Airmiles

Is this JUST in 2nd?

I only ask because I had fairly feeble response in 3rd in a similar situation couple of weeks ago. Though it could have been due to 3-up plus loads of gear....

Pete Croney

This problem has troubled Impreza owners for years. Lifting off and reapplying always gave full boost, but why did the problem occur???

The answer is that the ECU has an algorithm to help the car through emmision tests.

Part of the test requires the car to be driven between two points under full acceleration. The noise is then measured.

The ECU designers have programmed it to know that if it is held on a steady throttle for between x and y seconds, then it is a noise test and only to give 0.5 bar. Clever or what?

The story was related to me by a member who was at a lecture, held by some of the worlds OE ECU mappers. Apparantly they all do it, not just Subaru.

The P1 was also an interesting one. To pass the noise test, it needed to utilise the extra 1dB allowed for "supercars". To make this category, it must add a minimum of xx km/h over the set distance. It couldn't do it, but was too noisy for the standard noise limit, even with the half boost trick.

I'm sworn to secrecy about how they did it, but it did make the "supercar" category, with a perfectly legal modification.

Oh... and if the tests hadn't been done in 1999, it would have never passed the stricter 2000/1 tests and would not be on our roads at all.

Next time you drive your P1, you can have an even bigger grin on your face

JoeyDeacon

Suddenly everything is clear.....

I have a UK MY00 Impreza and had been wondering why if I kept a constant part throttle up to about 3000RPM in second (So the turbo was just beginning to spin) and then floored it I didn't get the expected instant power (Due to the turbo not having to spin up).

To be honest I thought it was a problem with the car as it just seemed to happen randomly, some times the power was there and sometimes it felt gutless!

jack

Do you guys conduct noise tests with the car on the go? Here in Singapore, the car is stationary when the test is performed. A microphone is put a fixed distance away and the engine is revved to 6000rpm. Passing rate is 92dB or something. No boost all this while unless you have launch control/anti-lag on.

BHORT

This was the reason that my dealer gave me some time ago. Now that we know the answer is there anything that can be done to change the way in which ECU works rather than modifying the way in which people drive.

Brendan

mattski

so lemme get this straight... putting
your foot down, easing off and
reapplying will give you max boost?

Is there any particular point revs-wise
this should be done?

JoeyDeacon

mattski,

What happens is if you slowly accelerate in second at part throttle and then floor it you only seem to get half boost. I think what you need to do is first lift off the throttle and then floor it which fools the ECU into giving full boost.

[This message has been edited by JoeyDeacon (edited 16 November 2000).]

Mr Leigh

Well its still a cr4p design and along with the crap visual design is a good reason not to buy a MT01 Subaru.

AndrewC

If this is true (and I am sure Pete wouldn't have posted it if he didn't believe it) then this puts to rest several previous threads such as

mattski

kinda reminds me of the old Triumph 2000s
'kick-down'

oh boy am I going to have a fun drive home...

are we talking about lifting off the throttle
completely?

[This message has been edited by mattski (edited 16 November 2000).]

GaryC

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:<HR>Originally posted by AndrewC:
<B>

Does anyone know if the PPP still has this built in boost limiter?

AndrewC...[/quote]

My MY99 PPP suffers from the same trait, normally in 3rd and 4th gear, but thinking about it, it is normally when I have held revs constant for some time, waiting for the oncoming traffic to clear - you know the script

Thanks Pete - I had been wondering whether this was a fault with my car, dealer didn't seem to know anything, and has been cleaning the wastegate for the last 12 months to try and fix it

Mind at rest - I hope!!

IWatkins

MMMMmmmmmmmmm, interesting.

Same symptom and same fix for all models of Toyota GT4 too. Contant throttle, back off then floor for max power.

If just constant then floor it, then the car feels very retarded until lift and then floor. On my GT4 you only have lift (all the way) for a millisecond then floor it to get past this 'fault'. Is it the same for Scoobies ?

Maybe, for the same reason too.

And there is me spending god knows how many hours messing with this trying to fix it. Been looking at sensors, fuel flow, all sorts trying to sort it.

Cheers

Ian

SCOTTY

When I am about to overtake, but waiting for a stream of oncoming traffic to pass I drop back and into 2nd and lift completly off the throttle and back on a few times before I floor it and it absolutely flies past my victim in front
I then normally get flashed at because of the gorgeous roar of my Scoobysport backbox scares the crap out of them.

Scotty.

PS: Thanks Pete. I often wondered why sometimes my car felt dead when I just held the revs before flooring.

Darren king

This explains perfectly the way my my93 WRX behaves......and i was convinced it was a fault somewhere, question is would lets say a 'unichip' cure the fault.

Daz.

mattski

good question, do ECU replacements
generally make the car boost as per
the lift-off game or is the significant
increases generally found through
the remaps and so forth?

tizard99

Intriged, My boost gauge always goes round to 0.8 Bar even when I floor it? Although I do find in first the car seems to be restricted in some way (is this something in the ECU to save the transmission I wonder? - see

robski

Surely the ECU would dictate how this worked?

If its a total replacement it cant continue, but if its a piggy back jobbie, its still at the mercy of the original programme to some extent?

Sunil, have you still got this with the link?

What about the prodrive chip, maybe this is one of the reasons why its a lot faster (I.e. remove this limitation)!?

robski

Trout

iTrader: (1)

We need to reinvogarate Pat - I am sure he could get Link to do this

R

AndyMc

Hi

I have discovered the exact conditions which make my my98 give half boost.

It's a bit complicated but here goes.
It does it between 38-42 mph following a change to second gear from forth so long as you stay at the same speed and hold the revs constant for more than about 1 second following the gear change before you floor it.

If I change down from third or fifth or at a higher or lower speed or if you don't keep the revs constant it does not do it, and I can only make it do it in second gear.

It would be interesting to see if other peoples cars do it under the same conditions as mine,anybody want to try it?

Ps I've just had a thought ,imports with converted speedos will probably be different due to the altered speed signal seen by the ECU.Anybody with a UK car want to try?

Andy