Rogue_Ant

Do you have any logs?


-Rogue

RajDatta

I have dyno pulls on paper.

Rogue_Ant

Can you post it?
What chip setup did you use?


-Rogue

RajDatta

Rogue, I don't have a scanner. The chipsets were used to initially get the maf to work and from there on we had the car dyno-tuned and new chips were burnt. They used 100 rpm increments to tune the car. Max boost was 15.3psi. Car made 360lb/ft of torque at 5000rpm with max of 348hp to the rear wheels on a Dynapack Dyno. These were SAE corrected numbers in 90 degree temps. His Dyno is extremely conservative, as much as 10-12% compared to a Dynojet.
Regards.
Raj

JohnKoaWood

I never said it couldn't support a higher HP motor, I said it maxes out...

The Scivision MAF is a good kit for the lightly modified car...

BUT the Bosch sensor being used MAXES out at 1084 CFM... or roughly 6000 RPM at 20 PSI on your 3L motor... with calibration of the controller for the SCIVISION MAF you have a lower V out threshold...

I bet your MAF, assuming you are using the 951 Scivision MAF and controller, are maxed out, but your tuner got around the lack of rise in MAF response with fuel control in your MAP...

I further assert your MAF V out was maxed at below 4000 RPM WOT during tuning..this is a band-aid at best... and you can and will realize at some point the limit imposed with running this setup... now if you were to swap out to a larger flowing MAF sensor (like a Bosch HFM7 or even a HFM6 for that matter) you would see a slower rise and need to retune your MAPS, but would gain better mid throttle fuel management (up to 79% throttle anyway)..

but I only know a little bit about these things... do you have a monitor on your MAF V out to the DME?

I do, and my MAF V out is maxing out (4.8V seen at 5200RPM WOT)... I also manage this with the fuel map, but will be going to stand alone EMS when I upgrade this winter... I'm planning on playing with SD tuning rather than a MAF, but still might USE a MAF to get going, just not my current one....

building a DIY MAF isn't impossible, nor is it beyond the skill set of many on here, but for the average bear on here, many of which use their car as their only mode of transportation it isn't a very good idea.... if you want a MAF buy a kit... or be ready to play with more than you think you will need to...

Rogue_Ant

Some misconceptions on how the DME works.

Here is the basics:

The DME uses the AFM input at all times, period. That means idle, part-throttle and WOT.
The DME has no true TPS input. The only direct TPS input is the idle switch. The TPS angle goes to the KLR. Whenever the TPS value is >60%, the KLR sends a signal to the DME telling the DME to go to the WOT fuel/timing tables.

The stock AFM maxxes out around 4.6-4.7volts. The DME, however, doesn't max out until it receives ~5.0v. The Scivision MAF will output a full 5v to the DME, thus the higher HP limit compared to the AFM.


-Rogue

333pg333

Quick OT Raj, do you have a thread re your build? I'm interested in what you've found with the GT3076r? This is on a 3L 8v motor? I have one on my current 2.5L 8v and I am very impressed. I would think that on a 3L motor it must be very quick to spool if not a little small for that application. I'd like to read some of your feedback.

Back to interesting thread.

tommye

Hi,
I recall reading somewhere that at WOT the AFM input is ignored and the DME basically uses only the rpm input.
Can you elaborate on this ?
Thanks,
Tommy

Rogue_Ant

Sure,
The DME uses the AFM input, along with AIT and baro to derive mass airflow. Once the DME knows airflow mass, it calculates base injector pulse width to achieve a 14.5:1 AFR. This calculated value then gets modified by idle/part-throttle/WOT maps (among other things).

The misconception about the AFM input being ignored at WOT is due to not fully understanding how the DME works. The WOT fuel table, like the idle table, is a 2D table. This tables only axis is RPM, and is why I believe people are confused.



At first glance it appears that there is no AFM input. However, this is not the case at all. The maps are only modifiers. They modify the base injector pulse width calculation. The DME has already calculated this base number from the inputs mentioned earlier (AFM, AIT, Baro, RPM, ect).

For proper fueling, the AFM input is always used. Timing is a little different story though. When in the idle or WOT tables, the AFM input is not an axis. In these cases, timing is completely based off of RPM.




-Rogue

tommye

Ok, I think I understand better now - at WOT and above 5000 rpm or so the AFM will max out giving almost the same output regardless of rpm. Here the rpm will practically work as the only input while the static AFM signal will only indicate that there is flow.
Cheers,
Tommy

DANNiE

well some really good and interesting ideas being tossed around in this thread... I thought id chime in on MAF's since it seems to be what all the talk is about...

I read in many posts the use of the Mustang Cobra MAF the only purpose of using that MAF is the actual Dimension the actual bore size is just about as large as a MAF can get...

So in all reality the hassle of mating a Ford MAF to the car is peanuts... Its like in my VW tuning days where people swear by having a throttle body bored out it makes these huge power gains...

The reality is that the motor in our cars is a maximum size of 3.2L for the Four banger and a 4.6L Ford Cobra MAF in relation to CFM intake via displacement is really just over kill and seemingly more than might be needed...

Another point to bring out is that a MAF sensor as one person describes it earlier in the post is perfect as he tells what the difference is between the "FLAP DOOR" Air type sensor and a MAF meter Key words are Meter and Sensor... Keep that in mind...

One other tip I found from working at the VW and Audi dealerships is that on 2L ABA motors and 1.8T AEB motors the MAF meter is the exact same part number..! So N/A or Turbo use the same MAF... -srugs-

So all in all hunt for peanuts...

The best advice ive seen on this Thread is Get the Megasquirt and use a MAF or MAP sensor and call it a day...

Just my thoughts on this one...

barks944

I have been working on this very problem myself. I have built a USB programmble device with the facility to calculate the signal sent to the DME based on the air mass signal from the MAF and the air temp sensor. This allows for temperature compensation of the MAF sensor to correctly output air flow to the DME. The device cost <£50 to build ($100?) and when I am done I will probably release the source code for it.

It is built around an arduino Nano prototyping board which is available for circa £20 here in the UK, the MAF and additional components cost me less than £30. The programming language is C based and you load the program onto the chip via USB, the chip has analogue inputs, PWM and digital I/O. The only major addition was that of a DAC and an opamp to generate an output 0-5v signal to the DME. This circuit is easily buildable by anyone with basic soldering skills and some time and patience. Most of the complex circuitry is already built into the arduino chip.

I am currently setting up the conversion from MAF to AFM. This is a little difficult due to a lack of information on the MAF but I have made good progress. I have had the car idleing at 14.5AFR and revving up to the limmiter on partial throttle. The map was wrong which meant the engine ran leaner and leaner as the revs increased. This is a simple programming issue and demonstrates that the device is perfectly capable of driving the 944's DME. Should be ok for LUX/TURBO/S2, the only thing it wont cope with is early DME's with 12v driving the AFM. This could be corrected by designing a different circuit.

I'm taking a week off next week to go back home and service my new 951 but I will also be continuing work on the MAF converter (on my lux).

toddk911

I run the 2001+ Ford Lightning SVT 90MM MAF (Hitachi)

Plug and play with chips or piggy back. With data logs at 20psi and about 350-370whp I see about 4.2v at redline.

I have flow charts for it also from the factory for a wide range of rpm for chip matching. Can support 500whp easy. Many to be found on craigslist or ebay about 150-250$.

I found this and the info on it when researching the Schivision.

Maxed it can handle about 1,200cfm.

barks944

Could you send me the information on the Hitachi MAF. If I had good test data for a MAF meter, mapping would be much easier. Also I could do with air flow vs ouput voltage for the late version of the 944's AFM. That information should take much of the guesswork and trial an error out of mapping.

toddk911

No problem.

I can send it (flow vs volt) in a bit when I get home from work.

http://www.superchargersonline.com/p...=MM-V8A003-040