radu_rd2

1. What you do to get rid of MAF is use the FIC to compute a MAF voltage based on MAP and RPM. Basically a MAF simulator which is MAP based. The hope is that under non-boost conditions this voltage is close to what the ECU would have gotten from the real MAF anyway. The aempower forums have a tutorial on how to get a map based on N/A logs. You do NOT start from scratch with any fuel/timing maps.

2. Clamping means limiting the highest MAF value the ECU sees, so of course clamping will not affect vacuum. Mainly the point of clamping the MAF is that under higher pressure the FIC will add fuel anyway, so no point in having the ECU increase fuel a bit too due to the increased airflow.

3. The FIC controls the injectors but if you use a percentage map it will SCALE whatever the ECU wants to send, so what the ECU is trying to do is still relevant..

David Dickson

There a couple of reasons I feel putting the MAF might not be the best idea. I mean for a lower power setup I'm sure it works fine but look at ALL the OEM set ups and the ones that use a MAF ALL have them in the turbo intake pipe. From what I can gather the reason why this is, is because Its difficult to manufacture a durable MAF element that will survive under the varying boost pressure and temp situations. Plus eventually the MAF housing itself will crack apart. Oh and don't forget a MAF sensor likes to have a nice straight air flow through the element to be able to calculate 100% accurate fuel requirements.
I think as long as you stay below 20psi of boost you should be fine though if you start seeing drastic changes in your tune you might have a damaged MAF sensor or a cracked MAF housing.

elitetuning

controlling each injector? The fic is now in control?
From what i understand the FIC is never in control..its a piggyback. I don't know if what you said is correct.. If you DONT clamp the maf voltage...and its still on your intake, or charge pipes...it WILL see increased air flow, and thus add more fuel...won't necesarily freak out, but will still try to adjust for increased airflow..so i think that is why you have to clamp it, like radu said, so it doesn't see past a max voltage.



excellent information, i'll see if i can find that on the aem site. The only thing about this that sounds bad is that we have to drive the car NA to get these logs..and also..we are not sure if her MAF sensor is working properly. So the voltages may be incorrect.


thanks, i understand what you mean! This is why i didnt think what Jay-M said was quite right...because if you don't clamp the MAF voltage (when ur keeping the MAF) then it will still try to compensate for increased airflow..and so will the FIC.



hmm..now i can see how Jay-M might still be correct. If you don't use percentages, then technically it looks like you don't have to clamp the MAF whenkeeping it..because the value in the FIC cell, is a "Raw value" not a scalar. Right?

radu_rd2

Either way the MAF will hit a voltage limit, and I think the FIC will put out a MAF signal to the ECU of at most 5 volts, so you have a 'hardware' clamp in place anyway. Max N/A voltage seen on my car (WOT@6000rpm) was around 4.4 volts i believe.

The FIC is always physically in control of the injectors. However the preferred method of tuning is to base its decisions on the ECU injectors outputs (for example, having the FIC do exactly what the ECU wants to do under no-boost conditions).

David Dickson

The FIC can be installed several different ways. One is as a passive fuel controller which means it just modifies the OEM MAF voltage to compensate for larger fuel injectors. This would be like what NEO does. Or it can be installed as an Active system meaning that it can intercept the OE injector pulses and modify them taking direct control of how much an injector pulses. In this configuration the OE pulse is only used as a baseline for the FIC so depending on what percent positive or negative you put in the load cell is will either increase or decrease the pulse width of the injector. If you install larger injectors you would obviously want to decrease the amount each injector pulse because each pulse will contain more fuel.
A third way is that the FIC can control auxiliary injectors much like the SMT6 does to add fuel.

elitetuning

great info!

I'll have to look in the instructions to see about doing it the "active" way so to speak. I assumed there was only one way to wire the injectors. i didn't see two different ways in the instructions.

radu_rd2

there's only one way to wire the injectors lol, dmdicks just said that you can not wire them at all, or wire them, or wire secondaries while leaving primaries on the stock ECU

elitetuning

i didnt mean like wiring them differently as in modifiying the fire order, or groud switched or anything like that...

I re read what he typed..turns out i already knew what he just said.

i understand that you can intercept maf voltage, and control fuel that way by tricking ecu into thinking its somewhere else in the maf voltage map
OR
intercept injector signal and modify pulse width. That sounds more along the lines of what we'll probably do.

I sound so slow right now, because i haven't actually had time to even take it out of the box because of other things we're fabbing up for her car and mine. Once we get it out of the box and wired in alot of this will make alot more sense.

Jay-M

Do the injector intercept setup... you will have a semi standalone setup but you just need to tune every part of it's operation; start up, idle all the way to boost