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On 24 Feb 2006 at 20:46, Elroyyy@aol.com wrote: > She's a 1973 FI MT Squareback. > I ran the tune up; it consisted of an oil change, valve adjustment, plugs, > points and condenser, adjust timing, check idle. This was not my first tune up. > Everything was great for a little more than a week and then she began to run > rough. At first, she just wanted her accelerator pedal feathered at the light > to keep the RPMs up. A little later, she wanted the pedal tickled to keep from > stalling. Eventually she would stall and I'd have to crank her over and over > until she'd catch, blow petrol-smelling smoke, then continue. > Since I'm an avid reader of the type 3 list, I knew immediately that if the > car runs rich it must be a problem with the Voltage Regulator of the Cold Start > Valve. I ruled out the CSV because I live in Southern California and the > problem doesn't happen until after the car has been started. > So I connected my trusty VOM to the battery and got 12V. As the car > approached medium RPMs, the VOM began to read higher and higher and leveled off just > shy of 14V. But that's what it's supposed to read! The Voltage Regulator is not > my problem. Make sure that the CSV wiring between the CSV and the temp switch has not gotten shorted to ground. This can mimic cold weather. The best way to eliminate the CSV as part of the problem would be to just unplug it temporarily, as a test. It's possible that your VR only goes bad as it warms up, so try to take the car for a drive and then check the voltage after the drive. > Checked the fuel pressure - 29 (I like to split the 28-30 right down the > middle). Sounds fine. > He tested a known-to-be-good Pressure Sensor and nothing changed. He cleaned > the trigger points and nothing changed. He retested for spark -- it's fine all > around. Is there any chance that the PS on this car is the wrong one. The one for 70-1 has a couple of vent holes in the "cover" and these indicate a style of PS which has a brass diaphram which can crack and leak. The 72-3 PS came with a black cap over the adjustment screw, but sometimes these have been broken off to tamper with that screw. You really want one which hasn't been tampered with. Check the dwell and timing with a dwell meter and timing light? > But he discover that the injectors for 1 and 3 were spraying too much fuel on > each impulse. This is particularly troubling because the paired injectors are > 1&4 and 2&3. The injector wires were reversed on each side and 2 and 4 > started shooting too much fuel while 1 and 3 were fine. This tells me that it's not > a problem with the injectors themselves. Yes, sounds weird. How did you tell this? It's hard to see this visually, did he actually measure it? If this is true, I agree that it sounds like a brain problem, but such problems are actually exceedingly rare. Were these injectors all genuine Bosch? > Next, he called to ask if I had another ECU we could try. The short answer is > no. She's a 73 with an "E" system (brain, pressure sensor and throttle valve > switch all match). The only ECUs I have are a "D" and a blank. There is no > part number anywhere on the blank. So we tried them both. > The "D" brain didn't seem to affect anything. The blank, however, was another > story altogether. Instead of pushing out too much fuel, this brain allows no > fuel to 1 and 3 while she idles. But when she gets a little gas, she'll run > fine on all four. > > Personally, I don't think the problem lies within the ECU. But I'm open > minded enough to consider it as a possibility. I have a spare "E" ECU on the way > but it won't arrive until some time next week. Anybody have any ideas? I also have E brains here. I assume you checked the hose between the intake air distributor and the pressure sensor, just to make sure it hadn't fallen off. -- ******************************* Jim Adney, jadney@vwtype3.org Madison, Wisconsin, USA ******************************* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ List info at http://www.vwtype3.org/list | mailto:gregm@vwtype3.org ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~