DIY_EFI Digest Saturday, 7 September 1996 Volume 01 : Number 264 In this issue: Intel Engine Control Overview Re: troubleshooting a taurus Re: Knock sensor spectrum? Re: Ancient History re: troubleshooting a taurus Re: Ancient History Re: Fuel on the intake valves New follower... water injection See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- From: cloud@xxx.edu (tom cloud) Date: Fri, 6 Sep 1996 16:41:18 -0500 Subject: Intel Engine Control Overview Intel has some interesting data on EFI on its web site. The following was taken from: http://www.intel.com/pressroom/archive/releases/engback.htm It's a lot of stuff -- I hope it doesn't cause anyone any problems. =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D Engine Control Overview=20 Press Backgrounder December 1995=20 B.C.--Before Microcontrollers It was probably inevitable, the application of computer technology to automobiles, and skyrocketing fuel prices due to the energy crisis certainly accelerated the process. But early engine controls were far from the sophisticated digital devices we use to day.=20 Electronic engine control first came to light in 1978 in what was called a "closed loop" carburetor. It was a response to the oil crisis and promised marginally better fuel economy. At the same time, national concern over airborne pollutants propelled inv estigation into the origins of automotive exhaust components, how pollutants were formed, and how they could be= abated.=20 Why electronic control? Gasoline-powered Otto cycle engines are simple. Combine measured amounts of air and fuel in a confined space and ignite them. The pressure of expanding gasses forces a piston to move. This motion is translated into rotational movement. Like all simple things, there's more than meets the eye.=20 In the 70's, engines relied on mechanically generated signals to ignite the fuel/air mixture. Electrical energy from a battery was stepped up from 12 volts to many thousand volts by a coil. A mechanical "distributor" selected the appropriate spark plug and sent a signal along a wire. That selection "window" was wide, the ignition signal (spark) could be initiated any time within many degrees of rotation as a "rotor" contacted mechanical switch points inside the distributor.=20 Science knew that the outcome of combustion--both power and pollutants--was greatly affected by how precisely the fuel/air mixture approached theoretical perfection and when the ignition event took place. To get clean air, fuel had to be precisely mixed i n a "stoichiometric" 14.7:1 ratio. The mixture had to be ignited at a precise instant that varied with load, speed,= and other factors. Mechanical devices could not achieve the required precision and automakers soon approached Intel, a manufacturer of mic rocomputers and microcontrollers. (A microcomputer chip with a single preprogrammed task is referred to as a microcontroller.)=20 Early discussions centered on sensor data~ what information an engine microcontroller would require. Critical needs included the rotational position of both crankshaft and camshaft, and air flow. Throttle position and rate of throttle position change (the transmission wants to know when you need to accelerate quickly) were needed, too.=20 Rotation sensors i.e, crankshaft, camshaft, and ABS sensors at the wheels utilize a wide variety of technologies. Optical sensors may use infrared Light Emitting Diodes to peer through a slotted wheel. Other sensor designs interpret the rise and fall of magnetic energy as a metallic part approaches and departs. Interestingly, many very precise sensors receive only 4 signals per 360~ of rotation--exact position is calculated mathematically, predicting not only position, but whether the engine is accelerat ing or decelerating. This accuracy allows the fuel/air mixture to be ignited at a precisely selected moment appropriate for engine power and emissions= control.=20 Other data signals are critical to powertrain control. The microcontroller has to know temperatures in the engine's water cooling system along with oil temperature and transmission temperature. Fuel injection requires knowing atmospheric density and how quickly air is being drawn into the intake manifold. Air temperature affects air density. Hydraulic pressure information is sent to the microcontroller by automatic transmissions, as are battery voltage, road speed, and oil pressure.=20 Every signal adds calculation complexity as it increases the precision of control.=20 Within the last five years engine microcontrollers have also been required to determine shift points as the industry installed electronically controlled (vs. hydraulic/mechanical) automatic transmissions. The precise management provided by digital control means every automatic transmission will soon be under numeric control.=20 As engine control advances, so does data complexity. Oxygen sensors enabled controllers to accurately mix air and fuel based on combustion results. Now, a second oxygen sensor placed down stream from the catalytic converter infers the state of the catalyt ic converter (e.g. converters work best when hot; they suffer contaminant damage, even aging.)=20 At one time it was thought that some kind of sensor would be added to each cylinder to monitor every combustion event. This would have added enormous cost and complexity to engines. Instead, by increasing the power of software--placing added burdens on th e engine computer/controller--events can be inferred or predicted. This increase in computational power places great demands on microcontroller performance.=20 Computer chip families or "architectures" may be understood by an analogy to a subdivision. Every house may look different, yet it is built from common components. And the core structure--placement of furnace, water and sewer--may be identical in every bu ilding. Computer chips are built the same way with a core framework embellished by appropriate structural add-ons. Consideration is given to growth (both in raw processing power and memory) and additional input (more sensor data links.) So a microcontroll er can add more memory or calculation power up to its architecture's limit, just as a growing family can add rooms or central air conditioning.=20 Into the 90s. Power and Memory. If controlling what happens in an engine and automatic transmission were not sufficient challenges, a greater one has emerged from legislation. Specifically, On Board Diagnostics II (second generation) laws. These require monitoring automotive systems th at affect emissions. Not only does your cars' engine control unit have to "watch" what goes on and record troubles for service technicians as they happen, OBD II rules require the prediction of deterioration of the following: catalytic converter, fuel de livery and evaporative emissions systems, crankshaft and camshaft position sensors, oxygen sensors, manifold air temperature sensor, ignition system and others.=20 Let's look at the most difficult problem, ignition misfire.=20 A four-cylinder engine cruising on the freeway at 65 mph revolves at approximately 3,200 revolutions per minute or 6400 spark events per minute. Because of moisture, voltage drop, or a variety of other factors, some misfire is inevitable. The engine micro controller monitors combustion and should, for instance, 6 of 20 sparks in a row fail in any one cylinder, the engine controller must notify the driver "SERVICE ENGINE SOON." But what if you splashed through a deep puddle and a damp wire caused a temporar y misfire?= =20 Sophisticated algorithms examine error data and query whether the event is recurring. If it was an isolated incident, as in our damp spark plug wire example above, the check engine light is extinguished.=20 This benefits the consumer. When a car arrives for service, modern computer-powered diagnostic equipment can directly interrogate the on-board microcontroller and elicit a specific response. This could enable the mechanic to go directly to, for instance, spark plug number 4 and begin= repair.=20 This sophisticated diagnostic power requires roughly the same computational capability as the engine controller itself.=20 Because of increasing complexity, responsibilities, and the sheer number of calculations, engine microcontrollers need increased power to avoid being overwhelmed. Just as desktop computers evolved from early 8088 PC Jr. machines into today's Pentium=AE processor powered models, so have engine microcontrollers changed.=20 The latest generation of microcontrollers, like Intel's 83C196EA, exemplify this vastly improved processing power and communications ability.=20 Up to Date Data Collection Microcontrollers utilize digital signals. Sensor data (voltage, temperature, linear and rotational velocities, etc.) must be converted from continuous or analog information into the digital form required by microcontrollers. This Analog-to-Digital convers ion is typically performed within the microcontroller.=20 Another critical need is the ability to capture and compare events as they happen. And high-speed input and output channels transport data to the microcontroller for action. The microprocessor core itself needs raw power and speed as it executes the complex instruction codes called algorithms.=20 Once sensors, algorithms and the microprocessor core have done their work, control signals are sent out to tell the engine what to do. High-speed channels specify when and how long to fire spark plugs, when and how long to send fuel through the injectors , or when to shift to a different gear. And there is a need to query sensors for updated data in return.=20 Intel's new 83C196EA microcontroller harmonizes with modern engine control needs. It has 16 Analog-to-Digital converter channels built in. Its new higher speed core zips along twice as fast--32 MHz vs. 16 MHz--as its predecessor. This kind of speed is optimum for power train control, particularly its high-speed I/O for controlling electronic transmissions. The family features 17 event capture-and-compare channels and eight capture-only channels for a total of 25 high-speed Input/Output channels.=20 Intel's history in engine control electronics is lengthy, from the first 1983 Ford EEC-IV based on the 8061 microcontroller to today's modern 8065 chip set, also known as the EEC-V. Today, Ford is still using the 8065 in many of their new vehicles produced through the start of the next decade. The 16-bit architectures, such as the 8065 and MCS=AE 96 controllers, have been widely accepted in Europe and the U.S in ABS, engine control, and networking applications. From the introduction of the 8061, Intel has continued to provide more innovative and highly integrated microcontrollers in order to help their customers with evolving powertrain applications. Specifically, the 83C196EA doubles the performance of our existing microcontrollers while adding more functionality. The 83C196EA will provide designers with lower development costs and time-to-market. ------------------------------ From: Ron Madurski Date: Fri, 6 Sep 1996 16:56:09 -0500 (CDT) Subject: Re: troubleshooting a taurus : : :Sorry if this is a bit off subject. : :A coworker has paid an insane sum to a dealer to fix a problem which :hasn't gone away - and I believe that it should be a simple EFI :problem. : :The taurus has a very hard time starting after sitting overnite or :over perhaps 8-10 hours. Takes a large amount of cranking with no :firing, then stumbles slowly to life. Ambient temperature doesn't :seem to have any effect. Computer reveals no fault codes, pump and :filter are good. : :Isn't there a fuel accumulator which should maintain fuel pressure :when sitting? If this was faulty would it allow pressure to drop - :forcing the pump to charge the system again before it could start? Yup and it's easy to check. Put a pressure gauge on the fueln line in and see if it drops while setting for awhile. : :Any insight would be appreciated : :TIA :-mike :mfahrion@xxx.com : - -- Ron Madurski rmadursk@xxx.com ------------------------------ From: cloud@xxx.edu (tom cloud) Date: Fri, 6 Sep 1996 17:14:04 -0500 Subject: Re: Knock sensor spectrum? >Tom, > >I'd appreciate a copy of the application note spra039.pdf if possible. > I've gotten a lot of requests for this -- it's taking up a lot of my mail handler's time. If you can, it can be obtained from: Sources: http://www.ti.com/sc/docs/psheets/appnote.htm You have to go through a couple of harmless gyrations to get a 'loser' name and password before it can be downloaded. You can ftp it from: ftp://efi332.eng.ohio-state.edu I put it in the 'incoming' directory, and it's not protected, so can be downloaded from there ... I suppose it will be put somewhere else (maybe 'pub' ??) in a little while. While you're there, check out the 'caldemo.zip' file which runs on 'real' computers (PC-comp / DOS) and is an example of an EEC-IV calibrator. Tom ------------------------------ From: "John Faubion" Date: Fri, 6 Sep 1996 17:18:24 -0500 Subject: Re: Ancient History > So, you're telling me these mpg figures don't bother you? > > Tom > Well Tom actually no they don't. You see I have a 78 El Camino with a 427 fat block. I built it quite mild to begin with and ran a Turbo 400 auto behind it with a 2.73 rear axle. With this combination I had an average of 12-14 mpg in town and 21+ on the highway. With a switch to 3.55:1 rear ratio, my in town mileage stepped up and my highway mileage dropped to 15-16 mpg. Next step is a 700-R4 so that I can get my highway mileage back. This is also using a QuadraJet 4bbl. With my EFI project I hope to improve both sets of mileage figures. John Faubion jfaubion@xxx.net ------------------------------ From: SRavet@xxx.com Date: Fri, 6 Sep 96 17:52:15 CDT Subject: re: troubleshooting a taurus "Mike Fahrion" Wrote: | | Sorry if this is a bit off subject. | | A coworker has paid an insane sum to a dealer to fix a problem which | hasn't gone away - and I believe that it should be a simple EFI | problem. | | The taurus has a very hard time starting after sitting overnite or | over perhaps 8-10 hours. Takes a large amount of cranking with no | firing, then stumbles slowly to life. Ambient temperature doesn't | seem to have any effect. Computer reveals no fault codes, pump and | filter are good. | | Isn't there a fuel accumulator which should maintain fuel pressure | when sitting? If this was faulty would it allow pressure to drop - | forcing the pump to charge the system again before it could start? | | Any insight would be appreciated Maybe a leaky injector causing the pressure to bleed off, but also flooding the engine? I wouldn't think it would take long for the pump to build up pressure, but if the engine is flooded it would take a few cranks to get the gas out. Sometimes the ECM recognizes a "clear flood" condition while cranking and the pedal is WOT. It doesn't inject any fuel, or very little, to allow the flood to clear. It should be simple enough to put a fuel pressure gauge on the fuel rail and see if it maintains pressure. - --steve | | TIA | -mike | mfahrion@xxx.com | Steve Ravet sravet@xxx.com Baby you're a genius when it comes to cooking up some chili sauce... ------------------------------ From: Arnaldo Echevarria Date: Fri, 6 Sep 1996 20:53:54 -0400 Subject: Re: Ancient History >>> So, how does one take a 400+ CID engine and get that kind of mileage >>> unless he's running a 1.7:1 rear end (i.e. L-O-W r's) -- even if he had >>> 100% VE ? 3.08:1 gears, actually > >So, you're telling me these mpg figures don't bother you? > >Tom Do these numbers really bother anyone? 12mpg highway for a 455? I mean, I've read about 46-48mpg from a turbo v-6; 28-30mpg from 5.7L z/28's, and 31mpg from 5.0L mustangs. While I don't believe any of them; i'd say 12mpg from a 455 is much more believable because I've been driving the car eight months since I built the engine and keep very accurate track of the gas mileage. I calibrate my tach every month - if I spin that engine over 5300rpm it's over - I use a friend's digital speedometer to do so. I know what the correction factor on the speedometer is, It's so precise I can tell tire wear (because the speedometer constant changes just a bit). Just saying so doesn't make it so, I realize that; but believe me, I'm not one of those "oh yeah - 30mpg at least from my v-8". I have driven in far too many 30mpg 5.0L mustangs (only to get 18-20) and 27mpg 5.7L '95 Z/28s (only to get 22.5) Maybe those cars get that kind of mileage at 60mph going down a hill with a tailwind, a real skinny driver and at a high altitude (higher altitudes get better gas mileage, especially with efi). When I say highway, I mean just that: jump on the freeway and drive. That also means slowing down a little, speeding up, passing the old people, showing a Porshe a thing or two :), and finding a place on I75 or I95 to get gas (you know how you get off a freeway only to find out the gas station you're stopping for is out of business and then you realize why the billboard had such a cheap price) AND NOW, A QUESTION, a question: how much better is using some sort of mechanical injection that creates an excellent a/f mixture (dilutes it greatly) over using a conventinal efi injector on the manifold pointing at a valve? Is it really that important that the fuel is injected as close to the valve as possible? At high RPMs it doesn't matter anyway 'cause the fuel will just sit on the valve anyway. What I'm getting at is which plays a greater role at low RPMs: a/f mixture, temp of mixture, or timing of injection? What I'm trying to decide whether I should conceive some sort of mechanical fuel injection system (timed or untimed) or should I just drill 8 injector holes in my intake manifold, buy 8 injectors (not cheap), and go from there? Arnaldo Echevarria aec@xxx.net ------------------------------ From: MaxBoost@xxx.com Date: Sat, 7 Sep 1996 01:14:37 -0400 Subject: Re: Fuel on the intake valves >They mentioned that the injectors have been repositioned and the intake has >a small section cutout along the top of the port allowing the fuel to squirt >more directly on or towards the intake valve. >I thought this was interesting, especially considering we were just talking >about the Hilburn systems. Coincidence???? >-Tom FWIW, Nissan has been doing it since 1984 on their V6 engines. I'm not sure about some of the other makers though. Actually, most of the fuel atomization takes place through evaporation of the fuel on the hot intake valve (at lower engine speeds). Various people have tried open valve injection timing in the past without major success. I have heard it described as "Making Oil" due to the large amounts of un evaporated fuel that gets washed down the bore at lower rpms. Supposedly the only way to make it work is to aim the injector to hit the really hot exhaust valve. Obviously this requires a specific head and manifold setup to accomplish. There was a thread about injection timing and batch vs sequential a while ago on this list that may be archived somewhere. The jist of it was that at WOT and high rpm, injector timing had little effect, due to the limited time available to inject fuel and the ability of the injector to flow fuel. At low engine speed and during transients, injector timing has a BIG effect on response and torque. On another note, I read somewhere that BMW's F1 engine had 4 injectors per cylinder and timed the injection to wait until the exhaust valve closed to start injecting fuel. This was in the fuel economy runs in '85-'86 to save blowing fuel through on overlap. Max. ------------------------------ From: GEGnTx@xxx.com Date: Sat, 7 Sep 1996 01:24:31 -0400 Subject: New follower... Hello, I am building a rather unusual street rod. The parts are coming together nicely so far and it looks like EFI is in my future !! I have looked for the information needed to do the EFI conversion on a 1968 Ford 460 CID and through this newsgroup I will be closer to getting off the information highway and onto I-35 in my dream machine. (I'm really excited about this, so please pardon the background babbling...) The car is a 1979 Mazda RX-7 with a full 2x3 rectangular tube chassis, it has a Mustang II front suspension with 15" Granada rotors GM Calipers and the ECI adapters that make this mix work. The rear end is a narrowed (28" flange to flange) Ford 9" rear with 4-link, coil-overs and 2.75 posi gears to bring in streetable RPM from the C-6 Ford tranny. I picked up a neat program (striptune) from surfing the alt.autos.rod-n-custom newsgroup that helped me justify these choices. (It should run in the low 9's 1/4 mi) The ultimate goal is to have a 1-off streetable big block / small car combo that I can build myself right here at home. I want EFI and turbos also to make my hobby car technically balanced and to put some distance between my car and anything that is considered a "performance" automobile. With this out of the way, I am looking for tips on the EEC-IV Ford computer or anything better suited for large displacement and adaptable for turbo use later. I am starting from the ground up, and right now only have engine hardware (early 460 motor and 1988 EFI manifold/injectors). I have some experience in "C" coding and a good understanding of digital electronics and am ready to learn the controllers, drivers, maps and the rest from you guys... Gary Graham Round Rock, Tx. ------------------------------ From: Jim Steck <72614.557@xxx.COM> Date: 07 Sep 96 01:57:33 EDT Subject: water injection >O.K., My daily driver (w/ 160k miles) is starting to knock unless I use >premium. I think I'll put in a water injection system, but have a few >questions. Can you dump in too much water? I plan on a winshield washer >pump, and to have it vaccum operated. I will monitor the map signal and >start pumping water when the engine gets below a certian vaccum. What >I could do with another op-amp and a 555 is have the water pump come in >at 50% duty cycle at one vaccum, and full on when it drops below another >vaccum. I don't think I'll get carried away with using a pic chip, >because I really don't know the relationship between engine load and >knock. A good treatise on water injection can be found in Sir Henry Ricardo's fourth edition of "The High Speed Internal Combustion Engine" pages 165-171. His experiments were aimed primarily at increasing horsepower in supercharged aircraft engines by way of controlling detonation (with water) so that higher boost pressures could be used. At high boost, normal fuel mixtures were used, and an additional amount of water was added . . . up to 60% of the mass of the fuel. You shouldn't need nearly that much. He also suggested that mixing up to 50% methanol with the water helped improved its volatility. Jim Steck ------------------------------ End of DIY_EFI Digest V1 #264 ***************************** To subscribe to DIY_EFI-Digest, send the command: subscribe diy_efi-digest in the body of a message to "Majordomo@xxx. A non-digest (direct mail) version of this list is also available; to subscribe to that instead, replace "diy_efi-digest" in the command above with "diy_efi".