Tuning a Rover Mini Cooper Spi
MM
without messing with the ECU?
Is there anything that can be to improve its performance without replacing
anything eg by tweaking some of the sensors to provide a richer mixer,
altering the breather hoses, tweaking the injector to raise the fuel
pressure?
Also can anyone explain the function of all the different sensors?
Thanks
MM
Michael Heinzelmann
the SPi ECU is able to handle about 80HP AFAIR, I once contacted my local
Mini Spare dealer for that and he recommended an upgraded cam, K&N, LCB,
RC40 and head. Don't know from memory which cam and which head but the
result would have been ~80HP.
HTH
Michael
"MM" <chart...@MTRAPbtopenworld.com> wrote in message
news:b4easl$c5g$1...@sparta.btinternet.com...
MM
> "MM" <chart...@MTRAPbtopenworld.com> wrote in message
> news:b4easl$c5g$1...@sparta.btinternet.com...
> > Is it possible to improve the performance (power not economy) of the Spi
> > without messing with the ECU?
> > Is there anything that can be to improve its performance without
replacing
> > anything eg by tweaking some of the sensors to provide a richer mixer,
> > altering the breather hoses, tweaking the injector to raise the fuel
> > pressure?
> > Also can anyone explain the function of all the different sensors?
>
"Michael Heinzelmann" <michael.he...@de.bosch.com> wrote in message
news:b4hfsf$q0j$1...@ns2.fe.internet.bosch.com...
>
> the SPi ECU is able to handle about 80HP AFAIR, I once contacted my local
> Mini Spare dealer for that and he recommended an upgraded cam, K&N, LCB,
> RC40 and head. Don't know from memory which cam and which head but the
> result would have been ~80HP.
>
Thanks for your comments. I know that there are performance enhancing
bolt-ons but was actually wondering what can be done to original parts to
enhance performance. One comment I read somewhere was that the fuel pressure
regulator can be altered to increase power (albeit at a severe reduction in
economy). It is tweaks like that that I am interested in. I don't expect
miracles from any tweaks, maybe 3-4 hp.
Regards
MM
Mark Cook
bhp, and i ended up melting a piston. I then had the engine rebored to
1293cc and rebuilt, then 6 months later melted another piston! It was only
then we realised the problem and binned the fuel injection system. That made
it much quicker!
cheers
mark
"Michael Heinzelmann" <michael.he...@de.bosch.com> wrote in message
news:b4hfsf$q0j$1...@ns2.fe.internet.bosch.com...
Michael Heinzelmann
> Thanks for your comments. I know that there are performance enhancing
> bolt-ons but was actually wondering what can be done to original parts to
> enhance performance. One comment I read somewhere was that the fuel
pressure
> regulator can be altered to increase power (albeit at a severe reduction
in
> economy). It is tweaks like that that I am interested in. I don't expect
> miracles from any tweaks, maybe 3-4 hp.
First I have to say that except some theoretical knowledge I have no
experience with injection Minis - when I was asking my dealer for this
tuning kit, I was about to buy a '94SPi but this deal never happened
unfortunatelly :-(
But I can tell you some things about the theory:
This one's also for Mark Cook:
IMHO altering the fuel pressure is cheating the ECU. When you raise the
pressure, the injector nozzle will inject more fuel into the engine as the
higher pressure will force more fuel through it in the same time.
Unfortunatelly, the ECU will correct this by decreasing the opening time of
the injector. So basically - nothing happens.
BUT - the ECU will need some time to correct this, so whilst this time you
might notice a difference, i.e. more power - if not too much fuel is
injected!! I don't know in what time schedule the Mini ECU works, maybe
youo'll notice that increase, maybe not?!?!
2nd BUT: At full throttle, Lambda control is usually switched off, so the
ECU will keep the injectors open as long as it's programmed for that given
rpm and throttle opening. So here increasing the fuel pressure will help.
But - how do you know if the mixture is still running within the limits,
i.e. not running way too rich? (Dyno session!!)
I've once spoken to someone on a meeting who told me that increasing the
fuel pressure does make a difference at full throttle.
Personally I would opt for the "classic" tuning beforehand, increasing the
fuel pressure is only if the ECU couldn't cope with the power that is
requested, and here we come to your problem, Mark:
I guess that your engine was running way too lean after tuning, this is
because the maximum opening time of the injectors is limited. This is most
usually a safety feature (if something goes wrong, the ECU makes sure that
no silly amount of fuel is injected) or limited by the hardware.
So the amount of fuel your engine will get is limited - if it demands more,
it'll run too lean.
Here raising the fuel pressure does help, as you'll get more fuel into the
engine with the same injector opening time.
But still - it requires a dyno setup to handle that correctly.
>> It was only then we realised the problem and binned the fuel injection
system. That made
it much quicker!
I wonder why no one has told you that your engine is just running way too
lean??? This problem could have been solved. But then I agree with you, that
a carburator Mini is way easier to tune...
Sorry for that long story...
Cheers,
Michael
MM
>
>SNIP<
Thanks again for your theories. that is the sort of information I was after.
I had heard that the ECU can learn but didn't realise that it acted
differently at full throttle. Do you know what the function of the sensor is
under the accelerator pedal, or what happens if the Lambda sensor is
disabled?
Sorry to hear about your problems Mark. I agree that carburettor induction
is better but I am curious about just how far you can go with the standard
set-up before making any major component changes.
MM
Graham
> I had heard that the ECU can learn but didn't realise that it acted
> differently at full throttle.
Most injected cars run open loop at idle and under full throttle.
When the throttle is in the idle position and the revs are over about
150% of idle speed they typically cut off fuel completely.
Under all other conditions they run "closed loop", meaning they read the
oxygen sensor and correct the mixture for lowest emissions.
There's no point in tuning for maximum power under part throttle, since
if you want more power you can open the throttle slightly instead.
> Do you know what the function of the sensor is under the accelerator
> pedal,
I'm not familiar with the Mini system. Most systems have a throttle
position sensor at the throttle body.
> or what happens if the Lambda sensor is disabled?
The computer soon works out that the oxygen sensor isn't behaving
correctly, logs the fault, turns on the fault warning lamp and goes into
a limp home or work-around mode to do the best it can with inadequate
data.
To repeat: There is no point in trying to trick the system into running
rich all the time to get more power. You'll just finish up using more
fuel and making more pollution. To improve power you only need to
influence maximum throttle power. At maximum throttle the system ignores
the oxygen sensor.
> Sorry to hear about your problems Mark. I agree that carburettor
> induction is better
Luddite.
Electronic fuel injection is vastly superior, more reliable, consistent,
economical, cleaner. It also forces the very very few people who want to
modify their motors to learn a bit about it to make it all work. Given
that the vast majority of cars end their lives with no modification more
sophisticated than a new keyring from the local garage thats hardly a
big consideration.
> but I am curious about just how far you can go with the standard
> set-up before making any major component changes.
Just as you need to understand carburettors properly and use a chassis
dynomometer (rolling road) to make the most of a modified carby car, you
need to understand EFI and have the right equipment to modify an EFI
car. An EFI car with oxygen sensor and knock sensor is the nearest thing
yet to a permanently tuned car.
MM
"Graham" <zeb...@alphalink.com.au> wrote in message
news:3E6E04B3...@alphalink.com.au...
> snip
>
> There's no point in tuning for maximum power under part throttle, since
> if you want more power you can open the throttle slightly instead.
>
Thanks for your comments Graham. I've read your comments before and as usual
you've hit the nail on the head. Sorry that you think I'm a luddite though,
it's just that as far as out and out performance on the race track is
concerned carburettor induction mini's seem to vastly out perform injection
mini's - at least here in the UK.
MM
Shaun
usual
> you've hit the nail on the head. Sorry that you think I'm a luddite
though,
> it's just that as far as out and out performance on the race track is
> concerned carburettor induction mini's seem to vastly out perform
injection
> mini's - at least here in the UK.
The only real problem with trying to modify a standard EFI car is that the
fuelling map is fixed, it's equivalent to trying to modify a carbed car
without being allowed to change the needle. If you can move to mappable EFI
(ŁŁŁ) you can make it do whatever you want and properly setup will easily
match and probably better a carbed car.
Shaun.
Michael Heinzelmann
> fuelling map is fixed, it's equivalent to trying to modify a carbed car
> without being allowed to change the needle. If you can move to mappable
EFI
> (ŁŁŁ) you can make it do whatever you want and properly setup will easily
> match and probably better a carbed car.
I wonder that no one has ever produced a "fully adjustable" ECU - at least
I've not heard of one.
For popular cars like VW Golf or so those are avaible. Of course you still
need a dyno session and someone that is veeerrryyy experienced (as you need
a basic setup to start with)...
I believe that Mini Motorsport has made an upgraded ECU for the SPi mid
'90s. A friend tried that on a std. engine but it was no good, worse pull
than before and lumpy idle.
Does someone know what ECU (i.e. manufacturer, type) and injection system is
installed in the xPi's?
I really would like to dig in a bit.
Cheers,
Michael