car economy question - Page 2 - SV650.org

maviczap · 07-09-09, 04:24 PM

Get the man round with his diagnostic tools then

07-09-09, 04:39 PM

Exhaust could be playing a big part in it. Get that sorted then take it from there.

07-09-09, 05:01 PM

put it in neutral and roll on down hill sections of road

07-09-09, 06:58 PM

Surprising fact f/i--A car uses more fuel rolling down hill in neutral with the engine running than in a high gear with the throttle closed. Basic explanation-- throttle close in gear delivers no fuel to the engine as the vehicle is using the gearing to control the speed and turn over the engine--Whilst in neutral the engine has to be kept running so the ECU delivers a fixed amount of fuel to maintain engine speed.

As you have said you have been having trouble with the ECU and the problem was at the beginning of your journey it is possibly a heat sensing problem delivering to much fuel. This could be a simple thermostat[water] problem or one or more of the engine ECU sensors
You have said it is a 1.4 but what car and model? This would help as certain types of vehicles have repetitive fault traits

Wideboy · 07-09-09, 08:43 PM

astra/G mk4 1.4ls

Bri w · 07-09-09, 09:46 PM

Bearing in mind its early in the journey, automatic choke?

08-09-09, 07:00 AM

the exhaust could be playing a big part...

IF, the baffles are collapsing the gasses will not be flowing properly, the lamda sensort (assuming it has one) wont be reading correctly thus messing up fuel air ratios.

I wouldn't say its a long shot, but you haven't told us what you normally get to the gallon, if its 30, then tyres or exhaust if you used to get 45 then its something worse i reckon.

when my Renaults cat collapsed my mpg dropped from 32 to 14mpg in two days.

08-09-09, 08:14 AM

Quote:

Originally Posted by kwak zzr

put it in neutral and roll on down hill sections of road

Ah the clutch and roll game - me and the missus try to out-do each other in clutch and roll distances! I usually win as my car is heavier!

Biker Biggles · 08-09-09, 10:58 AM

Ive never known a fuel guage to be anywhere near accurate enough to measure fuel consumption.The only way is to brim the tank,zero the trip, and drive for a couple of hundred miles and brim it again.Then do the arithmatic.

08-09-09, 11:11 AM

Quote:

Originally Posted by Biker Biggles

Ive never known a fuel guage to be anywhere near accurate enough to measure fuel consumption.The only way is to brim the tank,zero the trip, and drive for a couple of hundred miles and brim it again.Then do the arithmatic.

Or use the on-board computer as thats a constant algorithm

07-09-09, 04:24 PM	#11
maviczap Member Mega Poster Join Date: Mar 2007 Posts: 9,097	Re: car economy question Get the man round with his diagnostic tools then __________________ We're riding out tonight to case the promised land Make everyday count RIP Reeder - Jolly Green Giant and comedy genius

07-09-09, 04:39 PM	#12
svdemon Guest Posts: n/a	Re: car economy question Exhaust could be playing a big part in it. Get that sorted then take it from there.

07-09-09, 05:01 PM	#13
kwak zzr Guest Posts: n/a	Re: car economy question put it in neutral and roll on down hill sections of road

07-09-09, 06:58 PM	#14
Dicky Ticker Guest Posts: n/a	Re: car economy question Surprising fact f/i--A car uses more fuel rolling down hill in neutral with the engine running than in a high gear with the throttle closed. Basic explanation-- throttle close in gear delivers no fuel to the engine as the vehicle is using the gearing to control the speed and turn over the engine--Whilst in neutral the engine has to be kept running so the ECU delivers a fixed amount of fuel to maintain engine speed. As you have said you have been having trouble with the ECU and the problem was at the beginning of your journey it is possibly a heat sensing problem delivering to much fuel. This could be a simple thermostat[water] problem or one or more of the engine ECU sensors You have said it is a 1.4 but what car and model? This would help as certain types of vehicles have repetitive fault traits Last edited by Dicky Ticker; 07-09-09 at 07:00 PM.

07-09-09, 08:43 PM	#15
Wideboy Evel Knievel Mega Poster Join Date: Jun 2007 Location: Eastleigh Posts: 4,641	Re: car economy question astra/G mk4 1.4ls __________________ 05 DRZ400E RIP hovis

07-09-09, 09:46 PM	#16
Bri w Member Join Date: Jun 2009 Location: Turre, Almeria Posts: 668	Re: car economy question Bearing in mind its early in the journey, automatic choke? __________________ *"It's not the years in your life, it's the life in your years."* Currently - Fighting the urge... seen a nice Triumph America Previously - Honda CB125, Honda CB400-4 & BSA B40, Moto Guzzi 850, Yamaha RD250, Suzuki GT380, Kawasaki Z1B, Kawasaki Z650, Honda VFR, Triumph Street Triple R.

08-09-09, 07:00 AM	#17
454697819 Guest Posts: n/a	Re: car economy question the exhaust could be playing a big part... IF, the baffles are collapsing the gasses will not be flowing properly, the lamda sensort (assuming it has one) wont be reading correctly thus messing up fuel air ratios. I wouldn't say its a long shot, but you haven't told us what you normally get to the gallon, if its 30, then tyres or exhaust if you used to get 45 then its something worse i reckon. when my Renaults cat collapsed my mpg dropped from 32 to 14mpg in two days.

08-09-09, 10:58 AM	#19
Biker Biggles Member Mega Poster Join Date: Jan 2005 Location: Barnet Herts Posts: 5,071	Re: car economy question Ive never known a fuel guage to be anywhere near accurate enough to measure fuel consumption.The only way is to brim the tank,zero the trip, and drive for a couple of hundred miles and brim it again.Then do the arithmatic. __________________ On a clear day we stand there and look further than the ordinary eye can see.

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