

| Subject: | Re: David Marshal. Why did this mod increase my fuel economy? |
| From: | David Marshall |
| Date: | Mon, 27 Mar 2000 22:07:50 -0800 |
I would say the statement of the engine gets more air and things get leaned out would be un-true in this case. CIS as you may already know is a very precise metering system. If anything the engine would see a richer mixture at full throttle due to the vacuum operated Audi 5000 warm-up regulator. A mixture of 1.5% is well within spec of a plain jane CIS system and is just slightly richer than the happy 14.7:1 air:fuel ratio which is a happy medium between economy and power. A value of 1.5% CO brings you just shy of the 12.5:1 ratio for maximum power, this also brings the Hydro Carbons up, which is what the smog police don't want to see. The value of 1.5% is the factory spec for the 1979 Audi Fox (manual) that the fuel distributor came from. On the post script, I have yet to see a 4 cylinder to 5 cylinder adaption plate for the Audi 5000s. I would dig into the Audi 4000 bin and take the bellhousing and flywheel from a mid 80s 4 cylinder - *should* be a bolt up - the flywheel is the only really big concern here. At 11:42 PM 27/03/2000 EST, Michael Modl wrote: >In a message dated 3/27/00 6:16:28 AM Pacific Standard Time, >lindgre@ONLINE.NO writes: > ><< So, why did things get better with a throttle that opens quicker? Not >that > > I am complaining! >> > >Simple. You have the CO set at 1.5, which is too rich. It should be around .4 >CO at idle. That is what a lambda ECU would hold it at if you had a O2 sensor >in your fuel injection system. Who knows what your CO is at cruising speeds, >probably higher. Your car WAS simply running too rich. Now you have the extra >air that it needs requiring less throttle for more power. See ya, Michael > 87 quattro > 87 syncro > >PS, David, is there an adapter plate for TDI engine to mate up to an Audi >Quattro 5000 5 speed trans. I'm assuming there is if an inline 4 will bolt up >to a vanagon transmission and with the 5 cyl conversion kit available with an >adapter plate to bolt the 5 cyl to the vanagon trans. What are your thoughts? > Thanks. > > -- David Marshall - - Quesnel, BC, Canada -- -- 78 VW Rabbit, 80 VW Caddy, 84 VW Westie, 85 VW Cabriolet -- -- 87 Audi 5000 Quattro, 88 2.0L VW Syncro Double Cab -- -- David's Volkswagen Home Page http://www.volkswagen.org -- -- Fast Forward Autobahn Sport Tuning http://www.fastforward.ca -- -- david@volkswagen.org (pmail) or vanagon@volkswagen.org (list) --
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