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General Tuning Tips for Datalogit FC Edit on RX-7

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Hi Guys

I am playing with a Datalogit on an FC3s (its running an EP Engineering Power FC for a S5 TurboII RX-7

I have had a good read through the instruction manual that come with my Datalogit however i am still puzzled by some of the maps on the software.

And the order in which I should go about tuning each map.

Here are my assumptions so far.

INJMAP - displays ARF/LAMBDA/Correction

This looks like what I would assume to be a target AFR or Lambda Map however i do nut cully understand what the correction version is for.

IGLMap - Leading Ignition Timing

I am assuming this is ignition timing for the leading coils BTDC


As above but for Trailing Coils.

BASEMap - Dosplays Base (msec) / Base x INJ (msec) / Headroom (msec) / Fuel Duty %

Base (msec) - i am guessing i treat this a little like a VE map where i would alter the numbers in this table in order to rear my desired AFR/LAMBDA for the same cells in the INJMap.

Base x INJ (msec) - i am totally puzzled what this one is currently for so any tips of help on this would be great.

Headroom - I am guessing this is displaying the injector duty cycle that is left for the injectors inputted on the injector date. giving you an idea of just how much more fuel capabilities the fuel system has in a designated load cell?.... or am i totally wrong.

Fuel Duty % - I am assuming this is the injector duty cycle for a given engine load cell.

Tuning Procedure

from my understanding of following some of the courses on here - as there is currently no Datalogit course available (hint hint)

after setting all the relevant values in the settings pages of the software I would want to set my target LAMBDA in the INJMap table - there is obviously a base map in the FC Edit software for the FD however i pulled my base map from a reinitialised AP Engineering FC3s ECU.

With the Target LAMBDA set and assuming the ignition timing maps are good then i would do to my BASE (msec) map and begin to dial in the numbers to get the desired LAMBDA from the my engine that matches those numbers in the INJBase Map settings.

What does the Correction Map do or tell me?

Once this is all done would I then be able to alter the target LAMBDA in the INJBase Map and have the ECU do the calculations for me?

Sorry for the long post and all the questions, but i have rear the original FCEdit manual several times over and find it lacking in explanation for how many of the aspects interact.

I look forward to your replies guys and thank you in advance.

I see the Forum seems to be looking a little busier, so hoping someone may be able to shed some more light on this one for me.


The PFC/Datalogit hardware/software combo is a somewhat odd archaic and esoteric setup that a lot of folks pretend like they have a good grasp of.

Last I checked Ray (Arghx7 I believe) curates a yahoo group that has a wealth of pretty good though at times frustratingly apocryphal information. Years ago I believe he was charging for access, not sure now. They also have a bunch of 'tools' (spreadsheets essentially) to help speed the process.

The PFC has a good timing and event system but much of everything else about it is pretty hacky, most of the people involved in tuning it on a hobby basis do so with a heuristic approach and tend to not be as systematic/empirical as the HPA's.

I'd also check out rx7clubs PFC subforum before you start, once you sift through it a bit there's of good info. Also feel free to shoot me a pm for specifics once you have an idea of where to go.

We usually reply within 12hrs (often sooner)

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