DIY_EFI Digest Thursday, 14 December 1995 Volume 00 : Number 003 In this issue: re: Reading the crank and OBDII (Camaro) ECM modifications RE: re: Reading the crank and OBDII (Camaro) re: Reading the crank and OBDII (Camaro) re: RE: re: Reading the crank and OBDII (Camaro) Re: EST Systems See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- From: Markus Strobl Date: Wed, 13 Dec 1995 09:59:16 -0600 Subject: re: Reading the crank and OBDII (Camaro) > >By the way this is the way that the Yamaha FZR 600 reads the crank, 3 short > >pulses and 1 long. And this is a very dynamic engine, so dont flame on only > >having 4 triggers per rev please. > > > Wow. The system I'm working on has 144 teeth. Guess I'll be *REALLY* > accurate. :-) I was reading the service manual for a '95 Camaro the other day, and saw something that looked weird. For the LT1 engine (5.7 liter V8), it seems they use TWO crank triggers. One low resolution, and one high resolution. If I recall correctly, the low resolution was 4 pulses per crank revolution, and the high one was 180 pulses per revolution. Does anyone know the reason for this? Is it some sort of failsafe, ie if one sensor failes, the engine runs in 'limp home mode'? I was impressed by some features of the engine management. One that I particulary liked was that the LT1 is a MAF type engine, but if the MAF sensor failes, the ECM will switch to speed density. Neat. Second subject: I own a '96 Camaro with the LT1. The service manual I read was for a friends '95. GM did alot of changes for '96 to comply with OBDII. My owners manual says that the ECM now detects misfires, and will flash the service engine light if it detects a misfire. The '96 also has 4 (!) O2 sensors (dual cat), to detect catcon degradation. Does anyone have any info on OBDII? Ie how much can the engine be modified before the ECM tilts? Can the ECM be modified, or can it be fooled be changing the sensor readings? Any info appreciated. BTW, I won't buy the service manual for the '96 yet, because it still has 'Preliminary' written on it with big red letters. I want to wait until the final version is out. Markus Strobl 96 Z28 6M. !CAGS, 1LE driveshaft, PEG2, QLC, T-tops, leather. Black. Dallas, Texas 14.09 @xxx. ------------------------------ From: jsturs@xxx.nl (Jim Sturcbecher) Date: Wed, 13 Dec 1995 20:11:03 -0100 Subject: ECM modifications On Weds 13 Dec, Markus wrote: >Second subject: I own a '96 Camaro with the LT1. The service manual I >read was for a friends '95. GM did alot of changes for '96 to >comply with OBDII. My owners manual says that the ECM now detects >misfires, and will flash the service engine light if it detects a >misfire. The '96 also has 4 (!) O2 sensors (dual cat), to detect >catcon degradation. > >Does anyone have any info on OBDII? Ie how much can the engine be >modified before the ECM tilts? Can the ECM be modified, or can ----------------------- >it be fooled be changing the sensor readings? Any info appreciated. > Markus, suggest you cure your static shock problems before playing with the ECM ;-) ;-) Fellow f-body lister? PS. remember what the smilies mean... Jim Sturcbecher jsturs@xxx.nl ------------------------------ From: m_mcdonald@xxx.com Date: Wed, 13 Dec 95 14:15:08 EST Subject: RE: re: Reading the crank and OBDII (Camaro) Markus Strobl has written: > Second subject: I own a '96 Camaro with the LT1. The service manual I > read was for a friends '95. GM did alot of changes for '96 to > comply with OBDII. My owners manual says that the ECM now detects > misfires, and will flash the service engine light if it detects a > misfire. The '96 also has 4 (!) O2 sensors (dual cat), to detect > catcon degradation. > Does anyone have any info on OBDII? Ie how much can the engine be > modified before the ECM tilts? Can the ECM be modified, or can > it be fooled be changing the sensor readings? Any info appreciated. An excellent source of information about OBD-II (On-Board Diagnostics, Level II) is the rule issued by the Environmental Protection Agency (EPA) on August 9, 1995. This rule has background information about the vehicle emission reduction requirements that led to OBD-II hardware and software. It also has pointers to additional information such as emissions-related data that all auto manufacturers must make freely available to the public. Fortunately, this emissions-related data contains much engine-performance-related data. The EPA rule has the formal title 40 CFR (Code of Federal Regulations) Parts 9 and 86 that appear on pages 40474 through 40498 of the Federal Register (Volume 60, Number 153). Any local EPA office should have the rule available for reading and photocopying. It's supposed to be available on the Internet by pointing your favorite browser to http://wais.access.gpo.gov or by telnetting to fedworld.gov and giving the command "/go epa" once you've registered and are at any menu. After issuing this command you should be able to find both the EPA rule and manufacturer-provided indexes to their cars' emissions- related data. As a last resort, send me an e-mail request and I'll reply with the EPA rule as a long=180,000 byte file. Another source of information is the OBD-II specifications for hardware and data stream messages. The Society of Automotive Engineers (SAE) in Warrendale, Pennsylvania has a 1995 manual about this. Its number is either HS-3500 or HS-3000. The cost is about $65.00 (ouch!), but the contents are invaluable for someone who wants to interface his own IBM-compatible PC to his car's data stream. Warrendale, PA has a 412 area code and the SAE accepts plastic. Yes, the ECM can be temporarily overriden by electronic tools connected to a vehicle's OBD-II connector. This allows technicians to perform various diagnostic tests. Marll McDonald KB1AGM m_mcdonald@xxx.com ------------------------------ From: pjwales@xxx.net (Peter Wales) Date: Wed, 13 Dec 1995 15:41:20 -0500 Subject: re: Reading the crank and OBDII (Camaro) >I was reading the service manual for a '95 Camaro the other day, and saw >something that looked weird. For the LT1 engine (5.7 liter V8), it seems >they use TWO crank triggers. One low resolution, and one high resolution. >If I recall correctly, the low resolution was 4 pulses per crank revolution, >and the high one was 180 pulses per revolution. > >Does anyone know the reason for this? Is it some sort of failsafe, ie >if one sensor failes, the engine runs in 'limp home mode'? My guess is that they wait for the 4 tooth one to pass to identify 90 deg BTDC and the count the 180 one to get within 2 degrees of the correct timing then set the counter off to delay until the timing comes correct. Also, I would start charging the coil up at 90 deg BTDC and use a variable dwell angle Peter Wales President Superchips Inc Chairman Superchips Ltd "Timing is everything" ------------------------------ From: SRavet@xxx.com Date: Wed, 13 Dec 95 18:42:28 CST Subject: re: RE: re: Reading the crank and OBDII (Camaro) m_mcdonald@xxx.com Wrote: | | | Markus Strobl has written: | | | | > Second subject: I own a '96 Camaro with the LT1. The service manual I | > read was for a friends '95. GM did alot of changes for '96 to | > comply with OBDII. My owners manual says that the ECM now detects | > misfires, and will flash the service engine light if it detects a | > misfire. The '96 also has 4 (!) O2 sensors (dual cat), to detect | > catcon degradation. | | > Does anyone have any info on OBDII? Ie how much can the engine be | > modified before the ECM tilts? Can the ECM be modified, or can | > it be fooled be changing the sensor readings? Any info appreciated. | | | | An excellent source of information about OBD-II (On-Board Diagnostics, | Level II) is the rule issued by the Environmental Protection Agency | (EPA) on August 9, 1995. This rule has background information about | the vehicle emission reduction requirements that led to OBD-II hardware | and software. It also has pointers to additional information such as | emissions-related data that all auto manufacturers must make freely | available to the public. Fortunately, this emissions-related data | contains much engine-performance-related data. I skimmed this document, all I really got out of it was that the EPA is requiring manufacturers to make available to the general public all emmissions related repair information that they make available to their dealers. (available not implying free). It also seems to require that reprogramming of the ECM be allowed, and the information to accomplish that must be made available. But the information can be made available indirectly, in the form of a device that can reprogram the ECM, without actually revealing how to reprogram it. Did I miss anything? | | The EPA rule has the formal title 40 CFR (Code of Federal Regulations) | Parts 9 and 86 that appear on pages 40474 through 40498 of the Federal | Register (Volume 60, Number 153). Any local EPA office should have | the rule available for reading and photocopying. It's supposed to | be available on the Internet by pointing your favorite browser to | http://wais.access.gpo.gov or by telnetting to fedworld.gov and giving | the command "/go epa" once you've registered and are at any menu. | After issuing this command you should be able to find both the EPA | rule and manufacturer-provided indexes to their cars' emissions- | related data. As a last resort, send me an e-mail request and I'll | reply with the EPA rule as a long=180,000 byte file. These indices are basically a list of the available service manuals, TSB, training kits, etc. Each has a note attached saying to contact *whoever* to purchase the information. It's presented as a list of files like this: gmc0001.txt gmc0002.txt .. doing a search for "corvette" and "bulletin" results in a list of TSBs related to corvettes. The training kits looked interesting, they included: Description: Corvette CCM *3 * Description Information 1 = Manual 2 = Student Workbook 3 = Instructor's Guide 4 = Overhead Slide Set 5 = Binder 6 = Student Package 7 = Systematic Troubleshooting Poster 8 = Complaint Description Form 9 = ECM Inputs Exercise 10 = ECM Outputs Exercise Prices ranged from $10 to $25 or so. I wonder if anyone knows what is really in these kits? | | Another source of information is the OBD-II specifications for | hardware and data stream messages. The Society of Automotive Engineers | (SAE) in Warrendale, Pennsylvania has a 1995 manual about this. Its | number is either HS-3500 or HS-3000. The cost is about $65.00 (ouch!), | but the contents are invaluable for someone who wants to interface | his own IBM-compatible PC to his car's data stream. Warrendale, PA | has a 412 area code and the SAE accepts plastic. | | Yes, the ECM can be temporarily overriden by electronic tools connected | to a vehicle's OBD-II connector. This allows technicians to perform | various diagnostic tests. | | Marll McDonald KB1AGM | m_mcdonald@xxx.com | | Steve Ravet sravet@xxx.com Baby you're a genius when it comes to cooking up some chili sauce... ------------------------------ From: dn Date: Wed, 13 Dec 95 22:17:18 MDT Subject: Re: EST Systems To revive an old thread, I think I may have stumbled onto the key to the GM 7 pin ignition module. After seeing on some thread a reference to the Motorola MC3333 ignition control chip, I started browsing some of my data books for ignition controllers and remembered that Allegro Microsystems makes a lot of specialty automotive chips. I looked in their automotives section, and sure enough, they make a chip called, appropriately enough, an Electronic Spark Timing Controller, their part number ULQ2460A. After reading through the data sheet, it struck me that the device they were describing matches the info that I have on the GM 7 pin module EXACTLY! The chip is "intended to interface between conventional electromagnetic pickups, a computer controlled electronic spark timing (EST) computer, and a high efficiency ignition coil" (quoted from the databook). They even call it an EST! After looking more closely at the data sheet, they describe an application schematic where there are 3 connection points to the computer: 1. Reference - signal conditioned output from the pickup 2. EST (Electronic Spark Timing) - control input from the EST computer, allows the CPU complete control over ignition functions 3. Bypass - causes the device to internally process the Reference signal to control dwell, spark timing, and spark advance without the aid of the computer Coincidence? I think not! Of course, the applications schematic shows a few external components, including some RC time constants, a PNP darlington coil driver, etc., but the description is almost word for word the same as GM's own description of the module. The good part of all this is that the data sheet lists all the thresholds for the inputs and outputs, and gives an internal schematic of the chip which shows the innermost secrets of the device. For anyone who is interested, the address for these guys is: Allegro Microsystems Inc. 115 Northeast Cutoff Box 15036 Worcester MA 01615 Voice (508) 853-5000 Fax (508) 853-5049 You should be able to call their Customer Service department and request a free copy of the databook. Also, if you lie through your teeth and tell them that you're going to buy 10,000 or so units, they can probably be convinced to send you some free engineering samples. | Specific to jwharris: | I recall in an earlier message in this thread you said that you had | access to schematics of the modules, I wonder if it would be a | breach of confidentiality to confirm whether or not this is the main | component of the Delco module? If not, it will save me and probably | others a lot of time dinking around with a scope under the hood of | the ol' Chebby. If so, I think that I have sufficiently convinced | myself that this is, indeed the heart of the EST "7 pin" module and | I will proceed merrily on from here. regards dn - -- \/<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>/\ ------------------------------ End of DIY_EFI Digest V0 #3 *************************** 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".