From: James D. Viglietta [nebraska@pacifier.com] Sent: Monday, February 14, 2000 8:51 AM To: 928 Subject: [928] Re: F.I. brains rebuilt I dropped these folks an e-mail on the spare ECU for my car,this is the reply I got: <> Replying to my own post for the general interest of the group,this does not sound unreasonable to me. That price was for a MY '80 US L-jet/lambda Jim Viglietta '80 petrolblaumetallic From: partwerks9@aol.com Sent: Wednesday, December 06, 2000 4:45 AM To: 928 Subject: [928] 928 S4 Brain Rebuilds Now Available It has has been several years since we have been able to have the 928 S4 brains rebuilt affordably in competition with Porsche. A very specific chip set that goes bad had became unavailable and we were unable to have these brains rebuilt. Right now we were able to obtain a shipment of chips and can again rebuild these units. We are charging $495.00 with a $200.00 core charge and a 12 month warranty. We have already shipped one brain, and have only one other rebuild unit in stock, after that we have no other cores. You can purchase this unit or send your broken unit in for rebuild. Because of the problems we have had in the past with availability of chip sets I recommend that you jump to the head of the line if you are needing a brain or just want to stock an extra one. Jay Part Werks of Chicago 815-462-3000 800-366-9147 >I have talked to the guy who runs this business. He seamed like a >reasonable guy. I originally got his name off of a Volvo list. He said he >would rebuild my AMS for $100 with a lifetime guarantee. I was looking into >getting a rebuild but did not get one done yet. I would certainly give him >a shot if I needed to. >I spoke with Kevin at; >INJECTION LABS >1436 Industrial Way >Gardnerville, NV 89410-0572 >775 782 8544 >Ken Postma '86 928S -----Original Message----- From: Ken Steinberg [mailto:kens@fullmoonmotivation.com] Sent: Tuesday, March 05, 2002 3:48 PM To: 928 Subject: [928] Success: Bosch 928 LH injector rebuilt! I want to let everyone know, I sent my Bosch LH injector brain to PartWerks in Chicago, got it back and it works like a charm. Half the cost of a new one and they even repainted the cover. As a matter of fact the base for the PC board looks to be completely remilled also. Very nice job. It took a month to get it done, but for $500 it was worth it. She fired right up. If you have similar problems, I recommend them. Ken 85 928S4, 86.5K miles (starting to look more like a 1998!) From: mirror [mailto:mirror@interfold.com] Sent: Saturday, July 27, 2002 6:34 AM To: john.pirtle@rennlist.com Subject: Injector Brain repairs Hello John, What a nice reference site you have built. I see many, many hours in compiling and catagorizing information on the 928 S4. I've decided to buy one soon, and have a bit of information on the brain of the Bosch unit. It's not good news I'm afraid. The reading I've done, and a bit of research with people I work with, lead me to provide the following insight. The "brain" of the LH unit is a closed loop servo monitoring system, with digital management. There is at least one A/D (analog to digital) converter to accept input from the various sensors in the fuel management loop such as the MAF, O2, MAP, fuel pressure, temperature, etc. These inputs are 'massaged' by the computer and matched to a set of output scripts that are then sent to a D/A (digital to analog) circuit providing injector pulse start timing, pulse width, Throttle Position openning, and ignition advance or retard as required to perform a complete burn of the incoming air supply. A stoiciometric ratio of about 15:1 air to fuel is optimal for internal combustion gas engines. Perhaps you are aware of all this already and I'm just recapping and wasting time, but the overview is important to know what goes wrong. Now, much of the brain digital circuitry is quite stock in terms of function and availability. I read a post where one enterpising owner fixed his car with a simple dual digital NOR gate model 7402. Another had all the stock TTL components replaced and things went swimmingly. These repairs are quite ordinary for a digital circuit technician, and if that fixes the problem, great! But...what if it doesn't? The special circuits on these units are: CPU; ROM; and ASIC. Most of us would know that the CPU is the Central Processing Unit, and that the ROM is the Read Only Memory, but what is an ASIC? This is the Application Specific Integrated Circuit. Lets take things one at a time. The CPU performs comparison calculations by reading the digitized values found on the inputs, and comparing those values to pre-defined values populated in the ROM (factory settings, or curves). Those comparisons then provide a set of outputs to the aforementioned D/A converter, and the injectors, ignition module and Throttle Position are moved accordingly. The CPU performs probably 4 bits at a time (bus width) and operates at a blazing 500-900Khz (that's Kilohertz) speed. Strangely enough, this is plenty of process power to get the job done as we aren't doing intensive things like rendering 3D graphics, or multithread database updates. Just simple old move, add, compare, resultant. For the mid-70s this was state of the art in automotive hi-tech. Now the ROM. This may, or may not be an off the shelf type component. There are certainly plenty of ROM chips available that would do the job, and can be had for very low cost. However, the application (auto) would indicate that a special ROM was developed to handle the stresses and environment typical of it's intended use. The ROM is used to store the values for injector timing, pulse width, ingnition timing, and TB openning for all conditions that the car may encounter. There is much speculation about wheather all, or some of the units are adaptive. Meaning that the system will become 'characterized' based on previous operating parameters. I do not have any information on this aspect, but I would venture to say that a heuristic (learning) system was developed for the US cars simply due to the strict emission requirements in some states (Ca). Also, as the technology improved between 1985 and 1989, it would make sense that the ROMs storage capacity would be increased to handle more than one 'profile', leading to the adaptive method for engine control. The ROM is burned in that the values for the sensors and servos are permanently set into the circuitry of the chip. When we talk about "chipping" a car, this is the part that is exchanged with custom values. Current technology allows many vendors (Compmotive, et. al.) to connect a laptop computer to a brain and modify curves on the fly, while the car is in operation. These systems are both adaptive, and dynamically alterable by the engineer during the test run. The previous two components may, or may not be commercially available depending on what Bosch decided regarding the application. My guess is that they were custom made units in conjuction with a major IC design group, specifically for Bosch, who in turn used the components for many cars, not just the 928. This leads us to the real culprit of the brain. The ASIC. As it's name implies, it is Application Specific. For example, if we ask "how does the CPU know which registers (input lines) to read at which time"? Or, "when I compare the MAP from the car, to the MAP in the ROM table, should I increase or decrease the injector pulse width"? These are just two of the thousands of situations that the CPU may encounter. There must be a valid and unique answer to each of these many-fold situations, or the CPU will hang, and the car will not run. All this digital code is called the "instruction set" and it is logically coded into the ASIC. Each ASIC for a given model (microwave oven, F.I., VCR) is specific. And the instruction coding is a closely guarded secret. It requires hundreds of hours to develop and test this code, and is very, very expensive. This is why Bosch is unresponsive to requests for brain information, and rebuild parameters. Sometimes the CPU and ASIC are combined into one package, which may be called a LSI (Large Scale Integration) module. Later products put the CPU, ROM, and ASIC all together and called it a VLSI (Very...) circuit. When things go bad. It worries me that an owner found a simple 7402 chip in his 928 brain. If we know the entire part number we could determine if Bosch used hardened packaging for their chips, or just off the shelf components designed for the likes of home computers, and microwave oven controls. When an ASIC is designed, the packaging is as specific as the logical coding that goes into it. There is packaging for: Military spec, Automotive spec, Nuclear reg spec, etc. Since the failure mode isn't clearly well known, we can't pin down what exactly is the causative factor in the failures of the brain. Some things we do know in general: Electronic components HATE heat. The kind found under a car hood is a good example. Heat means resistance, resistance, means more heat. See a trend here? They also HATE voltage fluctuations. I.E. the type found in a system where we rely exclusively on chemical batteries, and there is constant mega-current (starting) drain and then quickly followed by jolts from an unbuffered alternator winding. Gee, what a poor environment to operate sensitive electronics in. It's a wonder any of it lasts for 10+ years. There is some logic in the exemplary maintenance of the electrical system on these cars. Keep a good battery; don't leave the car out in very cold climates; never jump start another car or get a jump from someone; after starting, let the engine sit at idle for 30 seconds or so to give the alternator time to refresh the charging circuit. This will have a beneficial affect on all the circuits in these cars and that's saying a lot. As for "rebuilding" a brain. If we could get Bosch to open up and provide ASICs, ROMs, and CPUs, the job isn't difficult for anyone with a steady hand, a solder/desolder station, and a set of good eyeglasses. The cost of the parts should be well amortized by now, and I would think that Bosch might like to make some money on the part sale, especially since they created the hydra monster in the first place by not spec-ing the original parts correctly for the environment. If you have a 928 brain apart on the bench sometime, expose the circuit card, look for large square, or large rectangle components with more than 14 "pins" probably near the center of the board. Then with a good light and a magnifying glass write down EVERYTHING on the parts mentioned and email it to me. I'll try to contact the manufacturer and buy the license to build some, or have Bosch license me to OEM these chips to the 928 community. feel free to edit, or amend as you see fit. You may distribute this opus freely, but I would appreciate an honorable mention. If you have specific questions regarding IC design and building I will try to answer them without becomming overly scientific. Happy motoring, Doc 37 Cord Beverly 70 Lamborghini Espada 75 Matra Bagheera 63 Studebaker Avanti R2 62 VW 21 window bus -----Original Message----- From: Rich [mailto:rich9928@earthlink.net] Sent: Thursday, May 08, 2003 12:55 AM To: 928 Subject: [928] Re: LH Injection Controller Repair For customers from USA, Canada, Australia... the repair price is 350 US$ without taxes plus shipping. For details contact Mr. Mueller directly. He speaks English. --------- > I'm passing on a message from a German 928 owner .... > Rich > --------------- > I think this message could be important for any S4, GT, GTS driver. These > cars use the Bosch LH-Jetronic fuel injection controller. > > The price for checking a controller is 50€ plus shipping. > -------------------------------- > Firma ACM > Herr Müller > + 49 69297 929462 > email mueller.acm@t-online.de > --------------------------------