UrS4, no boost guage?

[simurs4]

Hey guys i recently purchased a urs4 a week or so ago, loving it drives great need to fix a couple little things to get it registered but should be alright. my question is about the boost guages in these things, i don't have a display setting on my dash to view boost or anything like that, is that wrong? mines an australian delivered s4 so i dunno if we never got the boost guages down here or not. would be nice to see what its boosting to so i know if everything is sweet or not i might have to fit an aftermarket gauge if mine doesn't have one :S.
cheers.

[prj]

There should be 6 display settings in the trip computer.
Which ones do you have then?

[simurs4]

i took a pic to make it easier
doesn't look like other s4 dashes iv seen on here :S

[veneto rs2]

i took a pic to make it easier
doesn't look like other s4 dashes iv seen on here :S

It seems like your board computer has been changed sometime in the car life.

L/100km it's the instantaneous consumption on the B4 chassis (S2/RS2).....

But it seems to me that your turbo pressure reader on the BC it's working thoug...
If it works then it's just a matter of inscription/letters on the BC panel= L/100km vs BAR.

If you read 1.0 when you turn the key on (and it seems to me that it does) and you have a reading up to 2.0/2.2 when driving...
Then your instrument it's working.

1.0 bar it's the natural pressure of the atmosphere air ,the rest it's pressure generated by the turbo.

hence 2.0/2.2bar means 1.0/1.2bar of positive pressure from the turbo wich should be about right for your AAN motor if stock.


Stefano

[simurs4]

thanks mate, makes sense. i took it for a spin before, sometimes when going WOT it would only read 1.7 and stay there even when the revs climb, while other times it would go all the way to 2.1 etc. would this indicate a sticking n75 valve? it wouldn't be something like a boost leak would it? as im not suffering from overboosting etc.

[prj]

Test for boost leaks.
With stock software, 2.1 is totally normal.

[UrS4boy]

thanks mate, makes sense. i took it for a spin before, sometimes when going WOT it would only read 1.7 and stay there even when the revs climb, while other times it would go all the way to 2.1 etc. would this indicate a sticking n75 valve? it wouldn't be something like a boost leak would it? as im not suffering from overboosting etc.

Looks like someone has installed an Audi 100 trip computer in your UrS4. I am amazed that the L/100 km spot actually reads out the boost, which by the way, is absolute pressure (i.e. 1.0 bar = 14.5 psi = almost atmospheric. Should read, say 0.3 to 0.6 Bar on idle. Maximum boost (during the ECU-controlled overboost period (foot hard to the floor) is about 2.2 (or 2.1 Bar) or about 1.1 Bar (16 psi) of boost over atmospheric. That is normal for a stock, non-chipped, UrS4.

You should change your user profile to add your country of origin since the system defaults you to being a Yank. (with the American flag).

[prj]

The computer rounds upwards.
Might even be a CEIL function, not just round.
Thus stating that a stock UrS4 will make 1.2 bar in overboost mode is incorrect...

Sorry to nag.

[UrS4boy]

The computer rounds upwards. Might even be a CEIL function, not just round. Thus stating that a stock UrS4 will make 1.2 bar in overboost mode is incorrect... Sorry to nag.

a) who are you "nagging", me or Stefano?
b) what do you think overboost is other than 2.1 or 2.2 Bar (Absolute)?

[prj]

I do not think, I know
I'll post a pic later.

Target boost is 1.03 bar in overboost mode on stock ECU.
It can overshoot a bit, but it is not 1.2.

[UrS4boy]

I do not think, I know I'll post a pic later.
Target boost is 1.03 bar in overboost mode on stock ECU.
It can overshoot a bit, but it is not 1.2.

I don't think so. Overboost was 2.15 bar (Absolute). Check out pages 8 (graph) and 9(the text) in this pdf:

[prj]

I don't think so. Overboost was 2.15 bar (Absolute). Check out pages 8 (graph) and 9(the text) in this pdf:

First of all, all of those lines are not measured on a dyno, they are just marketing data.
And I believe the cold hard numbers in my ECU any day over a magazine. The article also states, that boost depends on load, which it does not.

It's 1.03 bar target boost, period. Yes, it can overshoot for a very short moment, but not by much. In stock form, N75 duty is mapped very conservatively to minimize the effect.

My computer has also many times shown 2.5 bar, when actual MAP sensor output was 2.3.

[UrS4boy]

...It's 1.03 bar target boost, period. Yes, it can overshoot for a very short moment, but not by much. In stock form, N75 duty is mapped very conservatively to minimize the effect. My computer has also many times shown 2.5 bar, when actual MAP sensor output was 2.3.

Gee does 1.15-1.03 = 0.12 = "not by much"?

Did you know that if you are running a 3.0 Bar MAP, the OE boost gauge readings are all screwed up (since they were calibrated to a 2.5 Bar MAP)?

I know lots of people with UrS4's that saw 2.2 Bar on over boost in the stock instrument cluster/trip computer boost gauge.

[prj]

Gee does 1.15-1.03 = 0.12 = "not by much"?

It's not much indeed.

Did you know that if you are running a 3.0 Bar MAP, the OE boost gauge readings are all screwed up (since they were calibrated to a 2.5 Bar MAP)?

I actually know the exact voltage output of each of these MAP sensors. This question was not needed. It also goes the other way around - showing less than actual. 1.2x times less actually.

I know lots of people with UrS4's that saw 2.2 Bar on over boost in the stock instrument cluster/trip computer boost gauge.

As did I uphill in fifth gear.
My point is, that the stock instrument cluster reports higher values. Perhaps due to no averaging or ceiling the values.
If you take the MAP sensors voltage output, put it in a 5V ADC and log the values, then comparing them to the bosch datasheet, as I have done, you will see what I mean.

[UrS4boy]

...If you take the MAP sensors voltage output, put it in a 5V ADC and log the values, then comparing them to the bosch datasheet, as I have done, you will see what I mean.

When I generate new and interesting UrS data, I share with everyone. Have you shared your data?