fuel consumption while braking with engine

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klement
Posts: 80
Joined: Mon Oct 17, 2011 4:30 pm

Hi,

I have the 2011 model with CVT and I'm using an OBD scanner with "torque" app to monitor the engine, mainly for fun. I noticed a strange behaviour:

When I put my foot of the gas pedal, the car naturaly starts to slow down. In this case I see 2 possible scenarios.

1.) if the speed is above 80km/h, both torque and onboard computer show 0l/100km. this is expected and ok.

2.) if the speed is below 80km/h, the onboard computer shows 0 (no bar shown), while torque shows ~2l/100km.

Another interesting fact is that if I downshift and raise the rpm to say 4000, this consumption goes up (3-4l/100km). I would understand why if this was an old carburettor based engine, but of course it isn’t :)

Anybody else playing with tools like this and noticing any strange behaviour like this?

Regards,
Klement
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Moto
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I find the reported values unlikely... It is probably just poor programing on the feed back. It should consume close to zero on a downshift.
WESHOOT2
Posts: 1976
Joined: Tue Jan 11, 2011 5:37 pm
Location: Vermont

Since I regularly downshift my 2011 S AWD CV-T to retard forward mo, I've thought about whether the fuel system sprays a bit of cooling gasoline when not on the throttle.
Yes I have.
klement
Posts: 80
Joined: Mon Oct 17, 2011 4:30 pm

Well that doesn't make much sense. When the engine is not being fuel-fed, then there is no heat from the combustion process, rather the air which is still flowing through it cools it. Also, why would it do this only when the speed is < 80km/h?
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NiteRider
Posts: 179
Joined: Wed Mar 21, 2012 9:22 pm
Location: State College, PA

Brake assist have something to do with this?
'12 Kizzy GTS - Azure Gray
'10 Jeep Liberty
klement
Posts: 80
Joined: Mon Oct 17, 2011 4:30 pm

I think it shouldn't. Since the engine is being moved by external source of power (wheels and the cars inertia), all other systems that get power from it can continue to do so. No need to add fuel, there is no way for the engine to stutter or shutdown while the car is moving faster than some small (5?10?kmh) speed.
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11zukizashi
Posts: 282
Joined: Sat Jul 07, 2012 2:03 am

Which bluetooth adapter were you using? I just ordered the super mini one from amazon ill post my results when i get it
klement
Posts: 80
Joined: Mon Oct 17, 2011 4:30 pm

I have the OBDKey from UK.
Meanwhile, there was a bug found in the OBD software, so kizashi does not really burn fuel in this situation, as expected.
Blackbelt
Posts: 167
Joined: Wed Nov 24, 2010 3:18 pm

All modern cars have DFCO(deceleration fuel cut-off). When you are off the throttle, and the RPMS are above idle, the fuel injectors cut off all fuel.
2010 Kizashi S AWD
2009 Suzuki SX-4 Touring AWD
2008 Smart fortwo Passion Coupe
2007 Dodge Caliber R/T AWD
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