ITB RB26DETT Motec M84 main load choice for fuel tables

Hello everybody,

a quick presentation needed to understand my level of preparation.

I am a diagnostic (scope guy here) and engine builder working at a Ferrari dealer as well in my own small environment.

I personally own an R33 GTR with forged internals and many goodies built by me and I use it as a track-mountain tool.

I’ve started to breathe EFI tuning while driving my car on the rolling roads assisting the tuner (who know is a menthor) while calibrating the Motec M84 I’ve wired and installed in the car.

It’s been two years struggling around ultra lean areas while stepping on or modulate the throttle on racetrack curves. Exiting them curves is a terrible feeling. He lives quite far from me so I’ve started to play around the software myself with his telephone help at first. Populating fuel accel tables the problem softened a bit but still much present.

now I’ve decided to solve this and step up as a tuner and subscribed to HP academy EFI courses, best choice I could make! I’ve first of all understood about alpha-N necessity for ITB engines like mine and then watching the dedicated webinar I finally felt the solution close to end my problems.

my concern is that M84 is quite different from the newer Link ecu taken as an example on the webinar. Also it’s alteady been tuned using MAP as main load, though it looks like (if I’ve correctly interpreted the instructions in the F1 help) there is a second fuel table ehich I can set to TPS as load dedicated to ITBS tuning.

is it how I am supposed to solve the situation? Populating this table and leaving the MAP as main load on the main fuel table?

car made 631 hp on brake dyno

THANKS for the help.

Ps there is an important time attack event in 20 days and I need to be ready somehow!🤣🤗

With the efficiency calc set to TP, the hundred series still factors in MAP in the background via the MAP comp table. So this is fairly similar to the Link example

The biggest difference is from memory the hundred series doesnt consider the lambda target table in the PW calculation - whereas with the Link example the lambda target is a multiplier in the fuel PW so for ITB turbo we typically reference MAP on the axis of the lambda target table so it commands a richer target as manifold pressure is increased (and it changes inj PW, not just the target). In your case you could just tweak the MAP comp table so rather than it being the default 1:1 multiplier, it instead adds a little more compensation in proportion to boost.

Hello Adam and thanks for the hint.

if I change the efficiency main load to tps even trhe lambda target table switches to TPS.

What about changing the secondary fuel table to TPS and use the tps as a corrector? May it work?

it could be a good test meanwhile we organize a proper dyno session to start again with a new main load TPS setup.

also the lambda target table y axes stays in Kpa and not in tps

Andre experienced something similar in the old HKS F-Con V ecu, at least that’s what I’ve grasped

The M84 was made as a lower cost option for basic applications so a lot of the flexibility of the M800 has been removed.

However I wouldnt consider the lambda target table referencing TP a big deal, and my general philosophy is always to keep it as simple as possible, avoid adding complication unless it is absolutely necessary. So I personally wouldnt jump straight to reinventing the wheel with secondary load tables etc.

I would change the eff calc to TP, leave the MAP comp at the default 1:1 initially, tune the alpha_N fuel table at lowest boost setting so that lambda matches target. When that table is tuned, then increase boost to max setting, do a test run to see how close lambda stays to target. It will likely drift richer than desired at higher boost, if it does then just reduce the relevant cells in the MAP comp table that are in effect at the higher boost setting. The MAP comp table should retain the default 1:1 multiplier for all cells up to the min boost value, then above that you will likely only need a single cell to correct the highest boost level, with linear interpolation acting between the min and max boost compensation cells.