GRS Posted March 20, 2023 Report Share Posted March 20, 2023 Hi, I have a question about load source settings for equations. It is very basic and a bit embarrassing, but I would like to understand it. The car is an MX5 NA model, BP engine. Throttle ITB. The main map load axis is TP and the equation load source is MAP. Using the second map, the load axis is corrected as MAP, but I am beginning to wonder if the current settings are really appropriate as the atmospheric pressure correction may not work with fuel injection. The proper setting for a non-turbo engine with ITB is, as the help says Load source of the equation: BAP Main map load axis:TP is it? Also, is there anything to keep in mind when changing the equation load source from MAP to BAP? Regards. Quote Link to comment Share on other sites More sharing options...
Adamw Posted March 20, 2023 Report Share Posted March 20, 2023 BAP or MAP is generally fine as the equation source for road car ITB engines, both will give you baro compensation. If you have an idle valve then MAP is a must. On NA race engines with high valve overlap the MAP is generally too noisy and results in noisy inj PW so BAP is usually more suitable in those cases. The other slight variation I sometimes do for well designed race engines is set the load equation source to MAP but connect the MAP sensor to the airbox so you get baro comp but also correction for aero or restriction effects on the airbox. castillaricardo 1 Quote Link to comment Share on other sites More sharing options...
GRS Posted March 20, 2023 Author Report Share Posted March 20, 2023 Thank you very much. Why is it mandatory that the load axis in the equation be MAP if there is an idle valve? If the load axis of the main map is TP, does this affect the fuel injection at idle? Or is it because MAP is used as one of the flags for idle on? Quote Link to comment Share on other sites More sharing options...
dx4picco Posted March 20, 2023 Report Share Posted March 20, 2023 when the idle valve is opening and closing (varying load) at a given rpm, the intake pressure increases or decreases. if you have no map sensor post throttle to see this change, AFR will be out of wack, lean when ecu opens the valve and rich when closing. load axis in TP is ok, then combined with map load source Quote Link to comment Share on other sites More sharing options...
Adamw Posted March 21, 2023 Report Share Posted March 21, 2023 Yeah, for ITB's with an idle valve, fuel map still uses TP, just the equation load source is set to MAP so the fuel equation can compensate for the air that the idle valve is bypassing. Quote Link to comment Share on other sites More sharing options...
GRS Posted March 21, 2023 Author Report Share Posted March 21, 2023 I was able to understand about equation load sources. I was also able to confirm that I am not doing anything wrong. Thanks to both of you. Quote Link to comment Share on other sites More sharing options...
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