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You have the question on your throttle switch connection ? Also you have a question on your compression lowering using EFI. Do you have a four wire throttle valve switch ? Is your harness plug a four wire one for this ? Do you have a Bently Manual ? Turn to page 17, 18 and 19 . this shows the connections to each component and their connection to the " brain ". The connections will vary depending on the year. The switch on my car can be disconnected with little effect on the EFI system. The eariest year (1968 to 1969) throttle valve is installed to turn off fuel to the injectors or at least minimize it to prevent backfiring when removing the foot from the pedal or going down hill or in other words , high vacume conditions. The earliest has two wires (screwed in ) and they are pins 20 and pin 17 on the throttle valve switch (they are casted in the switch )to the same pins on the "brain" . The Brain is ver "A" or "B" (Part # 311 906 021 A or B) 1970 to 1972 The next version of EFI system is shown on page 18 in the EFI section. This version uses the brain known as the " C" brain (Part # 311 906 021 C ) and has the gas pedal pump feature incorporated that the last versions did not have. The throttle valve switch has four connections on it and has the pin numbers 9, 14, 17, and 20 casted on it and these go to the same pins on the "brain". This switch has two features now: the deceleration mixture control (prevents backring) and the pedal gas pump . The addition of the gas pump feature provides additional 25 injections per full throttle movements when throttle is at rest. This provides more gas when starting car (pumping gas pedal when engine has not started) and when accelerating faster when foot pedal is pressed in; just like a carburator acceleration pump feature. If you open this Switch you can see about 25 little connections that provide electromechanical control of the pump feature as well as electromechanical control of the antibackfire feature. 1973 (only one and last year) The latest version I am not fully familiar with since I do not have this brain. It should be the "D" brain (part number 311 906 021 D ) . I beleive this is an emission brain that has the exaust gas circulation valve relay incorporated to it . The Throttle valve switch has 5 connections ; 9, 14, 17, 20 and 47 which is ground. All connections go to the brain of the pins of the same number except pin 47 which is ground. These pins are casted in the switch. The features of this version are probably made for emissions control and may provide electronic control of the features of the last version instead of electromecanical. After said all of this, you should match your brain with the switch, if your brain is an older one , you should use the two connection switch and so on. It all depends on the brain style. The system will work with a disabled switch , at least in my system. My car is a 1969 and I set my car up with the throttle pump feature using a newer throttle valve switch and a " C " brain . I just wired it up like it should. If you need a different switch to match your brain and wiring just ask the list about one or you can buy a new one or find one in the junk yard like I did. You can find one in a pre 1975 luxery Mercedes with V8 or 1973 volvo with D-jectronic or all 70's Volvo with straight 6 cylinders; they have similar bosch switches to our cars. The wire connectors on these cars are similar to ours. All these items are available new at their respective dealerships. If you cannot find the plug or switch e-mail the list or me we can help you get one. you can get new connectors, pins, and plug from the dealership. I have gone thru this before. I hope I did not give you any incorrect information, the guys on the list should be able to straighten me out if my data has flaws. What version brain do you have ? ----Your compression question . Lowering compression will not affect your EFI operation at all in fact EFI can take compression modifications bettter than carbs. The recommended modification (my recommendation, other people on the list may not see it the same way as I see it) is to make your Pressure sensor adjustable to adapt it to your driving conditions and engine requirements. More the compression less gas is needed since you have more power with this engine setup. This system will tolerate a leaner fuel mixture since the fuel injected cools off the combustion during entry and is more denser than a carburated setup. A carburated setup when leaned up will cause damaging pre ignition to your engine but the EFI will not be pre ignite as easily unless the prewssure sensor is leaned excessively to the point that the engine shakes in idle. Leaning will give better gas mileage and run the engine a little warmer. ***When compression is lowered your EFI will adapt to it, your engine will be cooler but you will slightly lose power (just a little , sometimes you will not notice it, depending on how low you get it) I accidentally lowered it so much that I was running a compression of 75 lbs per cylinder for one year and to compensate to the lowered power, I richened the mixture by tweeking the adjustment on my modified pressure sensor. I ran this for one year. The deck height on my pistons to head clearance was over .01 in which was huge and worked perfectly. When I burned my heads when my brother disconnected the heaters from the fan shroud when he went to Arizona (he did not know how to turn off my heater), I lessened the deck hieght for more compression .008 in. What I am saying here , there is no problem affecting the EFI when nodifing the compression. If you wish to tweak it better (more zoom or better gas mileage) , you can make the pressure sensor adjustable. I can verse you on this, just ask . If you want additional zoooom on your car, I can suggest all sorts of things, kick ass gas mileage with pep. I hope I have helped you. LEON MARTINEZ 1969 SQUAREBACK EFI/AUTO SAN DIEGO AND TIJUANA ------------------------------------------------------------------- Unsubscribe? mailto:type3-request@vwtype3.org, Subject: unsubscribe