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On 28 Jul 2001, at 1:11, Shirleyclan wrote: > I am stumped. I have a 72 Squareback built in June 72 but the wiring > harness and FI match the diagrams for August 72 and later. There is a > plug next to the pressure sensor with 2 wires numbered 41 and 42. they > don't show in any wiring diagrams I can find, including the Bentley > manual. I think it may be associated with my FI. A FI manual I have > (plus additional book) indicate the August 72 (and later), plus 73 ECU > 311-906-021E (black color code) were built with a potentiometer on the > ECU to adjust CO admissions. Sounded like a great deal to me then I > checked my ECU. The ECU has the correct PN (no black marking?) but no > CO potentiometer on the outside. Since my car seamed to be built > during the gray area of a production year (model year shift), I can't find 41 or 42 on any of my literature either, but I suspect that they are the 2 wires that plug into the little air valve that disables the vacuum advance except in high gear. This was a 72-only "feature." I disconnect them and run the vacuum advance in all gears. My diagrams show these wires, but don't put numbers on them. If these wires end in a little oval connector that is different from all the other FI connectors, then that's what this wire is for. > I turned to the INTERNET found a good FI troubleshooting site > http://www.estinc.com/porsche/djet.html and low and behold I found > that some of the late 72's were built with the potentiometer next > to the pressure sensor > http://www.geocities.com/MotorCity/Shop/4123/Potent.html (PN 311 > 906 019). This is one of those things that gets repeated so often that everyone starts to believe it and repeat it as true. Here are the facts: No type 3 ECUs ever came with this adjustment, although some type 4s did. Some of my aftermarked manuals have pictures claiming to show a type 3 brain with the pot on it, but if you take a look at how the brain is mounted you will quickly see that it is the type 4 mounting, not the type 3. I don't know what that part # is, but it's not a brain because all the brains will have the same first 9 digits and only the suffix letter changes. - ******************************* Jim Adney, jadney@vwtype3.org Madison, Wisconsin, USA ******************************* ------------------------------------------------------------------- Too much? Digest! mailto:type3-d-request@vwtype3.org Subj=subscribe