Factory in-dash boost gauge settings?

[PeepPaadam]

I got pretty much everything to work on 944 Turbo but struggling with factory in dash boost gauge. It seems to work with switched +12v but stepper output did only resulted the needle pegged and playing with settings either got it fluctuation between min and max or standing still in the middle and not responding toany pressure change.
Connected the pin to P259 ch0 (EC36 pin4) resulted the same thing but then I changed signal to inverted and it sort of started to reflect changes in pressure but obviously way off the scale and needle fluctuation like mad. The settings for this kind of behaviour were something like offsett 46 and multiplier 44.

Any ideas what to try next? Do I have to add some capacitors/resistors etc? Anyone has any working settings for ANY factory boost gauge?

The dash itself looks like this. Factory DME shows absolute pressure, meaning 2 bars on the gauge is actually 1 bar of boost pressure.

[gunni]

I would try a few fixed PWM values, you will probably find that the gauge works unlinearly.

i.e 50% is half way in the middle, but 60% PWM might be fully pegged.

[PeepPaadam]

Would scoping output from original factory ECU help?

We got the BMW economy gauge to work perfectly on E36 using tach circuitry: https://www.youtube.com/watch?v=uxyGXS3abi8

P.S. He is a talented guy, built a controller for the DCT trans and put that to his E36

[gunni]

More on the DCT setup?

What is the econo gauge doing? Representing Bar of boost? more info?

[PeepPaadam]

Economy gauge shows absolute pressure: 20 is 1 bar of boost. Getting it working required using 2nd E36 gauge cluster PCB and using its tach circuitry. 0 and 47 settings seem to work in VEMStune boost gauge setup for this.

Regarding DCT, it is from E92 M3, my friend Ivar made a controller board for it. Here's a bit of info and photos of it: http://foorum.turboclub.ee/viewtopic.php?f=5&t=4503&start=315

[PeepPaadam]

So, I dug a bit deeper regarding the 944 Turbo in-dash boost gauge and it appears that it is driven with just 0-4.5v voltage. 0.45v gives 1bar.

Here's some information about it and a guy got it working with external MAP sensor and some additional bits, but is there any way I could utilise VEMS internal MAP signal to feed the signal to boost gauge?
http://rennlist.com/forums/944-turbo-and-turbo-s-forum/434511-q-for-electronics-techs-boost-gauge-control-2.html

[VEMS]

Hello Peep,

We already have a function for that called boost gauge more info (although very limited) on: http://vems.hu/vt/help/v3/v3_tach_boostgauge.html; If you have some readings of what PWM percentage (or voltage level) you want at what boost level (3-4 boost levels preferred so i can plot slope/offset) i can take a look at the required settings.

Best regards, Dave

[PeepPaadam]

Boost gauge funtion with PWM does not work (needle is pegged or wiggling or does not repond at all), this was the first thing I tried, both stepper output and P259 output (we got BMW econo gauge working perfectly with P259 output though).

Porsche 944 Turbo boost gauge needs steady voltage output that ranges 0-4.5 volts. Just like MAP output. In original KLR ecu the MAP sensor output is sent to boost gauge through some resistors and .47uF cap. I would like to do the same with VEMS but so that 1 bar is 1 bar of boost not absolute.

[VEMS]

If the 944 Dash needs some steady voltage using a PWM controlled p259 output together with 1k-4.k7 pullup to 5v and a slow RC filter after that should produce that.

Best regards, Dave

[PeepPaadam]

Sorry for stupid question but what is RC filter?

[MWfire]

http://en.wikipedia.org/wiki/RC_circuit

[mc2226]

hi,

sorry for bringing this topic up.. but did you manage it to work?

i have some kind of the same problem.. but with an audi 100 c3 cluster with built in boost gauge.
i tried to solve it with a rc low pass filter but it didn't work (maybe it was soldered false?).

is there more info about how to install the rc filter right?

i know that in the motronic pnp ecu the boost gauge works.. how is it made?


thanks a lot!

bene

[steewax]

Hi Bene I also have a c3 cluster and try to get the boost gauge to work. Did you have any success so far ? Greetings Steve