How to calculate boost pressure by MAF gs / rpm and Lambda?

**mmartin191** · 28th March, 2020, 07:02 PM

Hi, does anyone know how to work out the boost pressure by Maf / Rpm and Lambda.

1.9tdi pd105
Diesel 14.7
Each cylinder is 474cc x 4
Atmos pressure is 1040

An example set of known data.
AFR: 11.44
Boost: 1990 mbar
MAF: 500
IQ: 29.73

I need to work out how the calculation for boost using the above.

Thank you

**DiegoStud** · 28th March, 2020, 07:28 PM

IQ 2973?- not likely... Patm 1040-rainy day where you are..... lambda 11.44- what even is this 11.44:1 AFR? Petrol? But 474cc is a 1.9TDI?.........wait you managed to run a TDI on petrol??

Edit: My bad 1040 is cracking the flags.

**mmartin191** · 28th March, 2020, 07:33 PM

I've made amendments to the original.
Injection quantity in MG is 29.73 (sorry read it without a factor applied.)
11.44:1 AFR
Diesel - 14.7

Edit -
This is the stock map of the car.

**DiegoStud** · 28th March, 2020, 07:47 PM

Stock map- EGR on-low MAF readings and rich lambda.
If you know the lambda you want this would help. Divide airmass by IQ and away you go.

**davorsule** · 28th March, 2020, 08:01 PM

Originally Posted by DiegoStud

Stock map- EGR on-low MAF readings and rich lambda.
If you know the lambda you want this would help. Divide airmass by IQ and away you go.

I think it's enough accurate for iq_limit_by maf map, turbo pressure> dividing 474 mg/stroke of air by maf value and got the pressure, and with pressure and AFR calculate iq_smoke limit.

**mmartin191** · 28th March, 2020, 08:04 PM

Sorry, it's stock in the sense of the maps previously mentioned, but egr is off etc.

**davorsule** · 28th March, 2020, 08:05 PM

Also this maf value=500 is with egr on, so you can't use this values. also afr is not good!

**davorsule** · 28th March, 2020, 08:05 PM

Originally Posted by mmartin191

Sorry, it's stock in the sense of the maps previously mentioned, but egr is off etc.

how you got these values?
with VCDS?

**mmartin191** · 28th March, 2020, 08:13 PM

This is from Winols. You're right though, I need to add the EGR values onto the maf.

**davorsule** · 28th March, 2020, 08:18 PM

Originally Posted by mmartin191

This is from Winols. You're right though, I need to add the EGR values onto the maf.

.. please see carefully are these values from stock maps if you look in winols?!
and explain what are you trying to do?
calculate max turbo pressure for which map or calculation?

**davorsule** · 28th March, 2020, 08:23 PM

For example I log data with VCDS while testing engine:
rpm=2331 rpm
iq limite=55,2 mg/stroke
duration=24 deg.
smoke limit=332 Nm
maf=1035 mg
turbo pressure=2173 mbar or 1,276 bar
atm pressure=897 mbar

**mmartin191** · 28th March, 2020, 08:23 PM

Yes these are completely stock values.

I have worked out the Injection quantity needed to achieve a certain AFR, I now need to work out how much boost is needed to correlate with that.

This is for the boost map.

**davorsule** · 28th March, 2020, 08:29 PM

Originally Posted by mmartin191

Yes these are completely stock values.

I have worked out the Injection quantity needed to achieve a certain AFR, I now need to work out how much boost is needed to correlate with that.

This is for the boost map.

yes, I understand, and what is your maximum maf value and iq?