Multiple map sampling technique for ITB equipt cars

[Fred]

This is brought to you courtesy of "im2fast4u" from msefi.com who allowed me to reproduce his image provided I referenced him which I am of course happy to do.

Here is his schematic and implementation :





The thread :
http://www.msefi.com/viewtopic.php?t=29502

His posts :
http://www.msefi.com/viewtopic.php?p=191572#191572
http://www.msefi.com/viewtopic.php?p=191616#191616

A clever and simple idea.

If you have an ITB equipt car, I suggest you give it a shot :-)

Admin.

[Fred]

It seems to me that you could gain some benefits from using a setup like this on a vehicle with a normal single throttle too. Manifold pressure is not constant across all the runners under those circumstances either, it's just that the effect is much less pronounced because of the larger "tube" joining them together. I can think of a simple way to use the spare ADCs for sampling this directly, though it seems like a waste of ADCs to do it that way when external methods are available.

I was going to post this on msefi.com, then I thought, no, stuff it, it can live here, they don't want my contributions anyway :-)

[SleepyKeys]

My Yamaha R1 engines uses Y fittings tied to each other to connect to a single MAP sensor.





Port Port Port Port
| | | |
-------- -------
| |
----------------
|
MAP

-sean

[Fred]

Yes, most of them do it like that, I have some GSXR throttles that are similar. One must assume that their MAP sampling technique is superior to the existing variations. In fact, the reason given for this is that map fluctuates too much without a damper, and with a damper the response is too slow. the fluctuations are what you want to read. Good sampling could probably capture that data. Still, even without a damper, there is still an equal feed (even if directional) and the vacuum wouldn't be as low as a multiplexed system like this. Interesting stuff to think about anyway :-)

[Tony]

Hello im new to the board and i really like the board so far from what i have read it looks VERY nice and some exciting things will come from here im sure.


I have been thinking of throwing one of these boards together myself . I mess with bikes alot and i have a stock Hayabusa Denso ECU apart right now i will trace the signals for the map sensor out and see what i come up with it uses one map sensor and a baro sensor for baro corrections it might give some insite into how they did it.

One other thing to note on most ITB the nipples usually have a small orifice inside the nipple to help dampen the pulses to the sensor itself.

[Fred]

Hello im new to the board and i really like the board so far from what i have read it looks VERY nice and some exciting things will come from here im sure.

Welcome aboard! :-) I certainly hope you are right!

One other thing to note on most ITB the nipples usually have a small orifice inside the nipple to help dampen the pulses to the sensor itself.

I didn't know that. Thanks for sharing :-)

I look forward to reading about your findings.

Admin.

[Tony]

Here is a schematic from the stock Denso ECU on a Hayabusa from the map sensor to the CPU no remember most motorcycle ECU's dont use map only they blend map and tps they use map up to about 10% tps then tps takes over so i dont think the circuit from this ecu would be of much help for insite as it seems pretty simple .

[Fred]

Someone elses implementation :





Admin.

[shameem]

I can think of a simple way to use the spare ADCs for sampling this directly, though it seems like a waste of ADCs to do it that way when external methods are available.

Why not use a switching method to sample individual MAP sensors directly using one ADC pin....



This probably requires a good knowledge of piston position - but is it more complicated than the requirements for seq injection/ignition....

[Fred]

I wasn't aware (naively?) that you could MUX analog signals like that. Can you link a part number to read about?

Admin.