i have a little problem after i did a stage 1 ecu remap
my mpg has decreased significantly
when driving in town i can see the km range drop every 5 - 10 seconds by 1 km
example whan i start up the car i have 250km left on fuel and after mayby 5km of driving it dropped to 210,while driving very normal
when driving on the highway and using cruise control it comsumes fuel normally (or even better?)
does anyone knows what the problem is?
its a bmw 520d - year 2010- manual - 163hp version
i have asked the tuner to just push the engine to it's limits without dangering the car components
i did not ask him anything about fuel efficiency
could it be that he remapped the engine so i have non stop torque at the low rpm's (like 0 - 2000 rpm)
if so, would lowering the torque from 0 - 2000 rpm will get me a better fuel efficiency?
i have added a picture, these are the results of the remap
thank you in advance
Hello. welcome. for your info this is a Singapore car forum, hence many topics are linked to singapore.
regarding your concern on the torque, you can see from the torque lines (orange lines that looks like an inverted "V") that the before and after is different only at 2000rpm. the torque before 2000rpm is the same as stock. Therefore, your suggestion of "lowering the torque from 0 - 2000 rpm" will not change anything.
regarding yoru concern on mpg decreased after ecu remap. ecu remap isn't some magic of just changing your torque vs rpm graph. it requires changing parameters such as ignition timing, fuel injection timing and cycles, fuel pressure, throttle input maps, torque limiting map, turbo boost etc. increasing torque can be as simple as removing the torque limiting map (though it's always not so simple). In your case, I don't know what the tuner did, but he might have adjusted fuel injection, fuel pressure and ignition parameters on top of the torque limiting map. Because those are changed, it affects your engine performance at all rpms, so driving around town will give you lower mpg than normal.
regarding your REAL problem "when driving in town i can see the km range drop every 5 - 10 seconds by 1 km" , this is not a problem. every car experiences the same thing, and it has nothing to do with your ecu remap. the 250km range shown on your car is just an estimate calculated by the computer based on an averaged city/highway driving. if you drive around town, the car consumes more fuel due to idle and low speed driving, so of course the range estimated by the computer will keep decrease. when driving on the highway, the car consumes less fuel, so it is only normal that you will get "better" driving range. it's not technically better, because that's what the car can do originally. you only think it's better because of what the ecu tells you before.
Edited by Ishiwgao, 29 October 2018 - 05:58 AM.