Does low fuel indicator adjust ecu?

b16h22 · 11-19-2012, 01:13 AM

When the low fuel light comes on does it in any way adjust the ecu to compensate?

Uncle Scotty · 11-19-2012, 01:26 AM

mmmmm...good question...first time ive seen it in years

talvai · 11-19-2012, 08:07 AM

Not sure with older models but 08+ don't see why not. You guys have Si drive which adjusts throttle response, etc. Don't see why when light comes on you send a signal to ecu to change SI drive to another map.

Not to sound like a douche but why? Why not just put gas before you get that low? Just saying.

ringlander · 11-19-2012, 09:39 AM

Realistically i don't think it would and here is why. That anti slouch feature which keeps the fuel gauge from bouncing all over the place, would affect it. The gauge is a median, an average of the high and low point of fuel in the tank and if they did have something like that it would be baaed on pressure not level . Also if your fuel pump was going bad, it doesn't change the map it blows up your motor. And lastly its called a dummy light for a reason. These are not facts just general knowing how they engineer cars.

talvai · 11-19-2012, 06:48 PM

Quote:

Originally Posted by ringlander

Realistically i don't think it would and here is why. That anti slouch feature which keeps the fuel gauge from bouncing all over the place, would affect it. The gauge is a median, an average of the high and low point of fuel in the tank and if they did have something like that it would be baaed on pressure not level . Also if your fuel pump was going bad, it doesn't change the map it blows up your motor. And lastly its called a dummy light for a reason. These are not facts just general knowing how they engineer cars.

Think op means when light is on, which means you can tap that signal and use it to do something regardless of how much gas is left. So in theory yes you could swap maps no problem. all it is, is basic electronics and programming nothing special. That being said its like i said is it worth the work. If op is just trying to do it so he can gain few extra mpg till he gets gas not worth the work. But that's just my opinion, each his own

imma_stocker · 11-19-2012, 06:58 PM

Rumor is the ecu trims back full boost psi around 1/4 tank. No clue if that's true or not, only digging into FACTORY ECU map will tell you.

And that's how stupid rumors stay alive!

b16h22 · 11-20-2012, 06:55 PM

Reason i'm asking is during my last session at the track over the weekend at Autoclub Speedway I was about out of gas and my car started cutting out, but only in 4th gear. It almost felt like the timing was getting pulled back or maybe like mentioned it switched to the Intelligent mode mapping for a few seconds. And this wasn't happening every time I was in 4th, but once a lap and in nearly the exact same spot which threw me off even more! There doesn't seem to be any mechanical issues. Unfortunately I wasn't data logging. The car was running extremely strong other than in those few moments and it hasn't re-occurred since. It's a stage 2 setup with Cobb's OTS stage 2 map.

the suicidal eggroll · 11-20-2012, 07:08 PM

I have never seen any evidence to suggest that the car uses the low fuel signal for anything other than illuminating the light.

99.9999% chance your cutting out problems are from starving the pickup while cornering with low fuel. Either autocross with more fuel in the tank (at least 1/2 tank), or install a surge tank and external pump.

ScubyPhilly · 11-20-2012, 07:17 PM

Quote:

Originally Posted by the suicidal eggroll

...99.9999% chance your cutting out problems are from starving the pickup while cornering with low fuel...

Exactly what I was thinking. Especially when I read, "[At] the same spot [of the track.]"

b16h22 · 11-20-2012, 07:26 PM

this was on the road course and it was about 500-600ft i'd say after a very hard turn (turn 9) so you guys might be right. actually i'm hoping you're right!

11-19-2012, 01:13 AM	#1
b16h22 Scooby Newbie Member#: 90824 Join Date: Jul 2005 Location: CA Vehicle: 2009 STI	Does low fuel indicator adjust ecu? When the low fuel light comes on does it in any way adjust the ecu to compensate?

11-20-2012, 06:55 PM	#7
b16h22 Scooby Newbie Member#: 90824 Join Date: Jul 2005 Location: CA Vehicle: 2009 STI	Reason i'm asking is during my last session at the track over the weekend at Autoclub Speedway I was about out of gas and my car started cutting out, but only in 4th gear. It almost felt like the timing was getting pulled back or maybe like mentioned it switched to the Intelligent mode mapping for a few seconds. And this wasn't happening every time I was in 4th, but once a lap and in nearly the exact same spot which threw me off even more! There doesn't seem to be any mechanical issues. Unfortunately I wasn't data logging. The car was running extremely strong other than in those few moments and it hasn't re-occurred since. It's a stage 2 setup with Cobb's OTS stage 2 map. Last edited by b16h22; 11-20-2012 at 07:09 PM.

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11-19-2012, 01:26 AM	#2
Uncle Scotty NASIOC Supporter Member#: 16200 Join Date: Mar 2002 Vehicle: OK Houston we have an Uncle	mmmmm...good question...first time ive seen it in years

11-19-2012, 08:07 AM	#3
talvai Scooby Specialist Member#: 136358 Join Date: Jan 2007 Chapter/Region: NESIC Location: Newington, CT Vehicle: 2006 WRX Limited 6mt/5x114/vf43/S204	Not sure with older models but 08+ don't see why not. You guys have Si drive which adjusts throttle response, etc. Don't see why when light comes on you send a signal to ecu to change SI drive to another map. Not to sound like a douche but why? Why not just put gas before you get that low? Just saying.

11-19-2012, 09:39 AM	#4
ringlander Scooby Newbie Member#: 336100 Join Date: Oct 2012 Chapter/Region: Tri-State Location: nj Vehicle: 2011 sti	Realistically i don't think it would and here is why. That anti slouch feature which keeps the fuel gauge from bouncing all over the place, would affect it. The gauge is a median, an average of the high and low point of fuel in the tank and if they did have something like that it would be baaed on pressure not level . Also if your fuel pump was going bad, it doesn't change the map it blows up your motor. And lastly its called a dummy light for a reason. These are not facts just general knowing how they engineer cars.

11-19-2012, 06:58 PM	#6
imma_stocker Scooby Specialist Member#: 97043 Join Date: Sep 2005 Chapter/Region: TXIC Location: Tomballer Vehicle: 08 STI - 02 Z28 07 GSXR - 96 CBR	Rumor is the ecu trims back full boost psi around 1/4 tank. No clue if that's true or not, only digging into FACTORY ECU map will tell you. And that's how stupid rumors stay alive!

11-20-2012, 07:08 PM	#8
the suicidal eggroll NASIOC Supporter Member#: 51961 Join Date: Jan 2004 Chapter/Region: RMIC Location: Broomfield, CO Vehicle: 2005 STi 2012 WRX	I have never seen any evidence to suggest that the car uses the low fuel signal for anything other than illuminating the light. 99.9999% chance your cutting out problems are from starving the pickup while cornering with low fuel. Either autocross with more fuel in the tank (at least 1/2 tank), or install a surge tank and external pump.

11-20-2012, 07:26 PM	#10
b16h22 Scooby Newbie Member#: 90824 Join Date: Jul 2005 Location: CA Vehicle: 2009 STI	this was on the road course and it was about 500-600ft i'd say after a very hard turn (turn 9) so you guys might be right. actually i'm hoping you're right!