Eliminating an AFM in Fuel Implant Mode

[spddm0n]

Hey guys -

I'm a little confused as to whether or not I can eliminate my AFM (on my MR2) while using the fuel implant mode. I was reading a post on a Supra forum suggesting that if you use piggyback mode, you can convert the generate the required AFM signal to the OEM ECU by using a table referencing the DET3's internal MAP sensor. That makes sense to me.

The question I have is...if I use the fuel implant mode to direct drive the injectors, can I still eliminate the AFM? Do I still use the internal MAP sensor and an internal table reference to generate and send a signal to the OEM ECU, rather than the AFM? If so, am I still "tricking" the OEM ECU into thinking there is less load on the engine (like piggyback mode) and thus have an issue with timing advance? Does this unit generate a MAF signal from its own internal speed density calculations?

My concern is managing timing advance with a system that is tricking the OEM ECU into detecting lower load levels and advancing timing. How do I control timing advance with the requirement to provide a signal to the OEM ECU from the AFM?

Thanks!

[bondango]

In FIT mode you use the internal MAP sensor as your load reference to control the injectors directly - The stock ECU has NO CONTROL of the injectors while in FIT mode. As your are NOT fudging the AFM signal, the Stock ECU will not compemsate by adjusting timing
You will be required to add a AIT Sensor to the DET3 and fit a 2.2Kohm resistor on the AFM circuit for AIT (as ait is measured via the AFM)

[spddm0n]

In FIT mode you use the internal MAP sensor as your load reference to control the injectors directly - The stock ECU has NO CONTROL of the injectors while in FIT mode. As your are NOT fudging the AFM signal, the Stock ECU will not compemsate by adjusting timing
You will be required to add a AIT Sensor to the DET3 and fit a 2.2Kohm resistor on the AFM circuit for AIT (as ait is measured via the AFM)

Ok, great. Yes, while in FIT mode, there is not fudging ECU with fuel, but there still must be a signal sent to the ECU from the DET3 about engine load, so that it can understand what to do with timing.

So, while in FIT mode, with no AFM, how does the the DET3 know what signal to send the ECU from the (now removed) AFM? Is the "learning" mode is REQUIRED to build a 3D map or some kind of table of load information that can be"related" to the internal 4 bar MAP inside the DET3 to communicate to the ECU once the AFM is removed? If not, how else can the DET3 know what AFM the vehicle "had" in place and what signal the ECU is expecting in order to determine the correct timing?

Also, what happens when the airflow (boost) and matching fuel levels exceed the maximum signal the DET3 can produce for the ECU (on behalf of the now missing AFM)? How does the ECU know what to do with timing beyond the original air flow meter capacity? In theory, the air flow signal (from the DET3) to the ECU will remain constant, because it really can't determine anymore air flow beyond the design of the AFM. Will the timing simply stay constant as well? RPM will be increasing and air flow will "technically" still be increasing (increasing boost), though it will appear to the ECU that the airflow is remaining the same. Therefore, will the timing will also stay constant? If so, this is good as timing can be added, if desired, using the maps. If not, this could be a big problem if timing is being added, but we simply don't know how much and it becomes a risk to know how much timing to "pull" out of the maps.

Lastly, does anyone know if the learning mode produces a 3D map of timing values as well as fueling values?

[bondango]

Ecu will still require its load input, either using the stock AFM or building a load map from it (AFM elimination)
Timing adjustment beyond the stock map is not an issue as you are using the det3 load map to adjust timing. The ecu will apply a timing figure at its max load on its own internal map, above and beyond that, this value will be adjusted via the DET3.
DET3 will only build a table for the load signal (AFM) not the timing.