ECU load sites - Discuss

Competition engines and ancillaries - general discussion
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ECU load sites - Discuss

Post by Testament » October 30th, 2006, 6:01 am

How significant of a difference is the number and location of load sites? For example, (ignoring other features) An ecu which is mapable every 500rpm, versus another ecu which you can select the rpm of each load site (and possibly have many more sites).

Now of course having more sites, at points of your choice is better, but how much better? It would be good to hear some first hand experiences and opinions.

thank you

Guy Croft
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Post by Guy Croft » October 30th, 2006, 9:09 am

From my my own experience the minimum that I would accept as 'having been done properly' is approx 7-10 degree increments of throttle from idle setting '0' to 90 deg and 500rpm speed steps from idle to max power, for fuel and ignition optimisation.


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Inserting RPM/Load Axis

Post by petert » October 30th, 2006, 12:02 pm

In the screen below I've added the 5150 RPM axis and the 51% load axis for the purpose of this discussion.

The ECU will interpolate between values both ways (load and RPM) to arrive at an injection time (or ignition advance). For instance, consider a 50% load with the following values:

3000 - 70
3500 - 80
3700 - 90

At 3250 RPM a value of 75 will be used to calculate the injection time. Likewise, 85 for 3600 RPM.

I've never had a problem with 500 RPM intervals but other people who have tuned more advanced engines, with weird resonances, certainly may have.

For load, there is definitely a benefit getting as many intervals as possible where you need them. If you go to the Haltech review I did, compare the fuel maps tuned by TPS and MAP. Notice how there's only 7-9 usable bars in the TPS map, before the injection time flattens out. Where as the MAP example has 20-22. It would be handy to have few more load points in the first 25% of the throttle opening so the gap between injection times isn't quite so extreme.

So in reality, the load axis(s) I've specified below are relatively useless for an engine sensing load via TPS. More need to be added below 30%.
autronic insert axis.jpg
autronic insert axis.jpg (35.02 KiB) Viewed 2956 times

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