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Rules instead of maps? 
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LQFP144 - On Top Of The Game
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Rufe0 wrote:
Hmmm OK I see what your saying but I just don't like the idea of a map for each cylinder, from a tuning point of view your effectively tuning four single cylinder engines which is obviously a pain. What about one proper full fuel map, then a modifier map for each cylinder which would just be +-1% or whatever in a 3d table? That way you still have a central table where 99% of your tuning is going to take place for ease of use.

From a performance stand point you have to view a mulitcylinder engine as a bunch of one cylinder engines attached to a common crankshaft. > https://youtu.be/rBZCnG1HwDM?t=3m17s
But yes a common VE table with tables for each cyl is commonly how its done for corrections


Quote:
OK yeah thats reasonable. Just wondering if the same thing could be achieved with a percentage modifier? For instance at X degrees C add 10% extra fuel. That way it's not a fixed amount like "add 1ml extra" it will scale up with load and RPM.

Generally it will just be a percentage indeed.

Quote:
A MAF needs an air temp sensor, your thinking of a MAP sensor.
I don't predict needing a map to time the fuel to valve opening, I plan to modify my engine with a unique intake system that will basically negate sequential injections benefits(and make a MAP sensor useless), regardless it's no trouble to program a basic version in. I Plan on making a few different versions just for the hell of it. Directly after valve closure, maximum time for evaporation, perhaps enable this on start and warmup. Directly before valve opening, injector would just finish as the valve was just opening. On valve opening. And some others, maybe switch between different modes for different conditions. Of course these would be offset-able, probably setup a scaling offset with RPM. All this assuming the injector pulse is short enough in the first place.


No I am thinking of a MAF sensor, which is the most direct way of reading mass. Now a MAP sensor in a SD VE system does require an AIT sensor to correctly calculate airflow\VE
I would like to know why you think a MAF sensor requires an AIT sensor.

To be able to tell the ecu like I want to injector on the valve for better MPG or while the valve is open and not use a MAP of injection timing would make me think.
A) you will need to have a camshaft model in the ecu and a way to model it correctly
b) some load variable to go with it, just because X timing is good at Y rpm doesn't mean its the same as you add load at the same rpm

Quote:
Once I've calculated the A/F ratio and injected the fuel I then need to time the ignition. To do this I will lookup the degrees BTDC in a A/F vs RPM map, calculate the time in milliseconds or clock cycles after the relevant cam position sensor using the RPM and set an interrupt.


That way I could see working maybe as an additive map but not as a main ign table map. You don't take into consideration load like that.


Sun Oct 11, 2015 3:20 am
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Quote:
No I am thinking of a MAF sensor, which is the most direct way of reading mass. Now a MAP sensor in a SD VE system does require an AIT sensor to correctly calculate airflow\VE
I would like to know why you think a MAF sensor requires an AIT sensor.
Lookup MAF's, they need an IAT sensor, otherwise they would only give you an accurate air mass reading at one specific air temperature. Sometimes the MAF and IAT are an all-in-one unit so maybe you've seen that and not realized there is an IAT built in?

Quote:
To be able to tell the ecu like I want to injector on the valve for better MPG or while the valve is open and not use a MAP of injection timing would make me think.
A) you will need to have a camshaft model in the ecu and a way to model it correctly
b) some load variable to go with it, just because X timing is good at Y rpm doesn't mean its the same as you add load at the same rpm
Unless you've got some sort of VVT then your valve is always going to open at the same time with regard to the camshaft angle.

Quote:
That way I could see working maybe as an additive map but not as a main ign table map. You don't take into consideration load like that.
The Load is built in to the A/F ratio calculation already done in the fuel map.


Sun Oct 11, 2015 10:01 pm
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Rufe0 wrote:
Lookup MAF's, they need an IAT sensor, otherwise they would only give you an accurate air mass reading at one specific air temperature. Sometimes the MAF and IAT are an all-in-one unit so maybe you've seen that and not realized there is an IAT built in?


I've seen several maf's most that IAT's generally have them going to the ECU but not for the maf, but using for spark correction. I'm going with the standard hot wire \ hot film, both these wouldn't require an IAT sensor to give an accurate air mass reading imo. push a bunch of air over thats heated up and its not gonna cool the wire as much, put a bunch of air over thats cool and it w ill cool the wire more. Seen\have several maf's I've dealt with them a good bit.

Quote:
Unless you've got some sort of VVT then your valve is always going to open at the same time with regard to the camshaft angle.

still have to factor in load
Image

Quote:
The Load is built in to the A/F ratio calculation already done in the fuel map.


So you are stuck with a system that is like a carb and a dizzy.
What happens when you want to accelerate without increase fueling? go to 50-60% throttle and stay at stoichmetric.


Mon Oct 12, 2015 2:16 am
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Hentai wrote:
I've seen several maf's most that IAT's generally have them going to the ECU but not for the maf, but using for spark correction. I'm going with the standard hot wire \ hot film, both these wouldn't require an IAT sensor to give an accurate air mass reading imo. push a bunch of air over thats heated up and its not gonna cool the wire as much, put a bunch of air over thats cool and it w ill cool the wire more. Seen\have several maf's I've dealt with them a good bit.
Clearly the warmer the air the less it's going to cool down the wire. Energy will always try to travel from an area of high density to an area of low density at a rate that is proportional to the difference in density. http://www.physicsclassroom.com/class/thermalP/Lesson-1/Rates-of-Heat-Transfer


Quote:
So you are stuck with a system that is like a carb and a dizzy.
What happens when you want to accelerate without increase fueling? go to 50-60% throttle and stay at stoichmetric.
I can only think that you mean "what happens if you want to accelerate very slowly"? Which would mean that the difference in throttle position and RPM where minimal. In that case the A/F calculated from the map would be very close to stoichiometric assuming you had the map cell for that RPM stoichiometric. In the map you could always make the next cell along from no load/acceleration be stoichiometric or close to it. Would also be simple enough to add a rule where you would have to go above say 10% of the distance to the next cell before factoring it into the A/F calculation.


Mon Oct 12, 2015 4:05 am
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Quote:
I can only think that you mean "what happens if you want to accelerate very slowly"? Which would mean that the difference in throttle position and RPM where minimal. In that case the A/F calculated from the map would be very close to stoichiometric assuming you had the map cell for that RPM stoichiometric. In the map you could always make the next cell along from no load/acceleration be stoichiometric or close to it. Would also be simple enough to add a rule where you would have to go above say 10% of the distance to the next cell before factoring it into the A/F calculation.

Not slowly, but you don't want to consume extra fuel to accelerate. ( EG. I cruise at 45mph, follow by accelerating up to 55 or 65mph which I go into boost pressure and see say 7psi of boost. Instead of adding fuel in that small time, just run it stoichmetric. )
This also requires a non static ign timing due to load


Mon Oct 12, 2015 5:22 am
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Check out this video regarding IAT http://www.youtube.com/watch?v=1pOGSCsU-T8

Hentai wrote:
Not slowly, but you don't want to consume extra fuel to accelerate. ( EG. I cruise at 45mph, follow by accelerating up to 55 or 65mph which I go into boost pressure and see say 7psi of boost. Instead of adding fuel in that small time, just run it stoichmetric. )
This also requires a non static ign timing due to load
Boost would be basically directly related to RPM would it not? So you would tune your engine around the RPM where boost would come on differently than at idle or at high RPM. In any case if you have forced induction it would make sense to have a pressure sensor.

Maybe I wasn't clear about my goals here. I'm planning to make a one off custom ECU for a specific vehicle, which is a naturally aspirated 4cylinder 600cc motorbike.


Mon Oct 12, 2015 8:23 pm
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Rufe0 wrote:
Check out this video regarding IAT http://www.youtube.com/watch?v=1pOGSCsU-T8


I saw the video.
I will tell you that yes the IAT is used for figuring out density, but thats used in a Speed Density application, not for a MAF applification that directly can read the mass of air.
Now a AFM that uses a flapper door or plunger will require an IAT sensor because its reading volume of air and needs a density correction.
http://www.amazon.com/Engine-Management ... 1932494421

Quote:
Boost would be basically directly related to RPM would it not? So you would tune your engine around the RPM where boost would come on differently than at idle or at high RPM. In any case if you have forced induction it would make sense to have a pressure sensor.

Maybe I wasn't clear about my goals here. I'm planning to make a one off custom ECU for a specific vehicle, which is a naturally aspirated 4cylinder 600cc motorbike.

yes and no, depends on what you are using, turbo\super and the setup.
Well it would make sense to have a pressure sensor to determine when you cross over, but I would also say any atmo pressure sensor as well


Tue Oct 13, 2015 12:42 am
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Regarding the earlier topic of this thread I found an interesting forum thread about software dynos http://speedtalk.com/forum/viewtopic.php?f=1&t=8126


Fri Oct 16, 2015 5:40 am
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Here is good info on hot film maf
http://www.olaf-jacobs.nl/downloads/SSP/SSP_358.pdf

We can see the temp sensor required for the maf itself is intergrated into it and has nothing to do with the ecu.


Mon Oct 26, 2015 2:27 pm
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