After market boost controllers??

[Rusty]

So what gets replaced by these on a standard ABY? Does the MAP sensor and N75 go and get replaced by a MAP cheater and a boost control solenoid?

[Jamo]

Not quite, the ECU is just disconnected from the boost signal and then boost line goes to the boost controller and controller has it's own controlling solenoid to the wastegate.

[S2central.net]

Uhhhhh - I don't get that bit... If the ECU sees no boost pressure then its MAP sensor always sees ambient pressure so it is fundamentally completely in the dark about how much load the engine is under... Except throttle position for driver demand and of course the signal from the MAF about air mass entering the engine (but how useful is that if it goes FSD at half the amount the air actually being consumed).

WOuldn't you be better connecting the manifold pressure to the ECU so that the MAP sees whats going on - you can tweak the pressure map so it doesn't complain of 'excessive pressure' and use this as some possible way to catch failure situations if the boost controller goes crazy and provides higher boost than you permit in the pressure map. The WGFV map can just be ignored of course as the boost controller would be doing its thing (even though it has no idea about timing, fuelling and any potential knock).

[Rusty]

Yeah, sounds like Motronic is going to have a paddy about that one

[Jamo]

Uhhhhh - I don't get that bit... If the ECU sees no boost pressure then its MAP sensor always sees ambient pressure so it is fundamentally completely in the dark about how much load the engine is under... Except throttle position for driver demand and of course the signal from the MAF about air mass entering the engine (but how useful is that if it goes FSD at half the amount the air actually being consumed).

WOuldn't you be better connecting the manifold pressure to the ECU so that the MAP sees whats going on - you can tweak the pressure map so it doesn't complain of 'excessive pressure' and use this as some possible way to catch failure situations if the boost controller goes crazy and provides higher boost than you permit in the pressure map. The WGFV map can just be ignored of course as the boost controller would be doing its thing (even though it has no idea about timing, fuelling and any potential knock).

You've hit a nail on one point, ECU seeing excessive pressure, that's why it's has to be disconnected.

People using a boost controller wont have the ability to change the pressure map in the ECU, that would require a remap which is £XXX defeating the point of buying a boost controller.

[4WheelDrifter]

I had a crude MBC fitted to my S2 when I first got it, although the stock MAP sensor was still in use. The trouble is, if you have a running problem or fault with an engine sensor, the lack of boost can be the first sign of trouble. Without the ECU and the N75 controlling boost these faults could go unnoticed, increasing the risk of engine damage.

The ideal thing would be to have some sort of beefed up N75.

[Jamo]

The question was how to connect up a boost controller, if the ECU is no longer controlling boost it does not need to see a boost signal.

I agree on your points 4WD and in the big threads I've listed the pro and cons of both.

End of the day until you've driven an S2 with an electronic boost controller you can't appreciate how much better it is over the stock system. Boost rises quicker and boost is possible at part throttle, my major issue with the stock system only having 0.4 boost unless you have WOT sucks.

I'm going for a happy medium of 1.9 bar wastegate spring and ecu N75 to start with and then I'll play with my aftermarket boost controller.

[Rusty]

End of the day until you've driven an S2 with an electronic boost controller you can't appreciate how much better it is over the stock system. Boost rises quicker and boost is possible at part throttle, my major issue with the stock system only having 0.4 boost unless you have WOT sucks.

I've often seen over 0.4bar on partial throttle, what do you mean?

[Jamo]

The Motronic ECU is setup so that unless you are at WOT you cannot see maximum boost.

[HPmuirt]

End of the day until you've driven an S2 with an electronic boost controller you can't appreciate how much better it is over the stock system. Boost rises quicker and boost is possible at part throttle, my major issue with the stock system only having 0.4 boost unless you have WOT sucks.

I am sure it could be better, but it all sounds very messy compared to simply remapping the car to be what you want and using the standard controls, checks and balances. Also, why do you want more boost at part throttle? The car would be almost undriveable if you had massive boost at only light throttle openings

In terms of boost controllers, I prefer the bio-mechanical approach (or my right foot as most would call it ) which works like this: -

Some boost = push right foot down a bit
More boost = push right foot down more
MAX boost = mash right for down :mischeif:
Less boost = lift right foot up (Not often required, but I keep it as an available option)

Cheers n

Si

[Jamo]

As I said those who haven't driven a car with it don't really understand.

[4WheelDrifter]

I am sure it could be better, but it all sounds very messy compared to simply remapping the car to be what you want and using the standard controls, checks and balances. Also, why do you want more boost at part throttle? The car would be almost undriveable if you had massive boost at only light throttle openings

In terms of boost controllers, I prefer the bio-mechanical approach (or my right foot as most would call it ) which works like this: -

Some boost = push right foot down a bit
More boost = push right foot down more
MAX boost = mash right for down :mischeif:
Less boost = lift right foot up (Not often required, but I keep it as an available option)

My current daily driver will hit full boost at part throttle, and personally I don't like it. It can be tricky in the rain in the first couple of gears, when you try to put some medium effort in but the ECU has other ideas.
I'd rather take Si's approach to boost control.

[Rusty]

Drive by wire Stu?

[Jamo]

Fine by me, each to their own and all that!

[S2central.net]

Jamo - Its not like the ECU only generates boost at WOT - even in factory setup you will get much more than 0.4bar boost at part throttle. I dunno where that comment comes from.

All I'm saying is that if I was gonna use an aftermarket boost controller - to avoid entrusting boost control to N75 and the mighty ECU - I would keep the MAP connected and tweak the pressure map so the ECU doesn't cry foul... and allow some kind of safety feature.

IMO - if you go aftermarket boost control then you lose a lot of safety features built into the Motronic system... In order to retain some safety (not all aspects) then some knowledge of the Motronic is required.

Tell you what - if you let me know the MAX boost you want the ECU to see before it raises an alarm (should the boost controller fail and provide dangerous boost levels) then I can diddle you a turbo chip to suit. Its gonna need a 3bar MAP of course... And you should keep N75 connected (or simulated with a suitable resistor) so that the ECU doesn't raise a fault code on that.

The boost controller just gives more boost - thats all - its not equivalent to a remap or decent chip upgrade IMO. If you want to modify those parameters without Motronic knowledge then you need an aftermarket ECU as well.

IMVHO - boost controllers would be a worthy upgrade on the S2 if it weren't for the availability of decent chip upgrades that do the complete job with boost, fuel & timing tweaked in a failsafe environment. I'm referring to things like Homefries of course and chips and remaps from the likes of MRC and other worthy specialists.

On the S2, I would only look to the aftermarket boost controllers for applications where custom programming on an aftermarket ECU is in play - probably more likely on monster conversions for trackday / dragstrip specials and where the MAF is deleted etc etc and fundamentally where all of the Motronic safety stuff is much less important than on a daily driver out in all sorts of weather drinking all sorts of different fuel.

Just my humble opinion... but the offer for a hacked turbo chip on yours still stands if you are so determined to go that way