DIY_EFI Digest Thursday, 1 February 1996 Volume 01 : Number 028 In this issue: Re: SBC TPI manifold questions Re: What processor does GM use Re: efi555 Re: Sensor Questions? Re: SBC TPI manifold questions Bosch Mono-Jetronic Re: Bosch Mono-Jetronic Re: Bosch Mono-Jetronic re: Re: Sensor Questions? re: Re: Sensor Questions? Re: Re: Sensor Questions?r Learning mode (was Re:Sensor Questions?) re: Re: Sensor Questions? Re: SBC TPI manifold questions Re: Bosch Mono-Jetronic Re: Engine codes Re: Re: Sensor Questions? See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- From: FIScot@xxx.com Date: Wed, 31 Jan 1996 08:11:44 -0500 Subject: Re: SBC TPI manifold questions Subj: SBC TPI manifold questions Date: 96-01-30 22:30:57 EST From: jsg@xxx.edu (John S Gwynne) > Just a couple of quick question... I don't really want to buy a > service manual for this car since I only have its manifold. > Manifold: 89 Camaro TPI 305 w/ cold start injector Check the year, 89 Camaro's did not use the cold start injector. > Q) The EGR valve has what looks like a temperature sensor built into > its base. How is that used? It is used in EGR testing. It is mounted on the output side of the EGR valve. If the EGR is on, it gets hot, and activates the switch, if the EGR gets turned off, it cools, and deactivates. The EGR test checks this for proper operation. > Q) I've traced the idle air passages down through the base plate. Near > the cold start injector there is a hose nipple. What attaches here? > Does this tee-off to the MAP sensor which I assume is attached to > the rear left nipple on the plenum? The first mentioned nipple is for the PCV valve. Nothing else is hooked to it. The MAP is connected to a nipple in the plenum. The 85-89 TPIs used a MAF sensor, so had no MAP provisions. The 90-92 used MAP, and had a plenum that had a MAP sensor mount and nipple. Just use a plenum nipple. (Personal opinion: MAF's are ugly.) Are you going to use a MAP sensor? Do you have your VE table yet? > Q) How did GM originally route the radiator bypass hoses? One through > the throttle body then back to the block and a second to the heater? The large nipple on the front of the throttle body is for the incoming hot water out of the manifold. The throttle body exit did go to a switch that was controlled by the HVAC system. Normally this would go to the heater core, but the heater core is shut off during max A/C, and the the switch keeps the throttle body warm at all times. Scot Sealander FIScot@xxx.com HVAC - Heating, Ventilating, and Air conditioning MAF - Mass AirFlow sensor MAP - Manifold Absolute Pressure sensor TPI - Tuned Port Injection VE - Volumetric efficiency ------------------------------ From: Matt Sale Date: Wed, 31 Jan 1996 08:47:38 -0500 (EST) Subject: Re: What processor does GM use > > Could anyone tell me what micro processors GM uses for it's ECM boxes > > Thank You > frank.micciola@xxx.com > Most GM ECM's are supplied by Delco Electronics and use derivatives of the 68HC11 or more recently, the MC68332. Early systems used derivatives of the NMOS MC6800 family. - -- Matt E-mail: mds@xxx.com #include ------------------------------ From: ducharme@xxx.com (CF Ducharme) Date: Wed, 31 Jan 96 09:16:48 EST Subject: Re: efi555 ------------------------------ From: Wayne Braun Date: Wed, 31 Jan 1996 08:49:00 -0600 Subject: Re: Sensor Questions? Text Deleted. > > Guilty as charged. BLM is usually a 4x4 matrix that has on one axis > an RPM component and on the other, a load component. This matrix is > updated when the ECM is in closed loop and BLM learn conditions are > met. The particular BLM that is used is defined by the particular > combination of RPM and load. If the ECM is operating in open loop, the > ECM can still operate close to the ideal AFR (air/fuel ratio) by using > the 'learned' value of BLM. > > Seeing as GM does not necessarily use hard and fast rules, the number > of BLM locations can be as few as 2, to as many as 16 BLM locs. > (Personal experience cited.) > > > Unfortunately, this points directly at Mr. Sealander and I do not mean > > to single him out as the only person that does this. After all, he is > > NOT the only person that does this. I ended up re-reading one > > paragraph several times ( in someone elses posting ) before the term > > "catcon" fell into place as meaning catalytic converter. > > I guess we all sometimes assume a basic level of understanding that is > uniform all around. > Text deleted > > Mr. Sealander, I do enjoy reading the information that you have > > provided even if I sometimes have to work to understand them ( that may > > not be a bad thing either 8^)). > > Hey, that's good for you! There is really is no substitute for > personal effort! > > Scot Sealander FIScot@xxx.) > Thanks, it makes a lot more sense now. I guess maybe its time to put some of this information into a FAQ Wayne. Wayne Braun Product Support Develcon Electronics Email: Wayne.Braun@xxx.com Phone: (306) 933-3300 or 1-800-667-9333 FAX: (306)978-8860 ------------------------------ From: John S Gwynne Date: Wed, 31 Jan 96 10:21:58 -0500 Subject: Re: SBC TPI manifold questions In message <960131081142_210770196@xxx.com> , you write: | > Manifold: 89 Camaro TPI 305 w/ cold start injector | | Check the year, 89 Camaro's did not use the cold start injector. ok... underside of plenum shows a casting date of Sept 87. Maybe it's an 88? | Are you going to use a MAP sensor? Do you have your VE table yet? Yes, MAP. Any VE date would be helpful if that's an offer :). | > Q) How did GM originally route the radiator bypass hoses? One through | > the throttle body then back to the block and a second to the heater? | | The large nipple on the front of the throttle body is for the incoming | hot water out of the manifold. The throttle body exit did go to a | switch that was controlled by the HVAC system. Normally this would go | to the heater core, but the heater core is shut off during max A/C, and | the the switch keeps the throttle body warm at all times. On the base plate there are three holes into the coolant passage. One still has a coolant temperature sensor (CTS), another a bypass hose to the throttle body, and the third is empty. What originally attached to this last location? Throttle body questions: Q) I would guess the top hose connection on the right side is a for the charcoal canister (just filtered fresh air). Correct? Q) The second one down on the right looks like a "typical" vacuum port. Sound about right? Q) Now the tough one... there is a port vacuum signal near the left throttle plate that works its way down to the bottom left of the throttle body just behind the coolant passage. I have a hole here with no hose barb or anything. I assume something use to attach here; what? Thanks for the help. John S Gwynne Gwynne.1@xxx.edu _______________________________________________________________________________ T h e O h i o - S t a t e U n i v e r s i t y ElectroScience Laboratory, 1320 Kinnear Road, Columbus, Ohio 43212, USA Telephone: (614) 292-7981 * Fax: (614) 292-7297 - ------------------------------------------------------------------------------- ------------------------------ From: wrm@xxx.za (Wouter de Waal) Date: Wed, 31 Jan 96 17:09 GMT+0200 Subject: Bosch Mono-Jetronic Hi all I recently started looking at the FI system in my wife's Fiat Uno again, after it developed a flat spot on accellerating. The system consists of a single injector in the throttle body, an inlet air temp sensor, a throttle position sensor, a servo to control the throttle at idle (idle speed), a water temp sensor and a lambda sensor. And engine rpm info is sent to the system from the ignition computer. Question 1: How? As I understand things, you need to know the load on the engine. How does this system find the load? Perplexing. The only thing I can think of is that the mixture is controlled by the closed loop system, even under acceleration etc. But would the lambda sensor be fast enough? Would a slow lambda sensor then cause a flat spot? Ooooh, my head hurts :-) Question 2: This thing has a diagnostic port, to be read by a "Fiat something-or-other tester" which I obviously don't have. Seems to be three-wire. Anybody know what the protocol is likely to be? Peter? Should I put a scope on it and see what comes out? Should the ignition be on, or the engine running, when I do this? Thanks! Wouter - -- Wouter de Waal ZS1KE GE>AT d-(pu) s+:-- a- C++$ UL+ U*+$ P>++ L++ E- W N+++>++ Argo 505 / FT200 !o K w(--) !O !M V(--) PS+ PE++ Y+ PGP>++ t 5? X? R? tv>--- b+++ DI+ D+ G e+++(*) h--- r+++ y+++(*) '72 Puma - 1700 FI Type IV engine Perseverance my son, '6? Series IIA SW - factory fitted Lucas immobiliser it's a Land/ /Rover "All journeys end when we reach our destination but the journeying remains a thing apart, unique unto itself. Most of us make life's journeys without understanding that the journeying is a separate thing." -- Bob Hoover ------------------------------ From: atsakiri@xxx.com Date: Wed, 31 Jan 96 12:08:15 -0500 Subject: Re: Bosch Mono-Jetronic > The system consists of a single injector in the throttle body, an inlet air > temp sensor, a throttle position sensor, a servo to control the throttle at > idle (idle speed), a water temp sensor and a lambda sensor. And engine rpm > info is sent to the system from the ignition computer. > > Question 1: How? As I understand things, you need to know the load on the > engine. How does this system find the load? Perplexing. The only thing I can > think of is that the mixture is controlled by the closed loop system, even > under acceleration etc. But would the lambda sensor be fast enough? Would a > slow lambda sensor then cause a flat spot? Ooooh, my head hurts :-) Perhaps load is determined from engine speed, throttle position, and barometric pressure (though there's no mention of a barometric pressure sensor above). The breathing characteristics of the engine could be mapped quite well as a function of these parameters. Anthony Tsakiris - --------------------------------------------------------------------------- The opinions expressed are my own and not necessarily those of my employer. ------------------------------ From: Land Shark Date: Wed, 31 Jan 1996 11:31:06 -0700 (MST) Subject: Re: Bosch Mono-Jetronic At 05:09 PM 1/31/96 GMT+0200, you wrote: >I recently started looking at the FI system in my wife's Fiat Uno again, >after it developed a flat spot on accellerating. > >The system consists of a single injector in the throttle body, an inlet air >temp sensor, a throttle position sensor, a servo to control the throttle at >idle (idle speed), a water temp sensor and a lambda sensor. And engine rpm >info is sent to the system from the ignition computer. What .. NO MAP sensor .. and no AIR FLOW or AIRMASS sensor??? are you SURE??? >Question 1: How? As I understand things, you need to know the load on the >engine. How does this system find the load? Perplexing. The only thing I can >think of is that the mixture is controlled by the closed loop system, even >under acceleration etc. But would the lambda sensor be fast enough? Would a >slow lambda sensor then cause a flat spot? Ooooh, my head hurts :-) Well, in most BOSCH systems .. load .. called Tl is measured like this .. Q(kg/hr)=f(Up/Uv) Tl=Q/(N*Ki) Ti=(Tl*[c1,c2,c3])+Cvolt Where Q is the airmass as a function of the incoming air sensor voltage on the air FLOW sensors it is an exp function .. on the AIRMASS Hot films, a bit more complicated ... Tl (load) is made from Q, n (rpm), and Ki, the injector flow constant From there .. Ti is formed by applying multiplicative lambda corrections to Tl and then adding the correction for battery voltage .. Ti, time for injection, is applied directly to the injector ... >Question 2: This thing has a diagnostic port, to be read by a "Fiat >something-or-other tester" which I obviously don't have. Seems to be >three-wire. Anybody know what the protocol is likely to be? Peter? Should I >put a scope on it and see what comes out? Should the ignition be on, or the >engine running, when I do this? Check out ISO-9141 ... If you can get a jump of the internal EPROM, maybe we can figure it out ... Jim ------------------------------ From: SRavet@xxx.com Date: Wed, 31 Jan 96 17:39:34 CST Subject: re: Re: Sensor Questions? Markus Strobl Wrote: | | The Q of MAF vs speed density has come up in 2 mailing lists at once, | so this goes out to both lists... | | | > Interesting, Scot. It doesn't seem that there is really a need for a MAF, | > then. Is MAF just an aid to enable the CPU to learn better? Or is there a | > MAF term in the fuel equation? | > | > --steve | | I like to think about it this way (it is a bit simplified, but it's | basically true): | | A speed density (SD) system will only know how much air is entering the | engine as a percentage of the maximum flow. For instance, driving at half | throttle at a certain condition may tell the ECM the engine is using 50% | of maximum flow. Dyno test run by the manufacturer indicate that max | flow is 600 cfm (cubic feet per minute) of air. The ECM then knows how | much fuel to inject for 300 cfm of air. | | This sounds like a perfect setup, until you start to think about it. | Production tolerances will affect max flow in an engine (casting flash, | mismatched cylinderheads-to-manifold, etc). Also, max flow will change | as the engine ages. And we haven't even started considering modifications | such as ported heads, hotter cam etc. | | So as soon mods are made to a SD engine, a new chip has to be burnt. But if an O2 sensor is available, the SD tables can be updated as the ECM learns lean or rich conditions. That is the BLM (block learn mode) that Scott Sealander referred to. BLM is basically a percentage that the pulse width is modified by. IF you add headers, BLM increases pulse width across the board, and this is still used even in open loop mode. So an SD system is capable of learning about modifications. Steve Ravet sravet@xxx.com Baby you're a genius when it comes to cooking up some chili sauce... ------------------------------ From: SRavet@xxx.com Date: Wed, 31 Jan 96 17:47:44 CST Subject: re: Re: Sensor Questions? FIScot@xxx.com Wrote: | | Subj: re: Re: Sensor Questions? | Date: 96-01-30 19:26:41 EST | From: SRavet@xxx.com | | | > Interesting, Scot. It doesn't seem that there is really a need for a | > MAF, then. Is MAF just an aid to enable the CPU to learn better? Or | > is there a MAF term in the fuel equation? | | Right, the MAF term was included in the right hand part of the | equation. The MAF is the primary input the cpu considers for injecting | fuel. The BLM is a correction term. (MAF = Mass AirFlow sensor) | | Scot Sealander FIScot@xxx.com | Oh man, now I'm confused. MAF isn't good as the basis for fuel injection alone, since the amount of air past the MAF sensor isn't necessarily the amount of air into the engine. Remember the plenum stores air, so a sudden increase in the amount of required air will draw a vacuum on the plenum before the MAF actually sees the increase in airflow. So I've been told that even MAF based systems use SD for the basic pulse width, and the MAF term is just a learning input. Besides, as Scott explained earlier, SD systems are perfectly capable of learning about engine modifications, so what's the need for MAF? Is this true or not? Steve Ravet sravet@xxx.com Baby you're a genius when it comes to cooking up some chili sauce... ------------------------------ From: lusky@xxx. Lusky) Date: Wed, 31 Jan 1996 19:14:39 +73800 (CST) Subject: Re: Re: Sensor Questions?r SRavet@xxx.com writes: > But if an O2 sensor is available, the SD tables can be updated as the ECM > learns lean or rich conditions. That is the BLM (block learn mode) that minor correction: BLM = Block Learn Multiplier Some other GM ECM terms i see in my old notes... OT = Injector on-time BPC = base pulse constant F/A = fuel-air ratio VE = volumetric efficiency DFCO = Decelration fuel cut-off DE = deceleration enleanment AE = acceleration enrichment PE = power enrichment EST = electronic spart timing IAC = idle air control IACV = idle air control valve ALDL = assembly line diagnostic link TCC = torque converter clutch - -- Jonathan R. Lusky lusky@xxx.edu http://www.hotrod.com (615) 726-8700 - ------------------------------------- ------------------------------ 68 Camaro Convertible - 350 / TH350 \_/ 80 Toyota Celica - 20R / 5spd ------------------------------ From: "Zublin, Bryan (SD-MS)" Date: Wed, 31 Jan 1996 18:07:00 -0800 (PST) Subject: Learning mode (was Re:Sensor Questions?) Steve Ravet wrote: >But if an O2 sensor is available, the SD tables can be updated as the ECM >learns lean or rich conditions. That is the BLM (block learn mode) that >Scott Sealander referred to. BLM is basically a percentage that the pulse >width is modified by. IF you add headers, BLM increases pulse width across >the board, and this is still used even in open loop mode. So an SD system >is capable of learning about modifications. At low flow rates / low load conditions, this makes sense. However, at higher loads and wide open throttle, how is the ECU going to learn that the volumetric efficiency has changed? It would have to lean out the mixture to stochiometric, which is very dangerous under full throttle conditions. The O2 sensor basically reports that the a/f ratio is above or below stochiometric, so to get any useful info (ie. learn), the engine would have to be closed loop. From what I've read in the efi books, the engine *never* runs closed loop when at wide open throttle. Bryan Zublin bzublin@xxx.com ------------------------------ From: Land Shark Date: Wed, 31 Jan 1996 19:41:44 -0700 Subject: re: Re: Sensor Questions? At 17:47 1/31/96 CST, you wrote: >Oh man, now I'm confused. MAF isn't good as the basis for fuel injection >alone, since the amount of air past the MAF sensor isn't necessarily the >amount of air into the engine. Well, that's how BOSCH has done it since umm .. forever .. There are *compensations* to MAF/rpm to make the pulse width up, but the basis for fuel injection time is MAF signal ... Also, things like delta MAF are used to signal acceleration and also throttle position, etc etc etc ... >Besides, as Scott explained earlier, SD >systems are perfectly capable of learning about engine modifications, so >what's the need for MAF? Is this true or not? No, not unless the # of BLM cells (or adaptive locations) is equal to the number of possible fuel map cells under those conditions .. so that EVERY point in the fuel map is compensated .. to it's needed adjustment Jim ------------------------------ From: FIScot@xxx.com Date: Wed, 31 Jan 1996 22:47:42 -0500 Subject: Re: SBC TPI manifold questions Subj: Re: SBC TPI manifold questions Date: 96-01-31 11:11:38 EST From: jsg@xxx.edu (John S Gwynne) > Manifold question: > On the base plate there are three holes into the coolant passage. One > still has a coolant temperature sensor (CTS), another a bypass hose to > the throttle body, and the third is empty. What originally attached to > this last location? The timer/switch for the cold start injector. > Throttle body questions: > Q) I would guess the top hose connection on the right side is a for the > charcoal canister (just filtered fresh air). Correct? Filtered fresh air for the PCV system. > Q) The second one down on the right looks like a "typical" vacuum port. > Sound about right? Like Charcoal cannister purge. > Q) Now the tough one... there is a port vacuum signal near the left > throttle plate that works its way down to the bottom left of the > throttle body just behind the coolant passage. I have a hole here > with no hose barb or anything. I assume something use to attach > here; what? I don't know for sure, but the EGR system uses ported vacuum..... > Thanks for the help. You are welcome. Scot Sealander FIScot@xxx.com ------------------------------ From: pantera@xxx.com (David Doddek) Date: Wed, 31 Jan 1996 22:18:56 -0600 (CST) Subject: Re: Bosch Mono-Jetronic >At 05:09 PM 1/31/96 GMT+0200, you wrote: > >>I recently started looking at the FI system in my wife's Fiat Uno again, >>after it developed a flat spot on accellerating. >> >>The system consists of a single injector in the throttle body, an inlet air >>temp sensor, a throttle position sensor, a servo to control the throttle at >>idle (idle speed), a water temp sensor and a lambda sensor. And engine rpm >>info is sent to the system from the ignition computer. > Jim responds > What .. NO MAP sensor .. and no AIR FLOW or AIRMASS sensor??? > > are you SURE??? > It is possible to run an engine with no device at all to measure the airflow. This is how the holley projection works. It is simple. You simply measure the throttle angle and rpm and reference a map. However this map must be very accurate. It is quite commonly done on engines with little vaccume like morotcycles and highly cammed race cars. David J. Doddek |pantera@xxx.com Owner SGD Electronics & Development Engr for Caterpillar |h 309 685-7965 Formula SAE Team Sidewinder 94-95 |w 309 578-2931 89 T-bird SC, 69 Fairlane w/SGD EFI |fx 217 428-4686 74 Pantera w/Electromitive Tec-II Twin turbos and Nitros | Hey, If you are going to go fast, go REEEAAL FAST. | ------------------------------ From: wmcgonegal@xxx.ca Date: Thu, 01 Feb 96 00:43:32 EST Subject: Re: Engine codes >I can't find it, but I had a old, old, OLD mail note that said the >baud rate is 8192, and that can be obtained by changing the crystal on a old >serial port board (XT type). I have not needed to change the crystal in the computer we used to read at 8192 baud. I wrote a bit of software to program the UART (Universal Asynchronous Receive/Transmit) chip on IBM PC clones which handles the RS232 port. Unlike the inflexible DOS system for setting up the communications, through programming one can set the baud rate to a lot of different values. There are some baud rates that are close enough to be within the tolerances of reading and transmitting to a 8192 baud device using a PC. This software has worked on several different PCs from XTs to 486s for setting many different nonstandard baud rates. We did some project work on a 1989 Bonneville trying to read the engine codes at our lab. We wanted to see if we could use a PC to read the codes while the vehicle was driven (in particular we wanted speed). We have a scanner for this car. To figure out how the system worked, we tapped into the serial line between the car and the scanner and listened to the conversation with the PC. The chunks of data were displayed as bytes on the PC monitor. With the help of the scanner we determined what some of the data bytes represented. Information like battery voltage was easy to pick out (the data could come out 121 for 12.1 volts). Several of the values that were displayed on the scanner could be matched this way. The scanner could be used to turn certain engine functions on and off, and the bytes could be matched to the appropriate engine function. The location of the speed data was determined by running the car up to speed on one of our dynos and watching which value changed appropriately. Some values were read fairly directly, while others were not as straight forward (you would have to determine slope and offset, etc). There was some minor circuitry required; I believe the data signal logic was inverted for what the PC wanted. We did not need any specialized logic chips to handle voltage level shifting (the PC RS232 port is not a standard RS232 and will accept 5 volt logic levels). I do not remember all the circuitry now, but I could figure it out again (it included a 74LS05 open collector output inverter). It was a few months ago when we did this. > PS a company called DIACOM makes software that can read the serial data > and print the engine diagnostic information to a IBM PC/AT via RS232 > for $300.00 800-888-4146 Speaking from my brief experience with the Bonneville, it sounds like the DIACOM tool could be well worth the investment if you quickly want to know what is going on inside your engine control module. We only deciphered some of the data values for the Bonneville and I could see it taking a long time to figure all of them out. Of course these data values would not necessarily be the same on other models of cars. We could not have figured out what we did without the scanner. But if anyone is still interested in trying to figure out the port themselves, I can pass along the information needed to set up the baud rate and the circuitry used in the RS232 interface. Will McGonegal Electrical Engineer Mobile Sources Emissions Division Environment Canada wmcgonegal@xxx.ca ------------------------------ From: masmith Date: Wed, 31 Jan 1996 23:19:29 -0800 Subject: Re: Re: Sensor Questions? At 02:39 PM 1/31/96 +1100, you wrote: >> its hard to build a non microprocessor based fi system without >> a maf ; think about it. >> > >I disagree. It would be quite simple. >-- > Robert Dingli r.dingli@xxx.au >Power and Control Systems (+613) 9344 7966 >Thermodynamics Research Labs (+613) 9344 7712 > University of Melbourne, AUSTRALIA >** he who dies with the most toys, wins ** > i agree with the disagreement - vw built one in the 60s before uPs for the American type III market - it used an LDVT on a MAP not MAF sensor, two temp sensors (head and air) 4 injectors fired in banks of 2. for my old 70 type III, it was the most efficient (36 mpg in squareback vs 30 for lighter carb bug ) most powerful (stock of course) cleanest 1600 vw engine built for that model year. i took the controller cover off to fix a bad solder joint on a injector current limiting resistor. all discrete components.... Matt Smith masmith089@xxx.com Mailer Eudora 1.5.2 ------------------------------ End of DIY_EFI Digest V1 #28 **************************** 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".