You're right. I was mind-melding M5 and 540 et al. But my point was that the 96 has an incredibly low MAF crossection per claimed hp Jay
Some data about these MAF. 5.2 use the type 4 which is measuring up to 1080 kg/h ... should be OK for 400HP but probably not a lot more! I also thought about combining the signals from two smaller MAF to fed the Motronic and increase the mesurable flow range. Not a so big deal on an electronic point of view. But I have not checked yet what is the maximum flow that the Motronic can interpret. If the numerical saturation is close to these 1080 kg/h that would imply also some modifications in Motronic tables ... a huge difficult step IMO Image Unavailable, Please Login Image Unavailable, Please Login
Eric, It's quite doable. What the current motronic saturates at is of no concern, since that # (in kg/hr) is beyond what the motor can induct by a large margin. The key is to have the actual transfer curves of the specific MAF in the Ferrari, add a second one, read both in to a uP at say 1,000 samples/sec as simple voltage signals - convert back to Kg/Hr signal via the transfer function - add the signals together (L + R) - possibly perform some "magic" - then reverse the conversion back to a voltage via the transfer function - and output the voltage to the Motronic via an ADC and maybe a 1:1 buffer circuit. A bit of hardware, a bit of software for the uP, and a bit of PFM. Jim
It is my understanding that a MAF is "calibrateable"..... If so how big is the "adjustment window"? In other words, how hard would it be to calibrate a single MAF with a larger cross-sectional flow area to replace the existing 355 5.2 MAF? This I believe would be the ticket since the 5.2 motronic is already configured to work with a "single" MAF....... right?
So Technical............... From my laboratory in the castle east to the master bedroom where the vampires feast The ghouls all came from their humble abodes To get a jolt from my electrodes. They did the Maf They did the Monster Maf The Monster Maf It was a graveyard smash They did the Maf It caught on in a flash They did the Monster Maf
LOL that was sort of the intention when I started this thread...... I wondered if anyone would get it ...... would you expect anything less fron gothspeed ??? Laudatory rites to bushwacker!!!
You don't calibrate the MAF, you calibrate the DME itself with a new MAF transfer function and reflash the calibration. done. Where are you going to find a MAF larger - that you have access to the transfer function - and you have to rework all the plumbing.
For starters.... that is why I started the thread... to find out: 1. Who knew what on the current 5.2 MAF configuration. 2. What kind of voltage signal the 5.2 MAF is sending?... modulated (if so at what freq. range) or linear 0-5 volts etc. 3. What is needed to use a larger MAF. So you are saying there is a "transfer function" involved.... great !! Could you delineate on how this is done or what is involved? The plumbing is/was not one of my concerns...... any help on the above though is very apreciated.
It's the same as any Mid 90's BMW "non-M" V8. Single Meter, 0-5v out. a) A larger MAF b) The transfer function or curve for same - equating this volts to that kg/h with 256 points of data c) a method to program same into M5.2 ECU. However - again let me suggest an alternative that does NOT require any ECU reprogramming. Since the BMW meter is preeminently "cheap" (compared to F parts) you buy two of those, adapt plumbing for "dual" meters ala 1995, and use a small independent signal convertor to combine two MAF signals into one. Two new meters, two new airboxes, a wiring harness adapter with a built-in signal convertor, and some plumbing. done. It's a LOT easier FWIW than trying to get the transfer curve for another meter - which Bosch is VERY stingy with. Jim
Cool! I was under the impression that using two of the one MAF already there was harder . I actually like the dual MAF idea better So as long as the two MAF signals are combined so that the output voltage is 'stacked' so to speak.... ? ..........or is there a way to run the two MAF voltage ouputs in "series" since each will be seeing only half the air hence half the voltage output would be coming out of each.... right? Thanks for the good info !
Because the MAF "airflow to voltage" function is not linear, you can't simply add the voltages. You have to convert the voltages back to airflow - add the airflows and then convert this new airflow # back to voltage. Easily done at least 1000 times per second by a tiny little microprocessor.
Wow! ok so the quest will continue for such a device...... I have also heard of people only hooking up one of the two identical MAFs to the ECU then using some HKS processor to double the voltage of it. As you have already guessed both MAFs are in parrallel to the air-flow in this arrangement. Have you heard of such a setup???
No, I'll make such a device. You can't "double" the voltage because the transfer function is not linear. 2 x the voltage DOES NOT EQUAL 2 x the airflow. Oh, were it that simple
Jim, I agree that this approach is the most efficient for a DIY solution. Reprogramming the ECU with a larger MAF would be a cleaner solution but much more difficult to implement because I think it is too risky to try any 5.2 look-up tables modification ... except for you !!! Two 2.7 airbox for straight plumbing, two 5.2 MAF or smaller with the cal curves (hot film type), 1 signal combiner/converter (a single PIC microcontroller can do the job) and that's it. The question is : Does it worth to do such a modification? Are the MAF, and the 5.2 plumbing, a real limitation?
I guess you could call it that (ewwww). The transfer curve is the graphed shape of the output voltage. In this case, the MAF outputs from 1 volt to 5 volts...based upon how much air is flowing past. But the curve isn't linear. An extra mole of air passing through the MAF doesn't mean an extra volt being output from the MAF to the ecu. To your "resolution" point, yes...the MAF outputs progressively higher voltages as more air passes through it, but this effect is even more pronounced when there are lower amounts of air. But, does Motronic 5.2 ignore the MAF output voltage at Wide Open Throttle? One wonders, if so, if the better solution for the DIY'er would be an intake cut-out...similar to an exhaust cut-out that by-passes the cat/muffler, except that bypasses the MAF when at WOT. In that case you'd have no electronic mods. You'd use the stock MAF and stock MAF output (transfer curve) voltage for idle and mid-range throttle, but bypass the MAF with a mechanical intake air cut-out for WOT. You could even use an electric cut-out device wired to a button on the steering wheel, throttle pedal (e.g. activated when foot hits floor), or on the stickshift (e.g. Mad Max's police interceptor) to trigger the intake air cut-out. This would be very effective, cheap, easy to reverse if selling the car, and would pass emissions because the OEM emissions equip would still be functional on the car.
No Motronic ever equipped w/ a MAF **ever** ignores the MAF under any normal operating condition. This is a misconception from some old Bosch L-Jet literature. Jim
5.2 MAF (0 280 217 800) are available there at a good price : http://stores.ebay.fr/goldstar-international I bought one. 2 others are available. I will probably try the 2 MAF configuration, with minimal plumbing mod in a first time, during summer. I have already started to look at the design of the signal combiner (based on a PIC microcontroler including the A/D converter). Software will come right after.
Good to know ! Sounds fabulous!!! Keep us posted on your progress !! BTW where would one find the 'extra' connector?
