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On 25 Aug 2005 at 8:34, Craig Webb wrote: > I've got both a 72 type 3 and 72 type four unit. The injectors are the same > for both (not sure if that's right for the type four 1.7, but the injectors > are the same number as the type three). I've already run a type four > pressure sensor on the type three set up and it didn't make a huge > difference. Throttle body is perhaps just slightly larger dia. Not checked > the throttle switch yet. I just checked the injectors and you're right, they're the same. I didn't realize that. For some reason the 914 valves are different; that may just be the funny little right-angle hoses they come with. It won't matter which TVS you use, as long as it has the right number of terminals for the wiring harness you have and the brain you're using. > I'm running about 34psi (as long as my gauge is accurate!) Fuel pump is a > brand new NOS item with new filters. Fuel pressure stays good whilst revving > when stationary. There's no load when stationary, so that's no real test. It sounds like you've covered most of the bases, but I'd still run a gauge into the car and test the pressure on the road. The screen in the tank could be clogged. > My main bible is an innovate motorsports LM-1 unit with a wide band > sensor plugged into the exhaust. I'm currently running rich at idle > and low speeds (12:1 afr). When I get up to speed I'm slightly lean > at 15.2:1. I was holding out fiddling with the pressure sensor until > the last resort. I thought I would try the type four ECU as its > closer to my engine size, plus its got the idle pot. If I can > transplant this, I may need just a tiny amount of tweaking on the MPS. > I would also like to bring that fuel pressure down some to 30ish. I'm not familiar with that sensor, but it sounds like you're being thorough. The first thing I would try would be 34 psi with the type 3 PS and brain, from the same year as the type 3 wiring harness and throttle valve switch. I'm surprised that 34 psi is maxed out. I thought they would go much higher than that. The important point to consider here is that the throttle body is an essential part of the FI system. The PS is calibrated to measure the pressure drop that occurs across the throttle valve. With the wrong throttle valve, the brain won't calculate the right amount of fuel. 1776 is only an increase of 11% over the stock displacement. I'm guessing that the stock PS has enough headroom to tolerate that, but with your instrumentation you should be able to tell us, without guessing. I think we're all interested in how this turns out. -- ******************************* Jim Adney, jadney@vwtype3.org Madison, Wisconsin, USA ******************************* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ List info at http://www.vwtype3.org/list | mailto:gregm@vwtype3.org ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~