MoTeC Global Forum

Hi guys,

I've got a question in regards to fuel consumption on my mitsi 4g63.

I'm just wondering why my MOTEC M4 ecu'd mitsi with very very similar specs to my AUTRONIC SM4 ecu'd mitsu consumes more fuel?

The SM4 ecu'd car runs a bigger turbo / bigger injectors / bigger fuel pump and makes more power.

Both tunes were done by the same tuner so I'm confident that the tunes are good. Is it something to do with the generation of technology? Is the SM4 just better or can something be done with the M4? Does it need more tweaking?!?!

Any advice appreciated!

fuel consumption isn't always about tuning. it is mostly tuning but there are other things that can affect.
actualy small turbos can make worse fuel consumption when it's starting to boost on lower revs making every stand start with boost.
also some mechanical stuff is affecting fuel consumption, especially if the can isnt tune with them to begin with,
spark plugs, air filter and stuff like that.

i have tuned varius ecu's. motec haltech autronic and more. i have never felt that i can get better fuel consumption
in one ecu in oppose to the other.

i think that the root to your problem is the tuner. you might have got not the full service of this tuner as much as the other guy who has autronic.
is it possible that the tuner is usually deals with autronic and not motec?

The tuner is qualified for both MOTEC and AUTRONIC.

Same tuner, same dyno, same engine builder.

Could it be that the Motec may just require more tuning time in order to achieve the same efficiency as the SM4?

I might have to get it back to the tuner and try and get some more efficiency out of it.
Are there any tips on making it more efficient?
Does the M4 have any features to improve efficiency? ie fueling settings on cold start / fuel settings on decel etc etc?

as i said before, i have tuned both autronic and motec.
i don't think that sm4 has any advantages in fuel efficiency over the m4.

"fueling settings on cold start / fuel settings on decel etc etc"
ofcourse it does, this is not even a question. sometimes not all functions are used by the tuner but it is
his problem and your problem with him.

How about cams and cam timing... Are they the same?
Compression ratio... Is it the same?
Otherwise the injectors.
The ECU only controls things.

If it on a real car then other things come into play, like weight, tyres, and aero.
So probably BSFC at a variety of RPM and throttle position is the best comparison - using a hub dyno

Its irellevant what ecu is in the car, my old evo 9, stock engine, stock turbo ,m800 ecu and it was quite heavy on fuel, now i have an evo 8, forged,gt30,cams,1000cc injectors,also running m800 and it much more economical on fuel, more lag, and the car doesnt use as much petrol. Also running closed loop, helps alot.
Its all down to how maps the cars

And your right foot!

Ok, with some advice from Jamie A from Motec and Jayz-1, I have noticed that the Fuel Overrun function was disabled (which I have now enabled) and also that the injection timing was set on default values (which I have changed).

I'm hoping that this will improve the efficiency of the engine. It has already allowed me to reduce my idle fuel values by a couple of values and also decrease idle igntion timing. So far it has stopped the irratic idle and random stalling.