jpw@cbuxc.UUCP (Mike Vehonsky) (01/09/86)
*** REPLACE THIS LINE WITH YOUR MESSAGE *** Many new cars are advertising different types of fuel injection; multi-port, throttle-body, etc. Would anyone care to give a short tutorial on fuel injection in general, and how if any these 'variants' differ from REAL fuel injection? Or are they just names dreamed up by a marketing dept. Thanks In Advance, Mike Vehonsky
ahs@burl.UUCP (Spinks Albert H. ) (01/11/86)
> *** REPLACE THIS LINE WITH YOUR MESSAGE *** > > Many new cars are advertising different types of fuel injection; multi-port, > throttle-body, etc. Would anyone care to give a short tutorial on fuel > injection in general, and how if any these 'variants' differ from REAL > fuel injection? Or are they just names dreamed up by a marketing dept. > > Thanks In Advance, > > Mike Vehonsky *** REPLACE THIS LINE WITH YOUR MESSAGE *** I recently took a look at new cars and found displayed prominantly on the back of some of the small Chevrolets "Electronically Fuel Injection." When the time came to look under the hood, I tried to find the pipes that inject the fuel into the combustion chamber. No luck. I asked the salesman about it. He couldn't explain the discrepiency, a common failing among salesmen. Finally at the third sales lot I visited, the salesman took the carberator air cleaner off and showed me a small mechanism at the top of the carberator with two wires running to it for electronic control. According to the salesman, this allowed a computer to pulse the gas at the ideal rate for each operating condition. The experience turned me off. First I felt the manufacturer was misusing the term Fuel Injection. He is using a 'buzz word' that will make some people think they are getting something they are not. And second, I view it as being just another gadget to give problems. We are really getting too many things on car motors lately that lower the reliability and 'shade-tree' maintainability. One item of contention is the motor computer. As much as I use and respect computers, I don't care about having one under the hood of my car. I don't feel the advantages will outway the aggravation. -- Albert H. Spinks
rickb@tekig4.UUCP (Rick Bensene) (01/15/86)
> Many new cars are advertising different types of fuel injection; multi-port, > throttle-body, etc. Would anyone care to give a short tutorial on fuel > injection in general, and how if any these 'variants' differ from REAL > fuel injection? Or are they just names dreamed up by a marketing dept. > Thanks In Advance, > Mike Vehonsky While I'm certainly not an expert in the field, I think I can shed a little light on this. Tuned-Port-Injection: This is used on the Chevy Corvettes and IROC Z/28's and specially equipped Z/28's. It involves 8 individual injectors which inject fuel into the intake manifold runner just before the intake port of the head. The 'tuned port' comes from the curved tuned-length intake tubes which supposedly help increase bottom and mid-range torque. Throttle-Body Injection. This uses carburetor-like throttle bodies which have injectors in them. They sit on top of an intake manifold much like a carburetor, but have computer-controlled injector(s) in them which spray the fuel and mix it with the air. Used on early 80's Corvettes & Z/28 Camaros (with two throttle bodies), and many newer 4-cylinder applications. Multi-Point FI: Much like the Tuned-Port system mentioned above, minus the 'tuned-port' intake. Individual injectors feed the intake ports of the heads. On some systems, there are more than one cylinder served by each injector. All of the above systems are controlled by engine control computer, which monitors engine RPM, load, throttle position, air/fuel mixture, engine temperature, mass airflow, and other parameters to determine optimal fuel mixture. Most injectors are controlled by a pulse-width modulation system. The longer the pulse width applied to the injector, the more fuel is delivered. The computer determines the proper pulse widths, and sends pulses to the injectors to control the mixture. Some of the more sophisticated systems control the pulse width to each individual injector, based on the demands of each cylinder, while others compute one pulse width, and run the engine through one cycle before updating it, running all of the injectors with the same pulsewidth. Hope this is of some help. Rick Bensene {ihnp4, decvax, allegra, cbosg, ucbvax}!tektronix!tekig4!rickb Phone: Weekdays (503) 627-3559 BBS: (503) 254-0458 300/1200 baud, 24 hours a day US Mail: Tektronix, Inc. - P.O. Box 500, Mail Stop 39-170 - Beaverton, Oregon 97077
jimv@apollo.uucp (James Vienneau) (01/15/86)
> maintainability. One item of contention is the motor computer. As much > as I use and respect computers, I don't care about having one under the > hood of my car. I don't feel the advantages will outway the aggravation. That may be, however these controls are required for the manufacturers to meet the corporate fuel economy guidelines imposed by uncle sam. If you take the time to really understand how they work and how to debug them, they're really quite simple.
eli@cvl.UUCP (Eli Liang) (01/20/86)
For anyone out there who knows the differences between the many kinds of
fuel injection (cross-fire, multi-port, tuned-port, etc.), how about explain-
ing the differences between them and the advantages and disadvantages of
each. With so many cars being fuel injected these days, it would be nice to
know something about it. Thanks.
--
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Eli Liang ---
University of Maryland Computer Vision Lab, (301) 454-4526
ARPA: eli@cvl, eli@lemuria, eli@asgard, eli@mit-mc, eli@mit-prep
CSNET: eli@cvl UUCP: {seismo,allegra,brl-bmd}!umcp-cs!cvl!elithoth@tellab3.UUCP (Marcus Hall) (01/20/86)
In article <459@tekig4.UUCP> rickb@tekig4.UUCP (Rick Bensene) writes: >> Many new cars are advertising different types of fuel injection; multi-port, >> throttle-body, etc. Would anyone care to give a short tutorial on fuel >> injection in general, and how if any these 'variants' differ from REAL >> fuel injection? Or are they just names dreamed up by a marketing dept. >> Thanks In Advance, >> Mike Vehonsky > >Multi-Point FI: Much like the Tuned-Port system mentioned above, minus >the 'tuned-port' intake. Individual injectors feed the intake ports >of the heads. On some systems, there are more than one cylinder >served by each injector. > My Fiero V6 has multi-port fuel injection and tuned induction. The injectors are wired in two circuits with three injectors each. This means that the injectors fire three times for each engine cycle. I don't know why this is done except to minimize the complexity of the computer control, I guess. I would suppose that sequential-port injection would actually have seperate circuits for each injector and they would be fired only once per cycle. At any rate, I believe that multi-port injection means that the injectors are fired in groups, and sequential-port means that they are fired one at a time. I await any corrections.. marcus hall ..!ihnp4!tellab1!tellab2!thoth p.s. Does anyone know the REAL reason why multi-port injection is used? It seems that injecting gas at any time other than the intake stroke implies that the mixture cannot be controlled as well. How possible is it to convert a multi-port system into a sequential-port system? (probably not very :-()