air flow meter upgrade

[dicko]

I have a 1990 320i e30 and i want to bin the old plate air flow meter and replace with hot wire type has anyone any info no this

[liam012]

search for MAF conversion
lots of info in other threads
yes there is good gains
its quite pricey
unless hoshy comes up with something special.....?

[charlE30]

What about using megasquirt? you can ditch the AFM and have a mappable ECU about £270 ready built

http://cgi.ebay.co.uk/Megasquirt-MS-ECU ... dZViewItem

Quite a few people on here are using it

[chu346]

MAF conversion is about £700

Megasquirt is just a waste on a 320!

Why not just put in a different engine?

[Brianmoooore]

Why is the MAF conversion so expensive? They're both only a single output versus flow rate transducer.
Shouldn't be to difficult to hook up an engine with a flap meter and MAF in series, then log the two outputs at all different flow rates.
Should be simple enough then for some of you computer/electronics geniuses to produce an interface.

[chu346]

Should be simple enough then for some of you computer/electronics geniuses to produce an interface.

Surely that's a job for someone with your skills

[Brianmoooore]

Surely that's a job for someone with your skills

My electronics skills are 30 years out of date (just like the electronics onE30's, so I'm OK with them) and the computer I learnt on was programmed by cards with holes punched in them, and gave the answers back on a teleprinter.

[Finny]

You sound like one of my uni lecturers, he goes on about them cards and how the computer took up a whole floor of the uni!

My electronics is ok but not sure if i could do that to be honest

[Brianmoooore]

the computer took up a whole floor of the uni!

Ours took up a whole building!

[JazzMan]

This sounds like an intersting idea - its a shame i've alway been rubbish at component level electronics!

[Ant]

all that is required to add a MAF in place of the AFM is a signal conditioner, I have played with this in the past but felt there was no real market/need for it so put the whole project on the shelf, been there ever since.

the early M50 B20 non vanos uses a MAF with inbuilt signal conditioner BTW, if anyones tempted ? e32 750 uses two of the same units iirc

Hoshy is midway through a Pic based setup to solve the conditioner issues, watch this space..

[chu346]

What are you saying Ant?

Are you telling us that we could use a M50 B20 MAF? Would that be virtually plug and play? What about using two M50 B20 MAF's as one seems a little bit small for a 2.5 or a stroker engine. Or are you saying we could just use the electronincs from the M50 B20 MAF and put it in a M50 B25/B28 MAF or just custom piping?

Two M50 B20 MAF's with custom pipes sounds cool

And a dustbin size K&N

[Brianmoooore]

the early M50 B20 non vanos uses a MAF with inbuilt signal conditioner BTW, if anyones tempted ?

Tell me more! I've got one of these doing nothing, and I'd love to get rid of the flapmeter on the wife's 325 touring, 'cos it causes issues with the LPG conversion.

[Morat]

the computer took up a whole floor of the uni!

Ours took up a whole building!

Tehee, I'm a pretty hardcore geek (computer science degree, now an IT Manager) so I really enjoyed freaking out my Uncle who worked for ICL for 20 years by showing him the camera I bought for my GF for christmas. Its probably smaller than a pack of smokes in total volume and has a 1Gb SD card.
He went into shock and started gibbering about the ICL mainframe he used to "operate" when he worked at a university. It had 128k "Usable store" and that was apparently really something.

Time change..... only E30s go on forever!

Megasquirt is £270??? What sort of gains would I be looking at from that?

[JazzMan]

all that is required to add a MAF in place of the AFM is a signal conditioner, I have played with this in the past but felt there was no real market/need for it so put the whole project on the shelf, been there ever since.

the early M50 B20 non vanos uses a MAF with inbuilt signal conditioner BTW, if anyones tempted ? e32 750 uses two of the same units iirc

Hoshy is midway through a Pic based setup to solve the conditioner issues, watch this space..

Would those be a straight swap or do you mean there are still conditioner issues when using those?

[H35-IAN]

i also would like to here about the advantages of this mega squirt!! pleaase anyone.....

[hoshy]

Hi guys just found this thread. It's still go on my maf conversion. Had a bit of a hold up sourcing the pic I wanted but I've found a couple now from eBay. Work will being in the next couple of weeks again. If I recall correctly the issue I was working on last was why the output voltage differed from the sampled voltage - quite a fundamental issue

So, in short I'm still working on it. I'll post up when it goes in to testing on my car, I'm determined to see it through. But to be honest with you until I get my motor back in January it's a bit of a back burner project. So don't expect much this side of Christmas.

[hoshy]

Surely that's a job for someone with your skills

My electronics skills are 30 years out of date (just like the electronics onE30's, so I'm OK with them) and the computer I learnt on was programmed by cards with holes punched in them, and gave the answers back on a teleprinter.

To be honest Brian, if you're used to that kind of programming you're closer to what I'm doing than many of my fellow IT professional co-workers. This is "man" computing. None of that pansy-arse Microsoft dot.net crap

[gareth]

this would be a wonderful bit of kit to have, i'd love to bin the flappydoorpowersuckingtransducerofdoom!!! they've caused me headaches in a lot of my recent cars!!!

what are the differences in the voltage signals? are they simply an analogue output or something more complicated? i have a contact thorough work that may be able to design / manufacture this sort of thing for us....

[hoshy]

It's pretty simple to be honest.

AFM outputs 0-5v and has a little air intake temp sensor. round connector ones also output a static 0-5v signal for CO adjust - which is mechanical on others. The MAF I have for testing is a Bosch 0 281 002 180 - I believe these were common on Astras - again it outputs a 0-5v based on air passing through. these particular ones also have a intake temp thermistor which appears to read the same as the one on my 318i afm. the reason you need to do some trickery is the fact that the output voltage curves differ between the meters. So you need to create a map between the two. this is what I'll use the pic for. somehow I'll hook both meters up at the same time on the car, take a sample of the output across the rev(air flow) range and store it in a table. then disconnect the AFM, and have the PIC lookup the value the ecu expects for any given input voltage. i.e if the Afm puts out 0.18v at idle and the maf does 0.22v (figures not tested) then the code in the pic needs to say - hey, I've got an input of 0.22, what do I need to output. it looks up the value in the table and generates that using a DAC (filtered PWM currently). The intake temp sensors should just hook up without modification.

three issues:
After filtering the PWM - will it be able to respond fast enough to give the famed quick throttle response of other MAF conversion.

Is 8bit 8bit AD/DA, which means it's got a a resolution of 0.019volts, high enough. I'm sure there are ways to figure all of this mathmatically but I'm going to put something together and test it.

How much air can my MAF take. If it's from a 1.6 it may not have the head room for a 1.8

I've just paid the eBay guy for the PICs - yay

[gareth]

would any of the larger vauxhalls with the V6 have a suitable one? or could a thermistor be fitted to any other MAF?

i wonder if it's a PT100 platinum resistance thermometer
resistance/temperature values are standard so wouldn't need calibrating in each case so it would make sense for the manufacturer to use these.

http://www.searcheng.co.uk/selection/co ... /pt100.htm

http://rswww.com/cgi-bin/bv/rswww/searc ... cheID=ukie

[gooner1]

Tell me im not the only one who,s totally lost after trying to follow this post. .but love the way you blokes are getting into it.Reckon if you get together you,ll solve it in a week.Whatever it is.

[gareth]

[hoshy]

My multimeter tells me that my room is 26C, at this temp the afm reads 1.8k and the maf reads the same. looking at your table I don't think these are PT100s. nice info though.

As for other MAFs, you could use any 5v maf that fits the air pipes. temp sensor is a bonus but you could always dig the one out of your old AFM

[hoshy]

http://www.elecauto.com/mpower.htm

found that. seems some guys on the m3 are swapping in a MAF that's presumable close to the original afm output and then making it run right by modding the ecu tables. nice idea. so ant, how about it?

[DaveD]

Tell me im not the only one who,s totally lost after trying to follow this post. .but love the way you blokes are getting into it.Reckon if you get together you,ll solve it in a week.Whatever it is.

i totally agree

but had a look at that spanish site and they do something to a 92 520 as well

what, i dont know ..can you tell us???..and would it work in 6cylinder e30s

[Ant]

Lots of fun to be had there then, that MAf looks to be the E36 325 M50 type, again with an in built signal conditioner........

as long as the output is within the same range, the chip can be mapped to suit but its not exactly a 5 minute job peeps.

[Martinaston]

If you try to use one without the signal conditioner could use any MAF you
like and just change it to the right size tube and take the settings from
that ? To save the bother of trying to locate one from a similar sized
engine. (and the cost)

[hoshy]

that would be one of the smoothest maf conversions ever. bolt on the maf, run a 12v feed for the hotwire and swap the chip.

Martin, my method would be more suitable to using any 5v maf. the method above requires the chip to be programmed on a per maf basis, lots of work but a very cool reliable, easy to install and unobtrusive conversion.

[gareth]

that would be lovely wouldn't it!!!

i suspect mine (M30) might need a bigger MAF though... though i'm not sure what size the 24v ones are, there's probably a fair range still...

what sort of power gains are to be had from binning the AFM? probably quite a few bhp on a large engine...

[Martinaston]

I've just got one from a rover 220D for the shocking price of £5.
I haven't measured it yet but it's huge It's bigger than the 325 TB for sure.
I'll have a play with it later.

[DaveD]

bored at work and found this firm that produce a maf conversion kit in the states for the e30 325 $799. it seems to produce an extra 10 bhp on an m3

http://www.splitsec.com/

it might give you clever fellows some tips

[hoshy]

for those interested, I got some new PIC processors today - work can begin again tomorrow on the maf project.

[Dan318-is]

Hsoh, long time homie;

u still want me as a guinea pig for the prototype?

[hoshy]

Hey Dan. I sure do dude. I've scored a laptop from work also so that's gonna smooth things over a whole lot.

I was gonna come to Ace but I have music lessons on Mondays now so can't make it. Anyway - point is it would be good if you could take one of the MAFs and look at the possibilities of how to fit your AFM and a MAF together - temporary arrangement just to make a map of the two sensors vs. air flow. As of Wednesday I'll be away til July 17th so won't have done enough work to sort out a trial run before my holiday, but if we can arrange a weekend afterward that would be sweet as...


(sorry for bastardising the thread dudes )