chasing a F..d Cosworth. I lost

Without the Dawes, it peaks at 1.1 bar and holds 0.9 bar. What IS the fuel cut limit on the MY98?

john banks

1.1-1.15bar from what I hear. MY99/00 is about 1.2bar. MY99/00 PPP is about 1.35bar - so I run about 1.25bar and never had an unintentional fuel cut running at this level.

The boost level on the MY99/00 has to be held for about 4 seconds before the fuel cut so test with this in mind.

If you know where YOUR fuel cut is on YOUR gauge you are sorted - go 0.07bar or 1 PSI back from fuel cut on the HELD boost under full load in 5th gear from 2000 to 5000RPM as a test.

As you have it now as standard a 0.2 bar peak over held is a bit much - it can easily start oscillating. This could be because of your downpipe? A big peak is fine if you are well away from fuel cut, but I like to keep the peaks small and short and run the most held boost possible.

Taking the Dawes off will delay your spool up and it will drop more at the top end, even if you only run 0.9-1.0 bar held on your gauge - it will hold it as long as the turbo/actuator setup will allow.

[Edited by john banks - 3/4/2002 9:24:00 PM]

SSE

John,

When referring to the orifice, I guess you mean the bleed hole
in the Dawes? I don't run Dawes, but the ECU has been re-programmed
(so they say, the company who modified it.) It's set to hold
1.0 bar and so it does, once it has stabilised from its somewhat
sky-high peak at 1.4, that is. Never seen any sign of boost-cut.
Car has decatted centre section, Remus Backbox, KN panel.
After the ECU mod I have later fitted decat big bore single DP
and removed the intake resonator.


Just a bit more info on the ECU (Not that I think it's very
relevant here, but anyway - since I guess you're a curious guy....)
The company who did it, is a specialist company for car
electronics, and known to be serious and trustworthy.
Car importers direct to them for remedy when their cars
have 'black-box' failures.....

I did not have much knowledge about the Scooby when I had the mod
done, but I did know that 'people' said the 99-00 ECU is
impossible to remap. However, this company stil claim they remap
fuel and ignition etc in the original ECU, and only increasing
the boost marginally.

There is no physical sign of any surgery in the ECU. (And no
bleed valves or similar stuff in the engine bay...)
When enquiring about the unstable boost, they say the Scoob's
boost control is poor by nature, which is again more pronounced as
the boost is upped compared to standard.

Later, I have asked how it can be that a small company in little
Norway knows how to remap the 99-00 ECU when no-one else but
Prodrive does. They actually reply this is due to a co-operation
with Prodrive over many years etc etc and that they actually have
assisted in developing ECU software for Prodrive which is being
sold in UK for street use. (I assume this can only be the PPP ECU
mod, but I have SERIOUS doubts that this can be the case!!!)
On a side note: This company DO service both a 1999 Impreza WRC
and a 2001 WRC (Petter Solberg's old car) so that there can be
some connection between them and Prodrive is fair enough, I guess.

Anyway, I still have a feeling that they're talking rubbish,
but what can I do about that...
Mike Wood - if you read this post, you may want to comment.

Regards,
Simen.

[Edited by SSE - 3/4/2002 10:16:52 PM]

SSE

No doubt the boost control is crap.
And it became even more noticeable after fitting the big bore DP.
The hesitation in 5th has been there all the time.
Also before the ECU fiddling, which was carried out late autumn 2000.

I think I'll go another round with the garage to get to the bottom
of this matter....

Simen.

john banks

I think so. What you describe are not the hallmarks of a well remapped car. Full remapping includes boost too.

The std ECU has a lookup table based on throttle position and RPM for a duty cycle it sends to the solenoid. After spool up there is a second map with boost targets. If this has been remapped it should work perfectly. If they can remap timing and fuelling then surely they can get the boost right. Prodrive's PPP is fine (as long as you get the right restrictor!). The Subaru MY99/00 ECU setup is quite fussy about the right restrictor from what I have observed, but get it right and it is not bad at all.

hmhaga

MY98. Boost set to 1.1 bar in 5. gear up a steep hill. Is the Dawes affected by temperature or air pressure? ...as it suddenly decided to "change" the boost limit.

SSE - you can have the Dawes for free. Fuel cut while overtaking can get a bit too exciting. The Magnex is not getting back on either


[Edited by hmhaga - 3/4/2002 8:31:11 PM]

john banks

The boost oscillating and the 0.4 bar peak suggest that the orifice could be blocked with oil or is too small, or a hose is split. The boost control has become underdamped. What oil level do you run? Have you removed any cats from your exhaust?

The part throttle/high boost issue can be virtually eliminated with the bleed hole increased to 1.5mm - see the FAQ link in my profile for more.

If you set your car up properly with or without the Dawes you should have consistent, smooth, spike free boost without fuel cuts.

Also note that a lot of boost gauges under report the boost by up to 0.1bar, so you need to either calibrate your gauge or find fuel cut and turn back a bit depending on how sympathetic you are. If you set for 1.1 bar you could be 1.2 bar, plus high load 1.3 bar = fuel cut inevitable.

[Edited by john banks - 3/4/2002 9:02:00 PM]

john banks

The MY99/00 ECU IS now reprogrammable - prototype Delta ECU that Stephen Done mentioned in a thread about different ECUs and PE were mapping it, but it is not YET available commercially.

Prodrive for their PPP give you a new STi badged ECU which has been reprogrammed (I have one).

If you ECU is reprogrammed then what the hell is it doing with a 1.4 peak 1.0 bar held. That cannot be good tuning in anyone's book and even Subaru's boost mapping is not that bad!

I could get the same boost result on a MY99/00 by filling the restrictor orifice (in the line off the turbo outlet) with solder and redrilling it to 1.0 to 1.1 mm instead of 1.2mm. A quick peak would not give you fuel cut, but the ECU might oscillate the boost. Obviously I don't know what they have done with the fuelling and timing, but that boost control is frankly crap.

There is also a bleed hole on the Dawes - different issue entirely.

However, you fitted the downpipe after the ECU mod - it is not surprising that you have a large peak - you can solve it by making the restrictor orifice LARGER on MY99/00, but only by about 0.1mm - get a precision drill set or an adjustable valve to replace the restrictor - see thread in the FAQ link from my profile.

[Edited by john banks - 3/4/2002 10:34:35 PM]