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Originally Posted by tasdrouille
Hey Jojo, great post.
Off course we want to know how to do this mod.
Can you get fuel consumption (l/h) in group 015 and speed in group 018 in VAG-COM? I know I could on both my A3 and A4, but both were OBD-II.
With logging and using markers in VAG-COM while making a couple of highway runs in a loop using your cruise control, it should be pretty easy to test this. You just plot the fuel consumption lines on a graph after the fact and see which configuration gets the best mpg.
I did that when I tried various IQ, boost and timing mods with my A3.
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Mod is super simple, the stock air box has 2 inlets and a flapper valve to switch between them. CAI goes out the front and into the fender well, WAI goes out the back (smaller diameter opening) through the stock warm up hose to the heat shield on the exhaust manifold, which comes stock this way. The flapper valve is controlled by a temperature sensitive vacuum switch (mechanical) which is mounted in the air box itself, vacuum lines connect externally. I simply removed the vacuum feed from the vacuum switch and ran it directly to the flapper, or basically just remove both vacuum hoses from the switch and hook them together, thus eliminating the switch. Now you have manifold vacuum controlling the flapper directly. Strong vacuum equals WAI/HAI and low vacuum opens the flapper for a burst of CAI. Just a quick jab of the throttle makes the flapper move, hard to tell what it does while in motion however, but judging by my numbers I would say I am getting the warm/hot air I was trying to get.
Phase 2 is to find an electrically controled vacuum switch so that I can override this behavior and force it into CAI mode if things heat up too much. Know of any electric/vacuum doo dads that can do this in a A3 Jetta, as I do have a parts car I can steal things from :-) Maybe the charcoal canister purge valve or something, not 100% sure yet, but I am sure there is one in there somewhere I can steal for phase 2 of this mod.
I have a lot less groups available to me being OBDI, but I will check it out to see what data I can log. I don't recall seeing fuel consumption though. I know I can get VSS input and injection pulse width, and I don't care if it is real time display or I just hack away at my log files after the ride to see the mpg numbers at any given point in my ride, you know? I will be doing my logging on my long commute to and from work daily, so same ride to and from with lots of different scenarios along the way. Other than that just about all inputs to the ECU can be logged. Just a matter of figuring out which ones I need to calculate the MPG along the way, you know?
JoJo