I have come up with a cunning plan to plot the output curve of the S2 / RS2 MAF...
Why - cos it is completely undocumented in the public domain. I have politely asked a number or Bosch agents for datasheets but even they don't have them to divulge. Quite why Bosch is so protective about 20yr old technology I dunno.
ANyway - here is the plan... Fortunately there is a range of Bosch hot FILM based MAFs which do have documented data in terms of an output voltage for given mass of air intake (grams per second for example).
The plan is to buy such a hotfilm MAF and bolt it up in front of the (R)S2 MAF and hook up both MAF outputs into an ADC. Then simply take the car for a wee drive and I'll be able to plot the RS2 MAF characteristic by correlation against the hot film reference MAF.
This is the only viable way forward as I haven't been able to locate anyone with a flowbench capable of such throughput - then I figured I can use my car as a flowbench !
So onto the question of ADCs then - anybody got any experience of something like this -
Its a UK firm who make an award warning PC based oscilloscope for lots of money - they look clued in and their ADC seems to have the right capability for my needs. 20kHz is plenty fast enough sample rate and it offers lots more channels for growth into other test scenarios.
Once I have this data we will then have some means of being able to pinpoint MAFs which are in/out of spec. I'm using a fresh RS2 MAF here, but will happily test as many MAFs I can get hold of for more diligence.
I'll have to cough up for one of these Bosch hotfilm jobbies - there is at least one with 80mm form factor - all I need is some ugly tubing to link them both together - and get the airbox out of the way. ECU will run of normal MAF for driving of course.
The eventual upside of this is being able to unlock the MAF scaling secrets in the ECU so that we use bigger / better MAFs than the stock item. That has three main benefits :
1. Better dynamic range as the factory one maxes out quite early. Its over 2V at idle already - duhhh
2. Less restrictive intakes on big upgraded engine with a means of putting RS2 MAF internals into a bigger tube for example.
3. More reliability with the possibility of migrating from precarious hotwire to more robust hotfilm technology... negating the need for hotside MAF locations and/or going to aftermarket ECU
I think the MAF scaling stuff will hurt my head for a long time - that is the eventual goal, but for a little spend there should be some easy wins in the short term.
Any other suggestion on good ADC with USB connection under £200 ?
Ta,
Paul
Why - cos it is completely undocumented in the public domain. I have politely asked a number or Bosch agents for datasheets but even they don't have them to divulge. Quite why Bosch is so protective about 20yr old technology I dunno.
ANyway - here is the plan... Fortunately there is a range of Bosch hot FILM based MAFs which do have documented data in terms of an output voltage for given mass of air intake (grams per second for example).
The plan is to buy such a hotfilm MAF and bolt it up in front of the (R)S2 MAF and hook up both MAF outputs into an ADC. Then simply take the car for a wee drive and I'll be able to plot the RS2 MAF characteristic by correlation against the hot film reference MAF.
This is the only viable way forward as I haven't been able to locate anyone with a flowbench capable of such throughput - then I figured I can use my car as a flowbench !
So onto the question of ADCs then - anybody got any experience of something like this -
Its a UK firm who make an award warning PC based oscilloscope for lots of money - they look clued in and their ADC seems to have the right capability for my needs. 20kHz is plenty fast enough sample rate and it offers lots more channels for growth into other test scenarios.
Once I have this data we will then have some means of being able to pinpoint MAFs which are in/out of spec. I'm using a fresh RS2 MAF here, but will happily test as many MAFs I can get hold of for more diligence.
I'll have to cough up for one of these Bosch hotfilm jobbies - there is at least one with 80mm form factor - all I need is some ugly tubing to link them both together - and get the airbox out of the way. ECU will run of normal MAF for driving of course.
The eventual upside of this is being able to unlock the MAF scaling secrets in the ECU so that we use bigger / better MAFs than the stock item. That has three main benefits :
1. Better dynamic range as the factory one maxes out quite early. Its over 2V at idle already - duhhh
2. Less restrictive intakes on big upgraded engine with a means of putting RS2 MAF internals into a bigger tube for example.
3. More reliability with the possibility of migrating from precarious hotwire to more robust hotfilm technology... negating the need for hotside MAF locations and/or going to aftermarket ECU
I think the MAF scaling stuff will hurt my head for a long time - that is the eventual goal, but for a little spend there should be some easy wins in the short term.
Any other suggestion on good ADC with USB connection under £200 ?
Ta,
Paul
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