(Strangest Question Ever?) Anybody got a Turbo Switch fitted?

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Ian you've really just made me laugh out loud. Thanks I needed that.

Answer:

Sell S3

Buy scooter

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I am the master at getting my MPG up to around 29 for about a day then for some reason the little voice in my head say BLAST IT!!!!
MPG = 21 if lucky /ubbthreads/images/graemlins/tongue.gif

If you want economy like som1 said buy a scooter /ubbthreads/images/graemlins/grin.gif

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1.89 bar - how's that work?

Have you replaced the map sensor then?

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Custom remap to alter the ECU limp mode and a selection of boost enhancing parts.

I think what feel is saying is that the stock map sensor only reads to 1.54 bar.But i think that fueling must be at 100% above 1.54 bar so it probably makes no difference.

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I think what feel is saying is that the stock map sensor only reads to 1.54 bar.But i think that fueling must be at 100% above 1.54 bar so it probably makes no difference.

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Not so, fuelling is within the acceptable range, and turning the boost from 1.6bar to 1.8 bar produces about 30lbft...

I think you understood me wrong david,i meant that because the map sensor cannot read more than 1.54 bar you will be fueling for 1.54 bar at 1.8bar ...but seeing as 1.54bar is probably 100% duty cycle it doesn't make any difference.

I hadn't thought about the fuelling (but as you credited me with more intelligence Ryan, maybe I shouldn't have said /ubbthreads/images/graemlins/wink.gif )

What I meant was, I don't see how the ECU would boost over 1.55 bar with the stock MAP sensor, as it can't measure how much boost it has made...

@David - are you saying that yours is mapped to request 1.8 bar and you have "boost enhancing mods" to re-scale the MAP? What mods (a resistor?) ?

Please, could you explain further?

The ECU is mapped to request high boost (i forget exactly what) and also programmed to move the ECU limp mode limit (which can occur from pressure overboost or air mass flow readings).

I'm using a combination of electronic and mechanical means to produce high peak boost during which the fuelling and EGTs remain well within the safe range as measured on the dyno.

There is a lot of theory about the workings of the 1.8T at different boost levels, but real world observations suggest that silly boost peaks can be run maintaining fuelling and mostly avoiding ECU limp mode due to overboost.

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I think you understood me wrong david,i meant that because the map sensor cannot read more than 1.54 bar you will be fueling for 1.54 bar at 1.8bar ...but seeing as 1.54bar is probably 100% duty cycle it doesn't make any difference.

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The MAP sensor reads 0-5v...not so much 0-1.54 bar.
Tha VAG Com can only read to approx 2540mb absolute...whereas if you actually log the MAP sensor voltage with an accurate, calibrated DVM - such as a Fluke - you will see that the MAP sensor reads way higher.
Limp mode on Davids car is reached at approx 2890mb absolute...when the voltage output of the MAP sensor reaches saturation point - around 4.9v dc.

You can massage this value 3 ways...

Raise the lipm mode trigger point in the ECU map so it triggers higher up...but you still can't go above 4.95 / 5v anyway.

Or use a zener diode to sink any additional voltage above the limp trigger point - say use a 4.7 v zener...and you avoid limp (but the MAP sensor doesn't realise you are still adding boost, and hence doesn't add more fuel)

Or you fit an electronic adjustable clamp that follows the corerect MAP signal right up the a user adjustable point 0.1v below limp trigger...and clamps it there, avoiding limp mode...again MAP sensor doesn't realise you are still adding boost, and hence doesn't add more fuel.


The best solution is the first...get the limp point raised in the ECU code...
The rest allow you to run higher boost without limp...but you have no ECU control of the fuelling...so you have to be absolutely certain the fuelling is up to it.

On David's car...it is.
I can assure you...


The injectors are running at approx 94-96% duty cycle at 6000RPM in 6th....but this is unrelated to high peak torque boost levels.
Ideal? No.
Desirable? No
Dangerous to the engine? Possibly...on an extended top speed run.

Running lean anywhere? No...lambda is OK at all high boost levels...this has been proven.


As for fuelling related to boost levels...if the software code is correctly written for very high boost applications, you can compensate that way. Believe me and David when we say, that S3 will run 330+ lb-ft / 1.8+ bar boost all day long safely.

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Not so, fuelling is within the acceptable range, and turning the boost from 1.6bar to 1.8 bar produces about 30lbft...

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...and does it with perfectly suitable lambda values (still slightly rich) and with inlet temperatures not much above 20 degrees when measured on the RR.

The benefits of having a good map, and superb intercooling.

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@David - are you saying that yours is mapped to request 1.8 bar and you have "boost enhancing mods" to re-scale the MAP? What mods (a resistor?) ?

Please, could you explain further?

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The S3 David now owns was mapped to request 'high' boost when running Optimax fuel with uprated intercooling and high flow cats / exhaust.


Using a standard N75 valve, air filter etc, the boost will be measured at approx 1.6 bar.
This is purely ECU control.

De-restricting the whole turbo pipework system / hoses, pressure pipe etc) and adding a 4" cold air feed to the airbox resulted in a slight gain in measured - and ECU controlled - boost..up to perhaps 1.65/1.67 bar.

Canging the N75 will add boost...but hit limp...as will chaging various other bits of hardware! /ubbthreads/images/graemlins/wink.gif
But, with standard N75, FPR etc...that car will run approx 1.6-1.65 bar every day...on correct ECU control, and NEVER hit limp mode...all the EGTs are fine, the lambda readings are fine and the injector cycle times are fine.

Add a different N75 and it gets a bit more touch and go on certain things as explained in a post a couple above this one.

The MAP sensor has not been re-scaled, a resistor fitted, clamp added, or anything else...it's as it left the factory.
And it just works...

Another popint of interest:

Davids S3 (formerly my S3) was mapped through ('through' as opposed to 'by') Star Performance...there is a long and strange story attached to where the code came from, and who wrote it...which I don't intend to go itno here...
But, the car has produced more boost than any other with an allegedly 'similar' set of maps fitted...

We don't really know why...but it does...it looks like the addition of many small modifications has finally paid off in the grand scheme of things.
Regardless of what the power / torque figures say...that is one seriously quick S3...and very aggressive in its delivery.

Sounds a bit like the trick jabba did on bill's ihi ibiza.

get some lighter shoes,

can you just run off boost using your foot


i hear ya about the road works pain in the rear