Boost Controllers

[audiman]

I need to read this thro again. Lots of very good points here. Lambda can be turned off in the ECU, but like Graham said, you dont build a high BHP car to drive to the shops and do 35mpg. But having said that, my 480bhp car will do 27mpg if i sit at 75mph on the motorway. (Lambda active). Thats not bad IMO.

[audiman]

Damn i came in too late for the fight!!! Bloody hell! Always read the first page of a thread. Wish i did first. I can see the benefits, but i have to agree with others, i dont see the benefit on MY car. I have no problems with wastegate creep. And boost can be controlled just fine. I DO LIKE the low boost function, but would this dump excess fuel into the bores and wash them?? At the moment i remove the WG spring if it has to go anywhere. Not much fun with seperate WG pipe as it stays open! and is loud.

[steve930]

as far as i'm aware, boost controllers can't reduce boost levels below that of the standard wastegate or actuator setting, so i don't think you'd be any better off Tom.

I'm having this very problem in red shed2 at the min!!

[BRY]

as far as i'm aware, boost controllers can't reduce boost levels below that of the standard wastegate or actuator setting, so i don't think you'd be any better off Tom.

I'm having this very problem in red shed2 at the min!!

Have you read the first bit of this post?
Graham reckons that's exactly what it does !

[steve930]

Have you read the first bit of this post?
Graham reckons that's exactly what it does !

yes i have, and i also own the same controller as him, and it clearly states in the instuction booklet that you CANNOT REDUCE BOOST LEVELS BELOW THE CAR'S FACTORY SETTINGS

[BRY]

I'm off to borrow Jamo's Handbag to sort this out

[steve930]

as well as the greddy unit, as fitted to my skyline, i have also used the blitz dual sbc spec R, HKS evc4 & 5 controllers and you couldn't reduce boost levels below factory levels either

[steve930]

I'm off to borrow Jamo's Handbag to sort this out

[Rusty]

I can understand that this is the case with an actuator because it's a mechanical device that cannot be controlled by an electronic box. Would a boost controller be able to actuate the WGFV on the S2 (or is that what it does by messing with the MAP sensor in the ECU? If not then what we need then is the ability to control the WGFV and therefore boost. Maybe a dial that goes to 11 would be somewhere to start? When driving along normally it could be at 10 but when you need a little extra juice you can get it! (sorry, just been watching the immortal Spinal Tap!).

[rotoryboy]

Would a boost controller be able to actuate the WGFV on the S2

It comes with it's own replacement WGFV as part of the package/system

[4WheelDrifter]

So if there is a engine fault and the car goes into limp home mode, how does the ecu limit boost?

[Rusty]

It comes with it's own replacement WGFV as part of the package/system

In which case it can control the boost in the same way that the WGFV does, only with user control as to how much. Thinking about things a little more, the MAP must be able to cope with varying intake pressures and adjust all parameters to the reduced or increased boost as ABYs etc. have variable boost over the rev range and also overboost which are controlled by the WGFV. If the boost cannot exceed the factory or indeed modified waste gate spring then that provides a fail safe, which is the upper limit. Therefore, the controller must be able to allow boost from zero to the limit set by the wastegate spring providing. Just my tuppence... the debate continues.

[Rusty]

So if there is a engine fault and the car goes into limp home mode, how does the ecu limit boost?

At a guess, the WGFV does not allow WG to divert exhaust gas through the turbo to spool it up.

[Jamo]

I'm off to borrow Jamo's Handbag to sort this out

Sod off and get your own!

[tekkno435]

it can control the boost in the same way that the WGFV does, only with user control as to how much

Spot on. Technology has moved on in ten or so years and the boost controllers today are very sophisticated bits of kit, able to do far more than our WGFV's

If the boost cannot exceed the factory or indeed modified waste gate spring then that provides a fail safe, which is the upper limit. Therefore, the controller must be able to allow boost from zero to the limit set by the wastegate spring

Again, quite correct, are you sure you don't have one of these already? You can also tell at a glance what your peak boost has been, not a feature of motronic ecu's IIRC. The Apexi controller is also adjustable to the degree that you can have different levels of boost in different gears, also not a known feature of Motronic ecu's.
I am not suggesting that everyone rushes out and buys one but what i am saying is that this is a useful device and a real alternative to the stock setup. It also has twiddly knobs and flashing lights for those who like shiny toys:-) The S2 is, as has already been pointed out, fitted with a boost controller from stock. Audi choose to call this the Wastegate Frequency Valve, they cost how much to replace? £80.00 'ish? Well for another £100 or so you can get your own model in the guise of the Greddy controller i am presently using or a bit more gets you the Apexi. This is a no brainer for someone who likes to modify anything, which is about 90% of this forum.
The boost controller itself replaces in it's entirety the boost connection to the ECU and there is no longer a feed to the standard MAP sensor which the boost controller replaces. You are going to get better definition in any event as the Greddy unit comes with a 4 bar MAP sensor, so if you were thinking about replacing the stock MAP sensor with one from an RS2 for example, there is no need, the boost controller has one installed which is superior to them both.
If i indicated that this boost controller (the Greddy) was able to turn the boost off i unreservedly apologise, that is not what i meant. What i believe i said was that you can turn the boost off to the degree that the maximum attainable is that of the stock wastegate spring, in the case of the S2 this is 0.4 bar i believe.

graham.