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  #1  
Old 12-04-2008, 02:01 AM
legacyau legacyau is offline
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injector duty cycle

Heres A question for the technically minded, does the ecu cut fuel on a trailing throttle eg down a hill if the throttle is closed ? i know my manual 4 cyl subaru does but do the svx do this? i am curious as to why we get such poor fuel economy around town
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Old 12-04-2008, 09:01 AM
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longassname longassname is offline
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Re: injector duty cycle

yes the ecu cuts fuel during engine braking. If the engine is not coupled to the wheels it needs fuel and spark to maintain idle.

If you get very poor around town fuel economy it is because of the condition of your car. The ecu with the oe programming uses the knock sensors to add in ignition advance. If your compression is low and or your knock sensors aren't good you end up driving around with less than optimal ignition advance and less than optimal power and fuel economy. Bad temp sensors also cause poor fuel economy--so do bad oxygen sensors--so does an inoperative egr.

Check your sensors and check your compression. Replace any bad sensors and if your compression is low put in hotter ngk plugs with platinum chips on the ground strap, pfr5b-11 or ifr5e-11. Keep your eyes open on the feedback on the new ECUtune Stage1Av1 software; you might want to consider getting it in addition to the above.
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Old 12-04-2008, 02:25 PM
legacyau legacyau is offline
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Re: injector duty cycle

When i say poor fuel economy, mine is getting approx 20 miles per us gallon around town is this average?
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Old 12-04-2008, 03:11 PM
1986nate 1986nate is offline
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Re: injector duty cycle

Quote:
Originally Posted by legacyau View Post
When i say poor fuel economy, mine is getting approx 20 miles per us gallon around town is this average?
That is actually pretty good for city driving. Some people I've seen are lucky to get 15 and its rated for 17 mpg city. Before my trans blew I was averaging 22 with about 50/50 driving.
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