Zytec ECU settings

[marekh]

Dear fellow JEC members,
I am interested in looking at the ignition (and/or fuel) map settings housed in the Zytec ECU, probably on the 6litre cars. This has already been described elsewhere on this forum as a 24 x 16 table.

What I'd like to deduce is what the x and y axis unit values are for the ignition and/or fuel tables are. This should be possible either with the Zytec software loaded onto a laptop or via OBDB1 and a hand held scanner.

With engine running, if the indicated ignition advance, MAP and rpm are written down for a number of datapoints, then it ought to be able to locate these reasonably accurately on the 24x16 ignition table to verify the rpm axis. (If you rev the engine up with an OBDB1 scanner on it, then you can record advance, MAP and rpm while the car is stationary.) To deduce the same for the y axis (MAP), it'd mostly be necessary to have an assistant write these down on a car which is out on the road with the OBDB or Zytec software running, as the MAP settings will not move about much on an idling car.

The overall ignition pulsewidth commanded can also provide this information, but only on a car which is fully warmed up and with constant inlet air temperature and only very mild movements of throttle - you'd have to take it out on the road while the scanner or software is attached.

Essentially, I know what is in the tables, but I don't know what the values are on the x and y axes. I can make some informed guesses just from the shape of the data in the tables and the basic knowledge that Zytec set it up to idle at 750rpm with 4' advance and that it was at 4500rpm and 20' advance with no vacuum attached, but knowing a bit more information will give some insight into where peak torque occurs and how Zytec wanted to tune the car to tune out any quirks in the v12's operating characteristics.

kind regards
Marek