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Matt - have you examined the MAP connections required? The GM MAPs all use three pins. I got a voltage table for the 4bar MAP I bought. Since I already have the ME7 IAT pre-TB, and the atmospheric pressure and ambient temp sensors, I reckon I should try this sooner rather than later . Esp with the 4" inlet piping....

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Matt - have you examined the MAP connections required? The GM MAPs all use three pins. I got a voltage table for the 4bar MAP I bought. Since I already have the ME7 IAT pre-TB, and the atmospheric pressure and ambient temp sensors, I reckon I should try this sooner rather than later . Esp with the 4" inlet piping....

Yes you will only need 3 pins, 5V, GND and Signal. Not sure what sensor im going to use yet and havent decided what IAT sensor I am going to use yet either.

Probably GM versions.

All that text was just theory, I dont really have any code yet, So it will probably be some time.

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edit:

I've added a FAQ page to the m44 wiki, clearing up some issues people are having / could be having. If anyone has any suggestions, feel free to express them.

More on that later though.

Looks good - your FAQ page :-)

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Those values are with the previous base FP of 3.9 (3.5 vacuum attached) bar. So you think even with the lower pressure I should retain the same values for now?

Aha OK, I thought these were values obtained after lowering the fuel pressure. My mistake :blink:

In that case, like my son allready said, you were right about the changing the injector constant and dead times ofcourse.

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Aha OK, I thought these were values obtained after lowering the fuel pressure. My mistake :blink:

In that case, like my son allready said, you were right about the changing the injector constant and dead times ofcourse.

I left the dead times for now, and just moved the constant.

WOT in 3rd 4th & 5th - if anything, a little rich, so I have room to play. NOT logging boost, so ignore that value

Wot3rdApr01_zps065059ab.png

Wot4thApr01_zps152b95f7.png

Wot5thApr01_zpsaa649c6c.png

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We did some measurements on the 3" ID audi A8 MAF, Lookforyou send us, with some rather surprising results.

We mounted the 3" audi A8 MAf, with a stock sensor installed, in front of the airbox and measured the output voltage with an arduino together with the outputvoltage of the stock maf which was in its normal position.

Before that we had a stock 850 MAF installed in the primary postion and a stock 850 MAF in the secundary postion to see if there was any offset due to the mountng position.

There was no offset, there was virtually no difference in outputvoltage over the whole 0 to 5 volt range between both stock 850 MAF's which made us conclude that our method was valid.

We expected a higher capacity with the 3" audi A8 maf as with the 2.75"ID S90 MAf, but this was not the case.

To be sure we did a second measurement with the S90 MAF as the primary maf and the audi maf as the secondary..... same results.

On closer inspection we noticed that the mounting flange for the sensor of the audi maf was 5 mm shorter and therefore the sensor went in deeper.

As a result the sensor filament in de S90 maf was more in the center then in the audi maf.

S90_audi%20maf.jpg

Closer to the wall the airflow is slower with a laminar airstream.

An explanation therefore could be that being closer to the wall in a audi A8 maf, the sensor filament cools down less.

If this is true then elongating the mounting flange of the audi maf should improve its measuring capacity...... that will be the next experiment we will conduct.

There are some myths regarding the MAF system.

One of them for sure is that the intake setup has an influence on the measurement of the maf... we found that this is absolutely not the case.

As long as the airstream through the maf is laminar and not turbulent (as it should be, otherwise the intake setup is designed wrongly anyhow) the maf has no knowledge of what's in front or after it.

It simply does what it should do, it just measures the amount of air which passes through the maf.

Whether there is an airbox in front of it or not, or it has a 3" or a 4' intake tube, with or without a 90 degree bend directely after or before it, it makes absolutely no difference,

We have tested it..

This makes dialing in a bigger maf a lot easier, once you have downloaded a valid maf table for your maf you are good to go.

Another probable myth maybe is that you loose to much "resolution" with a bigger MAF.

Not that I have noticed so far but more testing has to be done.

There is absolutely no difference in driveability and idling with my S90 maf installed instead of the stock 850 MAF.

I have not driven with the 3.25" maf yet though, I will do that shortly, but I suspect that the resolution of a maf is intrinsically high enough to go way bigger without noticing any effects of a lowered resolution.

But that's something I'am not 100% sure of yet.

I

Edited by Piet
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I left the dead times for now, and just moved the constant.

WOT in 3rd 4th & 5th - if anything, a little rich, so I have room to play. NOT logging boost, so ignore that value

Looking at your injector duty cycle you still have a lot of headroom, so it seems.

What is your highest injector duty cycle you've been seeing now?

Values aren't bad at all, in my opinion.

Maybe you could try lowering the injectorconstant another 2% to get even better values.

How is idling now, did it improve?

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Hussein, the logs are looking good! Couple of questions, why is your load lower at 7k RPM than at 6K? With the MAF voltage readings about the same, I can see them being the same, but not less at higher RPM. I noticed the battery voltage was kinda low too.

Piet, very nice on the test results. I also thought that intake design wouldn't matter to the readings.

Rod

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On closer inspection we noticed that the mounting flange for the sensor of the audi maf was 5 mm shorter and therefore the sensor went in deeper.

As a result the sensor filament in de S90 maf was more in the center then in the audi maf.

S90_audi%20maf.jpg

Closer to the wall the airflow is slower with a laminar airstream.

An explanation therefore could be that being closer to the wall in a audi A8 maf, the sensor filament cools down less.

If this is true then elongating the mounting flange of the audi maf should improve its measuring capacity...... that will be the next experiment we will conduct.

Im glad you found this. I bought a 3" ID housing from eBay, I noticed the sensor was off centre by about 5mm, I asked the seller about this as I thought the readings would be off. This is what he said.

The top is not centered so that would make sense. Nice photo. count the cells to the left and to the right they appear to be very close to equal on either side. and that is a rough visual positioning. Does the sensor need to be dead balls accurate, nope. If this were so we would not of been able to sell for the past 5 years.

If your not pleased with this maf housing please return to us with a copy of the purchase, and we will give a full refund. no worries.

So, If a 5mm shim/spacer was fitted between the housing and the sensor, it should bring it central.

Edited by Avinitlarge
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(I notiiced the lower battery voltage too, maybe an oxidized battery cable pole, a very common issue)

Not on my wagon.... :-)

Looking at your injector duty cycle you still have a lot of headroom, so it seems.

What is your highest injector duty cycle you've been seeing now?

Values aren't bad at all, in my opinion.

Maybe you could try lowering the injectorconstant another 2% to get even better values.

How is idling now, did it improve?

Highest duty so far is 67% - seen in the 3rd gear pull to 7600rom.

Idling has been better since I last redid the MAF table below 1.5V, adjusted the inj dead times slightly over the provided values and modified the 1st 4 RPM scale columns 360 / 810 / 1050 / 1290. No additional change with this regulated pressure adjustment.

Hussein, the logs are looking good! Couple of questions, why is your load lower at 7k RPM than at 6K? With the MAF voltage readings about the same, I can see them being the same, but not less at higher RPM. I noticed the battery voltage was kinda low too.

Rod

Once you go over peak load, the system pulls values from the next lower load rows - you can see this as the timing values also rise . Load is also gear dependant - for any given rpm the load will be higher as you go up the gears. This will also vary with the ratio of your gear set and final drive, of course. I don't see the kind of curve TMM9 posted in the linked thread.

My setup also has a very nice EBR of under 1:1, this also has an impact.

I don't know for sure that that would change with a different MAF table, load does decrease in the upper rpm's, even though HP does not :D . It will be interesting to log once I have a table for the 3.75" ID housing

10170759_10151931795191370_218847377_n_z

Voltage drops as rpm increases. Haven't seen anyone else log voltage @ 7-8K RPM - so I don't know if it's normal drop for these alternators at that rpm or not. You can see the progressive drop in the three screen shots as rpm rises. My alternator is a custom high output reverse rotation setup for my hybrid ancillary mounting with late style dual rib serpentine belt & tensioner

IMG_0228.jpg

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