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On Wed, 28 May 1997, Shannon wrote: > >his former owner felt the same as i do about fuel injection.......it sucks. > > I have heard this a lot...when the FI works it's great...when it doesn't > it's al living nightmare. And I believe it too because I had all kinds of > heartache with my 70's FI system. In my opinion, if you can use a multimeter & read a fuel pressure gauge, fuel injection is no more difficult to work with than a carburetor. In fact, in some ways a carb is equivalently complex. The basic design concept of a carburetor is inherently flawed, since the amount of fuel drawn for a given amount of air taken is varies with the air speed. Much of a carb's design is a bunch of features--bandaids, workarounds-- that attempt to correct for this behavior. This is the source of its relative complexity, IMHO. What carbs *do* have going for them is that lots more people have worked with many carburetors for many, many decades (over a century, eh?) and so the body of practical knowledge re: carbs is much more widely spread. > Are there any special maintenence tips to keep your FI system alive? Any > fuel additives that you fellow T3'er swear by? I think that studying up on D-Jetronic fuel injection is the absolute best thing one can do for their injected T3. I highly recommend "How to Tune and Modify Bosch Fuel Injection," but read everything you can get your hands on. I had *lots* of problems with my fuel injection when I first got my squareback. The first problem was one of my own: "if anything goes wrong with the injection, I'm throwing on carbs!" My injection system caused my car to crap out once, and I was ready to lay down the cash for a traditional induction system. But guess what? My so-called (by me) "injection" problem was an ignition problem. It had *nothing* to do with the injection. See, the f.i. was a big mystery, so any difficulties I had with the car I immediately chalked up to the injection system. My next few "injection" problems also had nothing to do with the fuel injection!!! Now, I'm not saying that it's perfect, and I have had difficulties. If you swap to carbs, you're trading one set of failure modes for another... know anybody who's had trouble sync'ing dual carbs? Stuck float? Wrong jet? D-Jet really isn't that bad. I wonder if anybody can honestly say both "I understand f.i. as well as or better than carbs" AND "I hands-down prefer carburetion." If you are well versed in carbs, guess what? D-Jet has a system that performs virtually every funcion in the carb, conceptually speaking. Check it out: choke = temp sensors fast idle cam = aux. air regulator accel. pump = throttle position sensor pumping accel. on a cold day = cold start valve etc. Many of the D-Jet components don't play a heavy role in steady cruising; they just augment performance under extraordinary circumstances (e.g. very cold temps, starting, punching the gas pedal). Here's what's left at the heart of the system: injectors: they open & close to squirt gas behind the intake valve. When more gas is needed, they stay open a bit longer each time they pulse. trigger points in distributor: there are two of them; when one opens it causes one pair of injectors to fire, when the other opens it causes the other pair of injectors to fire. manifold pressure sensor: a crude (but more efficient than carb!) measure of the amount of air entering the engine. That's really it, folks. The brain looks at a combination of inputs to determine the length of time the injectors are open, but that's about it. Cold out? Hold the injectors open a bit longer--gives more gas like a choked carb. High manifold vacuum because butterfly is closed? Must be idling or on decel; shorten injector duration. I think that D-Jet also suffers from the old guess-replace-repeat repair philosophy: "I guess that X is the problem, so let's replace X." Doesn't fix the car? Guess again: "Maybe it's Y; let's try that." This can get very expensive very quickly! I would caution folks to not pay to replace any f.i. component unless it is confirmed to be faulty via electric or other tests. I also understand that if, say, somebody has a bad brain, a clogged injector, worn distributor shaft *and* a bad pressure sensor, the carb swap may save you lots of dough. My personal insurance against such a situation is the collection of f.i. spare parts. People practically (or literally) *give* them away in many cases! Try low-balling at swap meets on f.i. parts; you'll come away with loads of spares. It took me a *long* time to try to be rational about my injection system, and it still takes diligence for me to stay rational when there are mysterious problems. If you're having D-Jet difficulties, grab a book--or a couple of books, like "Tune & Modify" and the Idiot book-- and have at it, slowly & carefully. ...and if you decide to pitch your f.i., drop me a line & I'll give you my shipping address. I'll even pay the postage. :) Peace, -Greg '71 squareback '63 Beetle