Engine control general question......
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Joined: Sep 2004
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Engine control general question......
Hello all, had a question for any engine control technicians out there. Wanted to know how to use and understand the Long and short term fuel readings. Just bought the "Modis" scanner and I am preparing to take the ASE L1 test in November. Havent worked on a car since 2000, but hopefully I havent been away too long...
Thanks again...
Ed
Thanks again...
Ed
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Joined: Sep 2004
Posts: 4
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The fuel trim is the change (positive or negative) of the amount of fuel the ECU is putting into the engine. For instance, +5% means it is giving 5% more fuel than the normal fuel trim map that the ECU comes with. The short term and long term parts are self explanatory. Short term means the here and now, how much the fuel maps are being modified right now. Long term is like an average of the short term over a certain period of time. If it bounces between 5% and 7% on the short term, the long term will be like 6%.
Thread Starter
Newbie
Joined: Sep 2004
Posts: 4
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Basic Engine control question.......
Thanks again, so the short term and long term fuel trim are basically a way to "see" how the engine is using fuel. To see a "positive" reading in short term would mean a "more" rich situation and looking at the long term would average the short term reading. So I would use this reading in relation to O2 sensor graphs and fuel injector pulse width to see if there are any abnormalities with fuel metering/managment? 
Ed
Ed
Last edited by Edclk430; Sep 20, 2004 at 05:32 PM. Reason: Forgot to insert text response....
