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Old 04-15-2009, 02:20 PM   #4 (permalink)
Christ
Moderate your Moderation.
 
Join Date: Nov 2008
Location: Troy, Pa.
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Pasta - '96 Volkswagen Passat TDi
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Quote:
Originally Posted by hummingbird View Post
Thanks for the reply, Christ! I have two points here -

1. With increase in temp I saw a decrease in FE. Should it not be the other way round?

2. The ECU mistook my ~88 octane fuel to be 93, and gave me waay higher FE. What did it do differently with that assumption that it adjusted for the later tanks? (If I know, I can mimic it, so I get back the FE)
1. Again, this deals with more things than just intake air temperature. Specific density of the air, dynamic compression ratio in the engine, etc - all affect detonation characteristics. Without more information, I can't say for sure, or even in thought, that higher intake temp would actually increase your efficiency.

2. The ECU may have kept telling the engine to run at higher timing specs, in a more efficient range than the ~88 octane fuel could normally be run at according to the ECU's programming.

This is about as much as I can tell you specifically... hopefully, someone who knows more about your specific vehicle can chime in.
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