DIY_EFI Digest Thursday, 25 July 1996 Volume 01 : Number 209 In this issue: Re: Throttle Pos sensor vs. MAP/MAF Re: DIY_EFI Digest V1 #207 Re: DIY_EFI Digest V1 #207 Re[2]: Spark Advance Engine POWER! Re: EFI control units Re: water injection questions Re: water injection questions??? Turbo maps? Bosch D-jetronic schematics? RE: EFI control units Throttle Body Sizing Re: Water injection questions Re: Throttle Body Sizing Re: spark advance curve modification Re: water injection questions??? [admin] volunteer needed Re: water injection questions Re: water injection questions??? Re: spark advance curve modification Re: Filtering supply lines RE: EFI control units Re: Throttle Body Sizing Re: EFI control units See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- From: ricrain@xxx.net (Ric Rainbolt) Date: Wed, 24 Jul 1996 04:54:53 -0500 Subject: Re: Throttle Pos sensor vs. MAP/MAF >In looking at the engine as an air flow circuit, I look at the throttle as >an impedance, a fairly constant pressure outside, MAP pressure inside, >another impedance (valves etc.), and a vacuum caused by engine at a certain >speed. > >The thing is, temperature/external pressures aside (which have to be catered >for anyway even when measuring air pressure/flow), > >For a given engine at a given speed, doesn't one throttle position map to >one pressure? I understand there can be some lag; but MAP sensors aren't >instantaneous in reading anyway. > >I understand that pressure readings may harken back to the days of vacuum >advance in old distributors; but, temperatures aside, would a throttle to >RPM lookup be any different to a Pressure to RPM lookup in any situation? > > To not have a MAP/MAF sensor at all would be quite interesting. Such changes as ring wear, valve lash, dirty air filter and barometric pressure would throw the car off the theoretical air table. Speed density (MAP, Tach, TPS) systems can run without MAP in a fall back mode, though the implementations I've seen run rougher and less fuel efficient. The Bosch systems I've played with (2.6) run undetectably the same with just the TPS disconnected... strange. Also, in this group (or was it EFI332?), there has been alot of discussion on MAF vs. Speed-Density. My personal preference is the latter and it should be pointed out that the highest specific output engined car ever sold in this country (at 162 BHP/L) used a Speed-Density system. Throttle response was excellent and the car was able to fully meet Kalifornia emissions laws. Of course, it got crappy milage. :-) The high end car modifiers that I've dealt with all use Speed-Density, and this probably has more to do with my descision... at least if I have problems, I can take the car to them to get fixed. Seems that the act of "calibrating" a MAF sensor for an application is just as much of an effort as "mapping" an engine using Speed-Density. Oh, well. I'm about to find out since I'm mapping my first engine in about 3 weeks. I'll only be getting 136 BHP/L after its all broken in, though. ;-) Ric Rainbolt ------------------------------ From: talltom Date: Wed, 24 Jul 1996 03:16:07 -0700 (PDT) Subject: Re: DIY_EFI Digest V1 #207 Can anybody come up with a diagram for a d-jectronic brain used on a 72 mercedes 280 sel 4.5? I just Inherited the thing and now that I own it, it's gotta run right. It's down to 4-6 cylinders and hopfully a friend who understands electronics has said he might help figuire it out. Yes I know it's brain dead. ------------------------------ From: talltom Date: Wed, 24 Jul 1996 03:16:05 -0700 (PDT) Subject: Re: DIY_EFI Digest V1 #207 Anybody out there got any info on the ishi turbo #'s rho5 spec vb1 exh.housing #p21oR and a rhb5-311a? The first one came in a kit that said Spearco on it, Mr. Spears, any ideas? compressor maps, any info would help! ------------------------------ From: jfaubion@xxx.mil (jfaubion) Date: Wed, 24 Jul 96 09:14:19 cdt Subject: Re[2]: Spark Advance Engine POWER! > Also, for peak power and > performance, the vacuum and centrifugal advances should be in good working > order and should advance the spark under load or RPMs. However, in > American cars, the vacuum advance is (and has been since about 1972) a > vacuum *retard*. This does reduce NOX emissions but it is detrimental to Actually most American cars DO have vacuum advance. The main purpose of the vacuum unit is to allow the engine o start with a modest amount of advance to reduce the loading on the starter motor. Once the engine fires and manifold vacuum builds it advances the timing to ensure a smooth idle. When you open the throttle plates, manifold vacuum drops, and this will effectively retard the timing but this helps prevent knock. When the vacuum drops in a wet flow manifold the fuel can deposit on the manifold walls and will cause a momentary lean condition until the fuel from the accelerator pump can arrive. This would cause knock if the timing were not retarded. Once the engine speed increases the mechanical advance comes in which compensates for the loss of advance from the vacuum unit. Some cars do use a dual canister vacuum unit to provide the advance using ported vacuum which basically does the same job as the mechanical advance. Those vehicles that use it usually have either no mechanical advance or a small amount of mechanical advance. John Faubion jfaubion@xxx.mil ------------------------------ From: Fred Miranda Date: Wed, 24 Jul 1996 08:01:03 -0700 Subject: Re: EFI control units At 10:04 PM 7/23/96 -0700, you wrote: >I'm very new here--just been reading this group for a couple of >weeks--and have a question or two on available control units. I've been >sorting out what I think I need to convert Triumph six-cylinder to >digital FI, but have not yet found a control unit which seems to meet the >requirements I've set. > >I'd like to find a controller with sequential injection and is also >programmable via laptop and can accept input from a domestic MAF sensor. > >I realize many of the folks here are concerned with building their own >control units and doing much or all of their own programming, but I >simply don't have the time or test equipment for that sort of >undertaking. > >Any suggestions? >Thanks. > Electromotive TEC2 and maybe Motec ------------------------------ From: Wayne Braun Date: Wed, 24 Jul 1996 09:10:22 -0600 Subject: Re: water injection questions At 10:18 PM 7/23/96 -0700, you wrote: >> | Just a cautious thought out of the blue (i.e. I don't know the >> | answer) ... it might be a good idea to check on the corrosiveness >> | first, especially if you have aluminum heads. Any chemists out >> | there? >> | Anthony Tsakiris >> | >> >> This topic came up on the hotrod list some time ago. the peroxide you buy >> in the store is too dilute to do any good. Anything stronger is very >> corrosive. Apparently peroxide was used as rocket fuel a long time ago. >> >> --steve > >Quite correct, Steve. The use I remember is in the Messerschmidt ME-163 >rocket plane. As I recall, pure H2O2 is a sufficiently strong oxidizer >that it can burn skin on contact. There were problems with tank >integrity in the planes, and they occasionally leaked. Made for an >unpleasant flight, from the pilot interviews I've seen. >Cheers. > A couple of years ago I was at the Canadian Aviation Museum in Ottawa, they have ( had ) at least 2 of the ME 163 Comet aircraft. In the discussion, it was mentioned that the plane used H2O2 as the oxidizer for the fuel. Apparently, pure H2O2 dissolves animal matter ( animal matter being things like flesh ). Due to the tank integrity problems mentioned, landings tended to be somewhat exciting. It is the only aircraft that is known to have MELTED its pilot on landing. From what I can remember, they lost as many pilots landing the plane as in combat ( or something like that ). The moral of the story is that one should be VERY careful when using H2O2 especially if it is concentrated. Regards Wayne Braun ------------------------------ From: ptimmerm@xxx.GOV Date: Wed, 24 Jul 1996 08:50:23 -0700 Subject: Re: water injection questions??? >If all a person wants to do is lower the heat of combustion and hence the >speed of the flame front, then why not just fatten up the fuel curve at the >point where detonation is expected? Why add all the extra hardware and >expense (and risk) of a water injection system? Water does do more than just cool it. I think the original post said that cooling was the major effect. I would not argue that point. I will again add that steam is an anti-detonant, and that you can run much higher boost levels without detonation with water or water methanol than with fuel enrichment. There is a big difference. I seem to remember numbers like 10% higher cylinder pressures without detonation with 50/50 water methanol. The other point to be repeated is that most of us don't have unlimited fuel delivery capability. And since you dont need to enrichen the mixture with water present, you can run stronger without leaning out. This is a big deal with OEM turbo fuel injected apps. Stepping down from soap box. Personally I don't run it so that will blow up if I run dry, and there is still a big effect. But I also run intercooler sprayers at the same time. they both have very nice effects (measured). paul timmerman ------------------------------ From: talltom Date: Wed, 24 Jul 1996 10:38:34 -0700 (PDT) Subject: Turbo maps? > >Anybody out there got any info on the ishi turbo #'s rho5 spec vb1 exh.housing >#p21oR and a rhb5-311a? > > The first one came in a kit that said Spearco on it, Mr. Spears, any ideas? >compressor maps, any info would help! > > > ------------------------------ From: talltom Date: Wed, 24 Jul 1996 10:35:36 -0700 (PDT) Subject: Bosch D-jetronic schematics? > >Can anybody come up with a diagram for a d-jectronic brain used on a 72 >mercedes 280 sel 4.5? I just Inherited the thing and now that I own it, it's >gotta run right. It's down to 4-6 cylinders and hopefully a friend who >understands >electronics has said he might help figuire it out. Yes I know it's brain dead. > > > ------------------------------ From: "Orin Harding" Date: Wed, 24 Jul 96 14:15:48 UT Subject: RE: EFI control units Mike, I have been using the TEC II made by Electromotive on my '79 MGB and it works well. This ECU provides not only fueling control but also direct ignition control. The coils are supplied with the ECU and you do away with all of your old distributor, etc. You'll have to mount a crankshaft timing wheel, probably on the harmonic balancer, and sensor. Other sensors are water temp, air temp, throttle position, O2, and MAP or MAF sensors. There is an output to control a GM style idle air control motor. The biggest drawback to this unit is it's cost. Basic ECU for 6 cyl, with no sensors, is $1030.00 and the software another $300 to $500 depending on which version you get. To use a MAF sensor you'll need the $500 version. Sequential injection is available for an additional $250. I have tried both MAF and MAP and found that MAP was a lot easier to install and get running OK. You'll find that MAF sensing adds to the overall system hardware complexity especially the intake. You have to be very careful not to have any air leaks at any point after the MAF sensor with straight runs of pipe upstream and downstream of the sensor. As I said, MAP is a lot easier. If you're not in a hurry, I've found a unit in England, currently under development, that should sell for about $1000 and will have the same features as the TEC II plus adaptive fuel control. I'll be seeing the manufacturer next month and hope to bring a unit back with me then. I'll post a note here regarding the unit. - ---------- From: owner-diy_efi@xxx. Porter Sent: Wednesday, July 24, 1996 1:04 AM To: diy_efi@xxx.edu Subject: EFI control units I'm very new here--just been reading this group for a couple of weeks--and have a question or two on available control units. I've been sorting out what I think I need to convert Triumph six-cylinder to digital FI, but have not yet found a control unit which seems to meet the requirements I've set. I'd like to find a controller with sequential injection and is also programmable via laptop and can accept input from a domestic MAF sensor. I realize many of the folks here are concerned with building their own control units and doing much or all of their own programming, but I simply don't have the time or test equipment for that sort of undertaking. Any suggestions? Thanks. ------------------------------ From: "Orin Harding" Date: Wed, 24 Jul 1996 15:37:48 -0400 Subject: Throttle Body Sizing While trying to decide on the proper size throttle body for my MGB EFI project, I found the following formula for determining carburetor air flow requirements in "Auto Math Handbook" by John Lawlor: CFM = (RPM x displacement) / (2 x 1728) For my 1.8 L (110 ci) MGB engine this works out to be about 191 CFM at 6,000 RPM. OK fine. A 40 mm ( about 1.5 inch) throttle body should pass about 200 CFM with 10 inches water drop. Well I thought, this couldn't be right as the pre '75 MGB's had twin 1.5" carbs. and the later cars had one 1.75" carb. What gives here guys? To further this thought, shouldn't the intake valves duration somehow be included in this? Granted the engine may only need 190 CFM but the throttle body needs to pass this amount of air during the intake valve's open time so the actual sizing of the throttle body would be much larger in order to pass the required amount of air. Here is what I think sizing should be based on. I've used my MGB's cam data in this example: 1) Peak RPM: 6,000 2) Engine CI Displacement: 110 3) Intake valve duration (Deg): 252 4) Time for 1 crank revolution: 0.01 sec. (60 sec / RPM) 5) Time for 1 deg. of crank rotation: 2.381E-05 (#4 / 360deg) 6) Intake time per 4 cycle period: .006 seconds (#5 x #3) 7) Intake time per minute: 21 seconds (#1 x #6) 8) Engine CFM requirement @xxx.8 CFM ((#1 x #2) / 2) / 1728) 9) Estimated Throttle Body steady state flow requirement: 636 CFM (60 sec./#7) x #8 Well, if you assume that the engine has a VE of about 65% at 6,000 RPM then the throttle body needs to be sized for about 413 CFM. This is just about what two 1.5" carbs. will pass (steady state) which is what was used on the pre '75 MGB's. This makes me think that my assumptions are correct. Hopefully one of you will have an answer to this. ------------------------------ From: "Tony Bryant" Date: Thu, 25 Jul 1996 08:43:16 +1200 Subject: Re: Water injection questions > > How much benefit might be produced in a non-turbo, stock motor. I'm think purely > of the charge cooling and increased charge mass. Could this produce significant > gains used with enrichment at WOT? Roughly how much water would be required per > volume of air? How much ignition advance would be required ? > I haven't experimentally verified it, but my simulations tell me that the presence of water has the effect of cooling the peak cylinder temperatures. In other words some energy that is normally going into driving the piston, is now heating up some water. i.e. less power because your engine is now becoming a petrol powered steam generator, instead of an engine. Excess fuel does exactly the same thing (which is why it helps prevent knocking), fuel may be more expensive than water, but the fuel injection hardware is already there. IMHO the only use of water injection is cooling the intake charge, and even then a cold air/ram air box & a decent or no filter is probably more effective. As for volume of water & advance, I can't help.... *********************************************************** * "Insanity is the only sane response to an insane world" * * >> bryantt@xxx.nz << * *********************************************************** ------------------------------ From: Markus Strobl Date: Wed, 24 Jul 1996 16:57:02 -0500 Subject: Re: Throttle Body Sizing > While trying to decide on the proper size throttle body for my MGB EFI > project, I found the following formula for determining carburetor air flow > requirements in "Auto Math Handbook" by John Lawlor: > > CFM = (RPM x displacement) / (2 x 1728) > > For my 1.8 L (110 ci) MGB engine this works out to be about 191 CFM at 6,000 > RPM. OK fine. A 40 mm ( about 1.5 inch) throttle body should pass about 200 > CFM with 10 inches water drop. Well I thought, this couldn't be right as the > pre '75 MGB's had twin 1.5" carbs. and the later cars had one 1.75" carb. > What gives here guys? > > To further this thought, shouldn't the intake valves duration somehow be > included in this? Granted the engine may only need 190 CFM but the throttle > body needs to pass this amount of air during the intake valve's open time so > the actual sizing of the throttle body would be much larger in order to pass > the required amount of air. [snip] The formula you quote is correct. It assumes 100% VE. In the real world it seems most engines prefer slightly larger carburators than the formula indicates. For instance: a 350 cid V8 w/ 6000rpm redline would need a 610 cfm carb. Yet most built 350s run better with 750 CFM carbs. My guess is this is the result of how the carbs are rated (ie the pressure drop used to rate carbs is larger than is optimum for engine power). A single 40mm TB sounds alittle restrictive for your application. But you won't flow over 500cfm, like you calculate. I don't know enough about MGs to recommend a specific size TB. Just as a comparison, my 5.7l V8 uses twin 48mm TBs w/ 5800rpm redline. Markus ------------------------------ From: Dig Date: Wed, 24 Jul 1996 17:21:32 -0500 Subject: Re: spark advance curve modification > I have a turbo car (8.7:1 compression, 91 octane required) with a GMP4 > ECM. I KNOW where the spark curves are on the eeprom, my question is: > > can someone give a description of a baseline tequnique i can use to > modify the spark table for "mild/medium" performance increase? What kind of a powerplant is it? (4-cyl, v6, ?) I do some chip twiddling on a 4.3 turbo V6... (GMP-4) > example: increase advance for the lower load lines 1-2 defress, and the > upper load lines 3-4 deg, or increase beginning of all lines 1 degree, > middle of lines 2-3 degrees and ends of lines 1-2 degrees.. Let me preface this by saying that the following assumes you have an increased fuel capacity or better octane or better intercooling (or all the above)... Your timing table is set up as an absolute MAP vs. RPM vs. timing, no? With a turbo, you'll want to add more timing at low MAP (~100 KPA abs.) and low RPM (600-2000) to get the turbo to spool up a little quicker. Avoid big jumps at high load (170-180 KPA abs.), you'll end up getting a lot of detonation. A lot of this tuning is best done by adding timing slowly, and watching to see what effect this will have on knock retard. Keep in mind that shifts in ambient temp will effect this dramatically, you'll see much more knock on a hot day. I'd try to bump up the ESC attack rate for the testing period, so that if knock does occur, timing will be taken out quickly. Might also want to bump up the max retard parameter to allow more timing to be taken out. Personally, I'm of the mind that performance increases should be acheived via increased boost and *decreased* timing. It's tough to determine where the decreased timing will hurt you more than the increased boost gains you, however. > engine is MAP controlled, not MAF and HAS ELECTRONIC SPARK CONTROL with > knock sensor.. can i rely in knock sensor to protect against possible > over-advance on eeprom if i accidently use a "FA" insted of "2A" ? As long as you keep a close eye on knock retard during your test runs, you should be ok. You'll hit the max retard limit set in your ECM, which should tell you that you've got a little too much timing somewhere. Do you have a 2-bar MAP, or a 3-bar? What's the service # on your ECM? Dig dig@xxx.edu ------------------------------ From: "Robert E. Yorke" Date: Wed, 24 Jul 1996 15:46:31 -0700 (PDT) Subject: Re: water injection questions??? Paul: What kind of setup do you use for your "Intercooler sprayer"? Is it some form of spray applied to the internal water conduits inside the body of your intercooler (I assume you're referring to an air-to-water vice air-to-air intercooler). Could you please provide the results of your measurements of improvement? I'm using an air-to-water intercooler, mounted in the trunk to keep it away from the heat (It's a Fiero), and while that necessitated a little extra length to the air ducts, it hasn't caused any noticeable delay in the onset of boost. The reservoir tank is in the trunk too, with a marine pump at the bottom driving water from the tank to the intercooler to a motorcycle radiator back to the tank. During boost the delta T is around 60 degrees; with some needed insulation for the intercooler-to-throttle body tube it may get a little better. With some form of sprayer, it may get a lot better.... At 08:50 AM 7/24/96 -0700, you wrote: > > Snipped >Water does do more than just cool it. I think the original post said >that cooling was the major effect. I would not argue that point. >I will again add that steam is an anti-detonant, and that you can run >much higher boost levels without detonation with water or water methanol >than with fuel enrichment. There is a big difference. I seem to >remember numbers like 10% higher cylinder pressures without detonation >with 50/50 water methanol. The other point to be repeated is that most >of us don't have unlimited fuel delivery capability. And since you >dont need to enrichen the mixture with water present, you can run >stronger without leaning out. This is a big deal with OEM turbo >fuel injected apps. Stepping down from soap box. Personally I >don't run it so that will blow up if I run dry, and there is still >a big effect. But I also run intercooler sprayers at the same time. >they both have very nice effects (measured). > >paul timmerman > > Riverside, CA 2 '88 GTs! ------------------------------ From: John S Gwynne Date: Wed, 24 Jul 96 20:27:37 -0400 Subject: [admin] volunteer needed There's that ugly word again... volunteer. I need someone, for about three months, to take over the day-to-day task of managing the mailing list request that for one reason or another don't get resolved automatically. The volunteer can easily do this maintenance remotely through email. Working knowledge of Majordomo would be helpful but not necessary. It's really just a job of unsubscribing mail that bounces and rerouting posts that get sent to the wrong address or that are too long. Your cooperation is appreciated.... (don't make me ask twice :). 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: FIScot@xxx.com Date: Wed, 24 Jul 1996 22:39:53 -0400 Subject: Re: water injection questions In a message dated 96-07-23 18:46:17 EDT, you write: >How would GM EST react to this situation? On my 89 TPI set up, I noticed >that after running high octane fuel for a week and then switching to the >cheap stuff, if I floored the throttle I would hear a few detonations and >the check engine light would come on. Code 43 EST. After two or three times >of this, it would start working normally. Does it take the ECM this long to >adjust. > >GMD No. The ECM does not adjust (as in learn) at all in this application. But it should not get the error code 43. Is the wire shorted? This error would indicate one of two things. Either it never knocks, or it senses knock all the time..... Scot Sealander FIScot@xxx.com ------------------------------ From: pantera@xxx.com (David Doddek) Date: Wed, 24 Jul 1996 21:43:00 -0500 Subject: Re: water injection questions??? Here is my 1/2 cent worth. Water injection does more than just help to retard detonation. Someone worried about it taking away heat from the combustion and wasting power, but remember when water turns to steam it also expands, A LOT. This makes for higher combustion pressures, the steam also cleans out the carbon from the cylinders which helps to further reduce the chance of detonation. And besides the increase in combustion pressure comes in the form of average pressure and not peak pressure. Higher average pressure is not as hard on the engine and results in greater HP increases. And water injection does work. I had a friend with a Mustang SVO that was a factory turbo test car from Warner Ishi. If he pulled the waste gate hose off it would run at 25 psi of boost. It would also start do detonate at 3000 rpm to the point that it would cause the car to jerk voilently. With injecting a small amount of water, he could run full boost all the way up to red line and toast the 8 cylinder guys. He just used the boost pressure to pressurize a tank of water and dump it through a small adjustable valve into the turbo inlet. Trial and error found the right amount of water. He did not even use a nossle. Just dumped it into a vacuume hose port before the turbo. The spinning turbo atomized it. On another theme, adding extra fuel will not reduce knock by a significant level. I have a fuel computer that I have made that has the main fuel adjustable. I have a 69 ford 302 with 9:1 and without good fuel it will knock like a pig. I have accelerated with a good power mixture and experienced knock. While accelerating I have turned the fuel up to the point that the engine was loosing power and rolling black smoke. Guess what, the knock was still there. However making the mixture even a little leaner would result in knock increasing rapidly until it sounded like a machine gun. So the moral is more fuel will only get rid of a tiny amount of knock at the best, but fouls plugs, washes cylinders, looses power and gets lousy fuel econemy. All of this is from experience and not an uneducated opinion. To address the worries about running out of water, use a sensor in the water tank to determine empty. Wse this to activate a solenoid valve that will either lower boost via a second setting of a wastegate or cause the diaphram of the distributor to be retarded or an input to the ECM that changes the timing curve of your custom EFI box. And besides, if water was that corrosive to the engine, why does the engine not fall apart when people live in highly humid climates like fog and rain. My car always runs better on a cold foggy day. Well, that was almost a full penny so I better quit. 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/Electromotive Tec-II Twin turbos and Nitros | Hey, If you are going to go fast, go REEEAAL FAST. | ------------------------------ From: Dave Zug Date: Wed, 24 Jul 1996 23:08:18 -0400 Subject: Re: spark advance curve modification Dig wrote: > > > I have a turbo car (8.7:1 compression, 91 octane required) with a GMP4 > > ECM. I KNOW where the spark curves are on the eeprom, my question is: > > > > can someone give a description of a baseline tequnique i can use to > > modify the spark table for "mild/medium" performance increase? > > What kind of a powerplant is it? (4-cyl, v6, ?) I do some chip twiddling > on a 4.3 turbo V6... (GMP-4) V6.. 3.1 litre intercooled. boy have I been looking for *you* > > > example: increase advance for the lower load lines 1-2 defress, and the > > upper load lines 3-4 deg, or increase beginning of all lines 1 degree, > > middle of lines 2-3 degrees and ends of lines 1-2 degrees.. > > Let me preface this by saying that the following assumes you have an > increased fuel capacity or better octane or better intercooling (or > all the above)... I *WOULD* be able to give more boost electronicly IF i could fing the 20 psi boost limit setting. I also would be able to give more fuel if i knew fuel table location. As it stands, I use 94 octane and have an adjustable wastegate rod tuned for 19-20 max on cool day. i often get injector lockout in cool fog. The wastegate is effectively delayed a shord duration allowing boost to build quickly at low rpm's.. i'd like to return the adjuster rod to factory spec and use fuel/boost tables to get performance. the GPP4 is the latest gm puts out, i think its "711". the cal-pak is double chup, one for ESC(nut eprom, a formed circuit with 8 of the 28 pins connected. the 2nd chip is a 27c256 eprom, main code starts at 2000 relative(A000 absolute) spark table is around 0108 relative or thereabouts. checksum routine is at or near ffe3(absolute) or so, end of chip. i give these references so you can see any similarities between my chip and yours.. i really would like to know those table locations!!! > > Your timing table is set up as an absolute MAP vs. RPM vs. timing, no? > With a turbo, you'll want to add more timing at low MAP (~100 KPA abs.) > and low RPM (600-2000) to get the turbo to spool up a little quicker. > Avoid big jumps at high load (170-180 KPA abs.), you'll end up getting > a lot of detonation. > yes, MAP. ok, i see. an initial increase of adding 1 degree to first 2 data, then 1-2 deg addition to next 3 settings, 3 deg to next 2, 2 deg to next 4 and 1 to remaining, as a general guide for starters. i'll watch knock signal for increases. thanks. > A lot of this tuning is best done by adding timing slowly, and watching > to see what effect this will have on knock retard. Keep in mind that shifts > in ambient temp will effect this dramatically, you'll see much more knock > on a hot day. if i overtune and get excessive knock on hot day, but dont want to (or can't) change chip, will an octane booster help temporarily? > > I'd try to bump up the ESC attack rate for the testing period, so that if > knock does occur, timing will be taken out quickly. Might also want to > bump up the max retard parameter to allow more timing to be taken out. again.. table/data locations?!?! can you send a copy of a dump of your 4.3 GMP4? i'd gladly trade you for mine, i guarantee that *NO* "performance" chip maker makes one for me, 2 months research, and is the reason for me getting into this! glad i did. > > Personally, I'm of the mind that performance increases should be acheived > via increased boost and *decreased* timing. It's tough to determine where > the decreased timing will hurt you more than the increased boost gains you, > however. point taken. limiting factor for me is that pesky injector shutdown routine at 20 psi! plus the boost being CONTROLLED to 15 psi. > > > > engine is MAP controlled, not MAF and HAS ELECTRONIC SPARK CONTROL with > > knock sensor.. can i rely in knock sensor to protect against possible > > over-advance on eeprom if i accidently use a "FA" insted of "2A" ? > > As long as you keep a close eye on knock retard during your test runs, > you should be ok. You'll hit the max retard limit set in your ECM, which > should tell you that you've got a little too much timing somewhere. got it. > > Do you have a 2-bar MAP, or a 3-bar? What's the service # on your ECM? > > Dig > dig@xxx.edu i have the factory unit from GM. i have seen items referencing a "better" map sensor, have not investigated details. Looks like you can help a poor information-starved tech-hobbiest like me out alot! anything you can offer would be great! the car is an 89 grand prix turbo. it can be seen in detail at: http://www.ssnet.com/~advpower/dzug/89gpturbo.html check it out and send a feedback form from there if you want. click on the driver's door TURBO emblem to see another "hidden" car. thanks for the time! ------------------------------ From: Darrell Norquay Date: Wed, 24 Jul 96 20:39 PDT Subject: Re: Filtering supply lines At 02:14 PM 7/24/96 +1100, Stuart Woolford wrote: >> The only way to guarantee you are at a true 0v ground is to run >> a wire back to the battery terminal. > >and what defines the battery terminal as 0v ground? The battery is the "power supply" for the entire electrical system. I think it was mentioned earlier that both the supply + and ground be run back to the battery. This helps in several key points: *The battery is extremely low internal impedence, and tends to "short out" high frequency noise. *The battery acts as a large capacitor, absorbing both voltage spikes and supplying heavy load currents for short periods of time, and tending to average out the system voltage. *The alternator is theoretically connected essentially directly to the battery, therefore absorbing most alternator noise. >really - the battery terminal can be a particularly noise prone >ground point depending on the charging system design.. (from too much >car sterio install experience..) If this is the case, then the battery ground lead should be repaired or replaced. Any voltage drop from the battery to the chassis will affect ALL devices attached to the chassis. In my car I have separate 2Ga ground leads going to both the engine and the frame directly from the battery. This alleviated a lot of noise problems I was having with the stereo. Most grounding problems occur due to "ground loops", where there are several different paths back to the power supply (battery) from different devices within the car body. Each of the paths has a different finite resistance, and current flowing through them will generate a voltage across each of these resistances. This is what causes ground noise. In an ideal world, every device in the whole vehicle would have it's own separate ground wire running directly back to the battery, then any noise or voltage drop generated on any given ground lead would have no effect on any other lead. Unfortunately, this is not the case, and auto manufacturers rely on the assumption that the body itself is a single homogenous conductor, which unfortunately it is not. The best you can hope to do is isolate your particular installation from the rest of the system by running it's own power and ground leads directly to the battery. There is one caveat to this approach - you must ensure that your ground lead is the ONLY path back to the battery from your system, if there are any other "hidden" connections to chassis ground from the installed equipment (ie a radio chassis or speaker - lead), all bets are off, you've now created a ground loop instead of eliminating one... >looking for a 'true' ground is usually not the solution, finding a >non-noisy one is quite a different job - I have usually found a good >solid frame ground to be good - you pick up so much noise on you >earth line to the battery that it gets real bad real fast. You just >need to find a frame ground with good conduction paths to the other >ground references you are linked to. This is the standard method, unfortunately it is an approach that masks the symptom rather than cures the disease. Sometimes it is the only thing you can do, to avoid, as you said, bad charging system design. Grounding and ground noise is a whole black art unto itself. regards dn dnorquay@xxx.com ------------------------------ From: John Dammeyer Date: Wed, 24 Jul 96 23:17 PDT Subject: RE: EFI control units At 02:15 PM 24/07/1996 UT, you wrote: > >I have tried both MAF and MAP and found that MAP was a lot easier to install >and get running OK. You'll find that MAF sensing adds to the overall system >hardware complexity especially the intake. You have to be very careful not to >have any air leaks at any point after the MAF sensor with straight runs of >pipe upstream and downstream of the sensor. As I said, MAP is a lot easier. I'm quite new to the fuel injection scenario too. What is MAP verses MAF and what type does a SAAB have? Thanks, John. Pioneers are the ones, face down in the mud, with arrows in their backs. Automation Artisans Inc. Ph. 604-544-4950 6468 Loganberry Place Fax 604-544-4954 Victoria BC CANADA V8Z 7E6 ------------------------------ From: John Dammeyer Date: Wed, 24 Jul 96 23:17 PDT Subject: Re: Throttle Body Sizing At 03:37 PM 24/07/1996 -0400, you wrote: >While trying to decide on the proper size throttle body for my MGB EFI >project, I found the following formula for determining carburetor air flow >requirements in "Auto Math Handbook" by John Lawlor: > >Well, if you assume that the engine has a VE of about 65% at 6,000 RPM then >the throttle body needs to be sized for about 413 CFM. This is just about >what two 1.5" carbs. will pass (steady state) which is what was used on the >pre '75 MGB's. This makes me think that my assumptions are correct. > What is VE ? Thanks, John. Pioneers are the ones, face down in the mud, with arrows in their backs. Automation Artisans Inc. Ph. 604-544-4950 6468 Loganberry Place Fax 604-544-4954 Victoria BC CANADA V8Z 7E6 ------------------------------ From: "Michael D. Porter" Date: Wed, 24 Jul 1996 21:49:16 -0700 Subject: Re: EFI control units Orin Harding wrote: > > Mike, > I have been using the TEC II made by Electromotive on my '79 MGB and it >works well. This ECU provides not only fueling control but also direct >ignition control. The coils are supplied with the ECU and you do away >with all of your old distributor, etc. The biggest drawback to this unit >is it's cost. Basic ECU for 6 cyl, with no sensors, is $1030.00 and the >software another $300 to $500 depending on which version you get. To >use a MAF sensor you'll need the $500 version. Sequential injection is >available for an additional $250. > I'm a bit confused--I received literature from Electromotive about three months ago on precisely the unit you describe, and there was no mention whatsoever of sequential injection, and, to boot, the schematic included clearly showed what I generically describe as L-Jetronic injector wiring (two injector pulse lines from the ECU, each feeding three injectors, and then spliced together to pulse all injectors once a rev). I did very much like the integrated crank-fired ignition (and the ability to do even rudimentary curve-mapping on the basic unit is helpful), and thought (except for the price) that it was altogether pretty slick. But the planned duration and overlap is just to enough to require (I think) sequential, and assumed from the literature that it wasn't available, so I just kept on looking. How recently did you buy the unit you're now using? > I have tried both MAF and MAP and found that MAP was a lot easier to >install and get running OK. You'll find that MAF sensing adds to the >overall system hardware complexity especially the intake. You have to be very careful not to have any air leaks at any point after the MAF sensor with straight runs of pipe upstream and downstream of the sensor. As I said, MAP is a lot easier. >The decision of MAF in favor of MAP is based mostly on reading incidental articles which suggested that MAP has some of the behavioral characteristics of carburetors, in that it can be fooled at some combinations of gas speed and inlet air density. My general neighborhood has an altitude range of about 9-10,000 ft in a three-hundred mile radius, and after driving a few domestic rental cars which had the check engine light dancing on and off up and down hills, and listening to people complain about how often the MAP sensor failed, I thought it best to put up with the additional design difficulties. I am aware of some of the difficulties of getting proper air flow through the sensor--Donaldson came up with a particulate trap system for diesel engines which used, in part, a Ford MAF sensor, and we did have a time translating the requirements of that sensor to the production line. Once the optimum position was found, we had to mark all the boots and pipes with witness lines so that each bus would go together reliably. > If you're not in a hurry, I've found a unit in England, currently under > development, that should sell for about $1000 and will have the same >features as the TEC II plus adaptive fuel control. I'll be seeing the >manufacturer next month and hope to bring a unit back with me then. >I'll post a note here regarding the unit. >Thanks, Orin. In truth, I feel in a desperate hurry, but the reality is otherwise; the cars are in storage until I get a shop built, and I'm right in the middle of remodeling the house, as well. Soooo, practical wisdom tells me I've got a bit of time yet. I've just been doing what I can to finalize all the bits and pieces of the system so it will work together properly. Cheers. ------------------------------ End of DIY_EFI Digest V1 #209 ***************************** 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".