Anything about Ford EEC tuning. TwEECer and Moates questions dominate, but there's some SCT and OBD-II knowledge too.

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OzFalcon
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Posts: 81
Joined: Sat Aug 23, 2014 8:50 am

Lean cruise (MFA) (MPG) mode not switching on sometimes

Post by OzFalcon » Sun Apr 09, 2023 8:23 am

hi guys, im having an issue where the car wont go into lean cruise consistently..

i am running a stock tune WANA australian 6cyl 4.0 falcon..

it usually goes into lean cruise when cruising but on the last couple of long hwy drives it has refused to enter..
i am monitoring it using a windband and can see when it does/doesnt.. afr will drop down to near 1.3 Lamda when in lean cruise..
i am wondering what does the ecu look for to decide when to activate the MFA mode..
is it time? time since what?.. is it temperature?.. i know it limits it by RPM and load as it will jump out when u put your foot down..
i thought it might be temperature related.. i have noticed the temp sits around 86 (Celsius) when cruising at 100kph.. the other night though the temp was moving between 82-87 fairly rapidly making me think the thermostat might be too cool and perhaps affecting things..

i know it isnt something that most people care about but some might find it interesting and know how it all works or can point me in a direction to find an answer..
Primary car : 1999 Falcon AU 1.5 australian 6cyl
ECU : EEC-V
WANA / 9XL1N6
EDIS with Speed Density
Using TunerPro / Quarterhorse

from Vic, Australia

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xd41efisc
Regular
Posts: 100
Joined: Wed Jan 21, 2009 5:21 am
Location: Perth, Western Australia.

Re: Lean cruise (MFA) (MPG) mode not switching on sometimes

Post by xd41efisc » Sun Apr 09, 2023 6:55 pm

I don't know if AU is the same, but I have read that EL needs the power steering pressure switch to be working properly to enable MFA.
Ford XF Falcon 4.1/250 EFI Xflow, Eaton M112, Water/Air intercooler,
C0S/GURE ECU, 42# Injectors, 90mm LMAF, AEM wideband, QH, BE/EA.

Ford XF Fairmont Wagon, 5.0 Windsor, A9L/GUFB.

OzFalcon
Regular
Posts: 81
Joined: Sat Aug 23, 2014 8:50 am

Re: Lean cruise (MFA) (MPG) mode not switching on sometimes

Post by OzFalcon » Sun Apr 09, 2023 8:23 pm

xd41efisc wrote: Sun Apr 09, 2023 6:55 pm I don't know if AU is the same, but I have read that EL needs the power steering pressure switch to be working properly to enable MFA.
nope i havent heard that.. cant see how that would tie into it..
Primary car : 1999 Falcon AU 1.5 australian 6cyl
ECU : EEC-V
WANA / 9XL1N6
EDIS with Speed Density
Using TunerPro / Quarterhorse

from Vic, Australia

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