anesthes

iTrader: (12)

Anyone here doing MAF and MAP ?

While it's winter and I'm changing things I'm tempted to use a MAF sensor for idle and low load/rpm. (maybe idle to 2000) and then switch to VE.

Just curious if anyone has had any experience doing this?

http://www.microsquirt.info/mafmap.htm#ms2

-- Joe

anesthes

iTrader: (12)

Seriously. Noone ?

-- Joe

TTOP350

iTrader: (8)

LS1 uses both sensors like that. How would you set it up?

anesthes

iTrader: (12)

I'm thinking MAF from idle to maybe 1500 or so RPM, then blend into MAP.

Alternatively, I can do main fuel table MAF and use MAP for triggers like boost spark/fuel, wastegate, etc.

Curious what others have done ??

-- Joe

TTOP350

iTrader: (8)

How do you wire it in to work? (im not a ECM guy sooo just curious?)

Tehsocks

Like a previous poster said, the LS family of engines do the same thing.


They use MAF for idle and steady state conditions (upto 4500rpm i think)

and use MAP for "transient" conditions, because of the slow response of MAF sensor.

anesthes

iTrader: (12)

My ECM supports both, then it's a matter of configuring the software.

http://www.microsquirt.info/mafmap.htm#ms2


I didn't realize LS1 PCM's worked like that. I always thought LS1 was MAF only. Interesting..

-- Joe

anesthes

iTrader: (12)

So I was doing some reading and it appears it's backwards from what I would have thought?

it looks like the LS1 stuff using MAP for idle and low load, and uses the MAF for hig rpm/high load ?

-- Joe

anesthes

iTrader: (12)

I've been playing with this more on the test bench and wanted to bring it back up.

So I've decided rather than using the "blended" logic, to use a primary fuel load of MAF, then switch to MAP as a secondary fuel load when MAP goes > 100kpa.






The MAF sensor uses a fuel curve calibration, which is obviously a table of voltage and grams/second flow. The first fuel table is the "trim". Values can be 100% (as in, maintain AFR based on actual grams read, and target AFR looking at wideband o2), or a value can add or remove fuel. This is your main correction table.





I decided to use fuel table 2 as a "multiplicatin" table, so obviously 120% in a cell means "Add 1.2 times the fuel". This essentially creates a 2d boost multiplier.

My ignition table is based off MAP, and goes to 190kpa.





And of course I'm using Wideband o2 closed loop, with a target AFR table. (Rather than some lame global AFR target)




Even though I'm using MAF < 100kpa, the ECU calculates VE based on airflow read and engine size, so the closed loop AFR target table is based on "Ve load".


So now the only question I have is, what MAF should I use.

Since I'm only using MAF for measurement off-boost, I'm not sure if I should pick a MAF with a flow range of 0-264 grams/sec for more finer resolution, or pick a MAF with 0-600 grams/sec that can report airflow even during boost.

I think in theory I shouldn't have a flow rate that exceeds 264 grams/sec unless I was actually in boost.

Either way, the Ford MAF's seem like the best choice. It's a drop in style sensor, so I can use a billet housing and try different sensors.



-- Joe