MAFless tunes

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Rick

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	MAFless tunes « on: October 18, 2010, 01:03:24 PM »

Has anyone had a go?

Rick


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elRey

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	Re: MAFless tunes « Reply #1 on: October 18, 2010, 02:16:50 PM »

Would this just involve disabling any MAF error codes and disconnecting the sensor?


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RaraK

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	Re: MAFless tunes « Reply #2 on: October 19, 2010, 06:11:30 AM »

Quote from: elRey on October 18, 2010, 02:16:50 PM

Would this just involve disabling any MAF error codes and disconnecting the sensor?

thats what im assuming, however, do you still require a "scaled maf" to your injector size


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spen

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	Re: MAFless tunes « Reply #3 on: October 20, 2010, 03:09:25 PM »

no, there is more to it. Even if you patch up the DTCs so no error code is detected, you'll still generate an error in the ESP if you have it.

When the ESP drops dead, so does ABS and the brake bias goes 50% front 50% rear. Altogether not predictable

A famous tuner found this out when he stamped on the middle pedal at 160 mph and the car went through 520 degrees rotation after the rears locked up.

My belief is that the CAN bus carries LOAD as derived from the airflow to the ESP. When you use 'secondary load value' derived from MAP it is not transmitted over the CAN bus. To fix this you need a way of putting the secondary load on the CAN bus, and to do that is a structural change to ME7. Or a fudge would be to nail the CAN load signal at some 'reasonable' level. Not impossible, but certainly in the hard category.


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Rick

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	Re: MAFless tunes « Reply #4 on: October 22, 2010, 11:45:48 AM »

Spen,

what happens if the ESP is disabled in the ECU? I presume i'm going to have to do this with my new G/H box as my pre can S4 doesn't have it.

Still haven't got an ECU so haven't been able to "tune" anything...

Rick


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spen

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	Re: MAFless tunes « Reply #5 on: November 16, 2010, 03:16:29 AM »

that would depend on the reaction of your abs euc. On mine the esp / abs goes offline if the engine ecu drops on to aux load signal as happens when you unplug the maf.

try it. No maf = a 50-50 front rear brake bias on mine; which can be interesting. Without ESP I don't know what the reaction is.


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Rick

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	Re: MAFless tunes « Reply #6 on: November 16, 2010, 08:49:27 AM »

Will try it. Be so nice to get rid of all that piping!


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Rick

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	Re: MAFless tunes « Reply #7 on: November 17, 2010, 04:01:43 PM »

I've been doing a little more research into this.

I've been trying to see if there is a way for ME7 to use speed density for it's primary load calculation. The good news is that it is - the bad news is that we have no way of setting it. It is set by a system constant when the code is compiled. The system constants allow for fundamental changes in the way the code works. For example, you could change the number of teeth on the trigger wheel, number of cylinders, firing order etc. Unfortunately we don't have access to the ME7 source (if only!) so we have to make do with editing the hex file which has hard coded system constants.

The only option now is to force the ecu into its secondary load calculation mode, and then work around the limitations that this evokes.

Rick


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spen

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	Re: MAFless tunes « Reply #8 on: November 23, 2010, 05:05:09 AM »

we do have other options, but it would involve redirecting a function and writing something in assembler. We know where the check MAF voltage and conversion to an airflow happens. We can see the inputs and outputs of that function. if we jmp from that before any DTC check or diagnosis check we can create all the primary airflow and primary load variables using the secondary load value.

i quite like my MAF though. So much I'm going to add another MAF and straighten my intake that way. I intend to send an average signal to the ecu (with a drop dead if one MAF fails) and scale it in the ecu.


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Rick

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	Re: MAFless tunes « Reply #9 on: November 23, 2010, 12:42:13 PM »

i like mafs too - but not all that intake plumbing! Twin maf's would be very cool. I did think of relocating the maf on one of the compressor inlets and then just doubling the airflow for a given voltage - not as clever as your method though...

Rick


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blundar

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	Re: MAFless tunes « Reply #10 on: November 24, 2010, 07:20:59 PM »

These MAFs read in voltage (As opposed to frequency) right?

If that's the case, you could probably switch to a 2005-2010 Ford Mustang "slot style" Hitachi MAF. Specifically, the PMAS HPX (aka SCT BA5000) meter kicks all sorts of butt. These MAFs read very reliably in a blow-through setup so you can move them to a nice straight piece of pipe before the throttle body. Opens door up to venting bypass/diverter valves to atmosphere without weirdness. Super clean signal, even blow through. If you scale the voltage output, you can meter about 600-700hp of air from a scaled HPX (aftermarket scaling) meter in a 3" pipe blow through. I've used them on several Nissans (SR20DET, RB25, RB26) along with countless Fords (duh) with great success. I've metered 1100whp worth of air and had acceptable idle area resolution on a 5L modular V8 with a voltage scaled HPX meter in a 4" pipe blow through.

Some links from google with pictures:
http://www.themustangshop.ca/product/1479825/300435
http://www.themustangshop.ca/product/1479798/


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Tony@NefMoto

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2001.5 Audi S4 Stage 3

	Re: MAFless tunes « Reply #11 on: November 25, 2010, 03:03:07 PM »

I know some tuners are now using the PRO-M meters in high horse power Audis.

http://www.promracing.com/mass-air-meters-c-2/pro80-p-5


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Rick

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	Re: MAFless tunes « Reply #12 on: November 25, 2010, 04:16:25 PM »

I've never had an issue with the standard units. The problem is all the pipework associated with a twin turbo v engine.

Rick


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