db944

Ok, so the engine is back together and I am ready to begin "tuning" with the mafterburner. The instructuctions say that you should tell the mafterburner what size your injectors are. My question is, where? There are two places I have found to change this. First is on the "startup values" page on the mafterburner menu. Installed injector size vs EEC for both CL (closed loop?) and OL (open loop?) on bank 1 and bank 2. Are bank 1 and 2 equivelant to Tune1 and tune2 on the graphical tuner?

the other place you can enter injector variables is on the graphical tuner drop down box.

I am running 55 lb injectors with a 3.0 bar regulator and a hi flow fuel pump. What should I tell mafterburner about my injectors vs. stock?

Thanks.

db

eospeed

On the graphical tuner page there is a spot to put in current inj size vs stock inj size.Its not that important it just rescales the curve rich or lean.I think mine is set on 19lb an 55lb.As long as the afr curve is right an the car idles well thats all that matters.

hally

your part throttle timing will be distorted if you try and cater for injector size by shifting the air flow signal in this fashion. Leaving it 1:1 in the mafterburner and getting some chips with FQS selectable injector size scaling would be cleaner.

rberry951

The mafterburner, or any other signal tuner is only meant to make small changes to dial in 'already good' baseline performance which should be provided by the chips. But chips that use the FQS to select injector size aren't the best way to go. The FQS switch uses an across the board change in fuel, and no timing adjustments. Different injectors don't flow largely different rates across the board, so that method of sizing isn't the best way to do it. Several chips have selectable injector size via FQS, but they are all the same, an across the board sweep.

Regards,
Russell

fast951

Would you elaborate in details on this.. I STRONGLY disagree with you on the use of the FQS to select injectors size!
Of course running large injectors, idle will suffer, unless you run semi-sequential.

DB, glad to see you working on the 951.

rberry951

Stock motronic DME chips and most aftermarket DME chips use the FQS settings to change a percentage of fuel delivered across the board. Stock is 0%, +3%, -3%, +6% in positions 0-3, and those same values with a -2.77degree timing retard in the upper positions 4-7. When aftermarket chips use these settings for injector sizing they change the factory code to scale back fuel a percentage they deem fit according to the injector size's flow rate. Well, a 72# injector and a 34.6# injector don't flow that differently at idle, a little more differently to 10% duty cycle, a little more differently from 10-20% duty cycle, and largely different from 20-80% duty cycle. Given this, to change X percentage across the board based on the injector's max duty cycle flow rate is not the most efficient way to do that. Further more, changing fuel rates at any point in the PT/WOT maps requires adjacent changes in the timing maps, to provide optimum efficiency, and the FQS settings do not provide for this. This is not a generic statement, this is truth. It makes no difference if your maps have been expanded, your AFM function re-written, or what else you decide to do in the chip, an across the board scaling of fuel to match the difference in injector size is not the most efficient.

Regards,
Russell

fast951

Russell, Thank you for taking the time to answer my question.

Now, I disagree with you even more! Do you really think the FQS values are the only values changed to support larger injectors?

FYI there is more to the FQS & Injector sizing than you can imagine. A properly coded software, will allow you to swap injectors (stock to 85# as an example), and get the exact AFR at Idle/PT and WOT...

Why would the timing change if you swap injectors??? The AFR should be the same, again we are only changing injectors..

rberry951

You're welcome, always happy to answer questions

Not sure what you disagree with here. When the FQS switch is rotated from position zero to position one the scaling factor from the maps at address 0x117C (or 0x17C in 24 pin chips) is utilized to scale the fuel maps, whereas position zero selects map address 0x117B which is 0x80 (128 decimal). This is a constant that us used across the board. If someone uses basic math and determines that a 55# injector flows around 37% more fuel than a stock injector and sets the byte value accordingly to 0x50 (80 dec) then the fuel is scaled right for the top end of the injector's duty cycle, and not for the lower ranges thereof. Hence, not the most efficient way to do it. And no, there is not more than I can imagine to the FQS settings. There is not more than I can imagine to the entire code for that matter, it's only 4000 bytes of information, roughly a printed page and that encompasses three sets of maps, two of which are not used at any given time thereby bringing the actual information code down considerably smaller. The motronic itself is not rocket science, it is 80's technology and a child's toy compared to current technology. So long as you stay within the bounds of the other antiquated electronics coupled to the eprom code you can do what ever you like, move the maps around, scale the maps out for finer scale tuning, alter the 32 byte AFM transfer functions to accomodate MAF signaling, lots of things. It's not difficult at all for anyone capable. So again, I'm not sure what exactly you disagree with. My original statement was that across the board fuel changes are not the most efficient way to adapt the maps for different injector sizes.

If you change the fuel maps then the timing needs to be changed accordingly, if you change injectors without changing the fuel maps your AFR will not remain the same.

Regards,
Russell

fast951

Russell, the location of the FQS is a common knowledge. Someone already released this information. But thank you for reminding me of the locations.

A 3% or 10% or 50% mod to the fuel affects across the board.. Are you saying the larger injectors flow more only at WOT and not everytwhere else?

Again, a properly written software allows you to change injectors without having to do anything else. And you will end up with the SAME AFR... Been there done that!

There are many of features in the Motronic code that a few only knows of. All the information released on the internet is not but a subset of the Motronic. As I said, there is more to the FQS that you don't read on the internet...

Again, thank you for taking the time. Best of luck in your Motronic coding.

TT

What does duty cycle have to do with the flow behavior of an injector.

Example:

At 6000 rpm a batch system will fire 100 times/sec with a maximum possible firing time of 10msec/rev. If fired at a 10% duty cycle the injector open time will be 1msec.

At 600 rpm a batch system will fire 10 times/sec with a maximum possible firing time of 1msec/rev. If fired at a 100% duty cycle the injector open time will be 1msec.

Are you saying the injector will flow differently for that 1msec time period because the duty cycle is different?

The problem with running large injectors and only using the FQS to scale the fuel is that the scaling can reduce the injector open time at low loads to a time that is less than the response time of the injector. That is why I recoded the Motronic to implement semi-batch firing to double the possible injector time to get back into the operating range of the large injectors. Semibatch operation is completely automatic on the Vitesse MAF chips, it works when needed regardless of the injector size selected via the FQS. This is how we keep the fuel maps the same regardless of injector size. It is much more efficient to keep the fuel maps set and change injectors via the FQS.

rberry951

I wasn't trying to be condescending here, I know you know that, but I was speaking also to the other readers, inluding the gentleman who started the thread.

No, I am saying just the opposite, and hence the reason an across the board change in percentage of fuel is not the most efficient way. I will re-iterate, at idle a stock injector and a 72# injector flow very close to the same, at between 3-5msec pulsewidth (20%-35% duty cycle) the difference becomes greater, and the further up the scale, the greater the difference, right up to WOT, or full duty cycle.

Actually I think I could pull down the location of about every significant map, map-pointer, offsets, etc. right off the internet now days, most anybody can. But I took the easier route to me, decompiling the 8051 microcontroller code in a running environment, just as I did in custom manufacturing controllers 20 years ago. Again, it's 80's technology, and to tell someone like myself who has been in the computer industry for almost 30 years that there is some 'holy grail' of information about the motronic that no one else can find, well, I find it absurd.

Thank you.

Regards,
Russell

fast951

Russel,

The amount of fuel needed at idle to maintain a 14.7:1 AFR will not change. However 85# injector must be opened a lot less (less duty cycle) than a 34# injector. Does it not? A 75# must open more than a 85# and less than a 34#...
Is this not correct?
As an example a 72# injector flows 2x 36# injector. From your theory above, you are stating that this is not correct at Idle or PT.


Russell, there is no 'Holy Grail' here, just some things are not known by everyone, and there are some things that have not been made public. But if you say that you know all about the Motronic, then I'll just take your word for it. I still disagree with things you said, we look at thing differently.

Regards

TT

The stock and 72# injector flow will only be similar if you only use the FQS to try to scale the fuel flow. You end up adjusting the 72# injector pulse width to less than 1msec at that end. Once you get above 2-3msec open time the difference between the stock injectors and 72# injectors remains constant. Implement semibatch operation and you will bring that open time back into the operational range of the 72# injector. Duty cycle is not the determining factor, open time is.

Then use that 30 years of experience to implement semibatch operation and you too will find the FQS is the most efficient way to adjust for different size injectors.

rberry951

If you read all of this thread closely enough and quit looking for 'picking points' you'll find I have already stated just that.

My experience tells me to map a different chip specific to the client's modifications, including injector size. My experience also tells me not to engage in high school pissing matches.

You do it your way, I'll do it mine.

Good luck to you.

Regards,
Russell

fast951

Russell, there is no pissing contest here. Interesting that you use this terminology!

TT was the FIRST person to use the FQS for larger injectors scaling. Yes no other person ever used it before he did. However, many copies this approach since, even thoughthe FQS is half the story.
You are the one who commented regarding the use of the FQS. Your comment was directly or indirectly addressed in a negative way toward our software. We simply gave you the opportunity to clarify your position.

Best of luck to you....