DIY_EFI Digest Wednesday, 17 January 1996 Volume 01 : Number 013 In this issue: EFI articles Re: MAP sensor calibration H.E.G.O. Sources Re: MAP sensor calibration Re: O2 Sensor type? injectors Re: injectors Re: MAP sensor calibration Re: O2 Sensor type? MAP-dampening See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- From: Krister Wikstrom Date: Tue, 16 Jan 1996 14:01:54 +-200 Subject: EFI articles Hello all, Does anyone know on which issues of Circuit Cellar INK the articles on EFI were (95?)? Also (I know little about engine physics), could someone give any advice on how much the mixture can be made lean without destroying the engine. I'm talking about a project on Toyota 4x4 I'm starting. I think, that it could give better mileage, if the mixture is made leaner from normal during "steady" run? -KWi- ------------------------------ From: adh@xxx.us Date: Tue, 16 Jan 96 06:59 EST Subject: Re: MAP sensor calibration From: Donald Whisnant >From: masmith [] >any dense liquid could be used instead - the relevant factor of conversion >is density relative >to water. - the tubes will have to be longer.... >for example >motor oil - thick syrup - (anybody else got any ideas?) >even if you have to build something 10 feet high with a step ladder, its >still safer than slow poisoning. >(alternatively - build it DOWN into a swimming pool for example. >you might find it hard to buy a quart of mercury without half a dozen EPA >forms, at least in the US anyway.. [] But as you say, it is still safer and easier to use an Hg substitute and make a scale conversion. .... Try checking with Dwyer Instruments to see what substitute they recommend, I'm sure they know of one, or probably even sell one as well... .. Perhaps a glycerin compound? replacing the mercury is definitely a Good Thing [tm]. when i was a chem student, i had a professor that sprinkled sulfur powder on a fluorescent light that broke on the floor, because of the health hazard the tiny amount of mercury presented [sulfur easily reacts with mercury, and the resultant compound is a solid]. but so far all the alternatives suggested have confused density with viscosity. mercury is extremely dense - in the ballpark with lead - and has a -low- viscosity, whereas the substitutes mentioned are all close to water in density. off the top of my head, all the fluids i can think of are also close in density to water... :^< _______________________________________________________________________________ Andrew Hay LIFE, n: A phenomenon that resists the second law of thermodynamics adh@xxx.us ---Schroedinger ------------------------------ From: Paul Shackleton Date: Tue, 16 Jan 96 16:30:00 gmt Subject: H.E.G.O. Sources I realise this might be a "how long is a piece of string" question but....... In UK scrap yards, which is the best HEGO sensor to go for? (ie what make and model of car?) Best means cheapest and/or most abundant. I presume I will be able to connect it up to a standard digital volt meter to read it and will have to provide a 12V supply to heat it up? Any help will prevent endless explanations at the scrap yard. An idea of the sort of price I should be paying would also be appreciated. Paul University of Huddersfield ------------------------------ From: jzalesny@xxx.com (JimZ -92' AWD Tsi ) Date: Tue, 16 Jan 1996 10:12:59 -0800 Subject: Re: MAP sensor calibration You wrote: > >I have the response chart for a chrysler map sensors >used in turbo and non turbo models. >If anybody wants to have a free copy send me >an e-mail to >almo@xxx.mx >Oscar Alcantara Please send me a copy. Many Many ThanX JimZ jzalesny@xxx.com ------------------------------ From: robert dingli Date: Wed, 17 Jan 1996 11:44:56 +1100 (EST) Subject: Re: O2 Sensor type? > Try NGK in England they should be able to help, ask for information > on the UEGO sensor (pronounced U-A-GO). Remember I only suspected the Honda > sensor was similar (NGK say it is not the same but we have all stories like > that before). I have never been able to confirm this. Also controller for > Honda sensor appears to be in the ECU. > regards, > Mark Boxsell FWIW, I have recently bought an NGK UEGO and have the prices sitting in front of me. Sensor AUD$950, loom $120 and controller $750 ex tax. They're not cheap! I ran some calibration runs last week against an ADS9000 four gas analyser. There is some problem with the UEGO in that the voltage output wrt AFR has a 1.7V discrepency at stoiciometric and about 1.0V at the extremes of my tests (12:1 and 25:1). I'll be faxing NGK later today to find out why the output is out of spec. Robert Dingli - -- - ---------------------------------------------------------------------- Robert Dingli r.dingli@xxx.au Power and Control Systems Thermodynamics Research Lab Electrical Engineering Mechanical Engineering (+613) 9344 7966 (+613) 9344 6728 University of Melbourne, Parkville, 3052, Victoria, AUSTRALIA - ---------------------------------------------------------------------- ------------------------------ From: dzorde@xxx.au Date: Wed, 17 Jan 96 10:52:59 Subject: injectors Can standard injectors be used for NOS, or do you need special injectors with harder springs to keep them closed to compensate for higher pressures with gas ? Dan dzorde@xxx.au ------------------------------ From: Craig Pugsley Date: Wed, 17 Jan 1996 16:02:12 +1100 (EST) Subject: Re: injectors > Can standard injectors be used for NOS, or do you need special > injectors with harder springs to keep them closed to compensate for > higher pressures with gas ? > > Dan dzorde@xxx.au You can run standard injectors with 350 PSI of LPG pressure, (well, the gas is fed in from the bottom but the whole body is under presure). Injectors aren't intended to run this high pressure and it would be at just about the safety limit. I beleive you can pulse width modulate a standard N2O solenoid valve to get the flow adjustable so I suppose you could use stock injectors as the nozzles & a solenoid valve (& preferably another valve that is only on or off to stop any leakage.) Keep in mind that the flow rate will depend on the duty cycle AND the gas pressure (which varies a lot) Cheers, Craig. ------------------------------ From: dn Date: Tue, 16 Jan 96 22:01:54 MDT Subject: Re: MAP sensor calibration > but so far all the alternatives suggested have confused density with > viscosity. mercury is extremely dense - in the ballpark with lead - > and has a -low- viscosity, whereas the substitutes mentioned are all > close to water in density. For my 2 bits worth on the subject, there is no real substitute for mercury in a manometer. Motor oil is actually *lighter* than water. Mercury has a density of around 11, as I recall, while water is 1.0. Nothing else at that end of the periodic table is a liquid at room temperature. Even adding a heavy chemical such as zinc chloride to water until you get a saturated solution will only allow you to reach a practical density of about 2.0, and this stuff is nearly as nasty as mercury. Why don't you just go to your local gage supplier and get a gage calibrated in " Hg? They are not that expensive (depending on how accurate you need), and you'd have a hard time injuring yourself with one, unless you dropped it on your toe :-] Try a laboratory supply house, or an industrial gage supplier. May even be able to find something on the local surplus market. regards dn - -- ------------------------------------------------------------------------- Darrell A. Norquay Internet: dn@xxx.ca Datalog Technology Inc. Bang: calgary!debug!dlogtech!darrell Calgary, Alberta, Canada Voice: +1 (403) 243-2220 Fax: +1 (403) 243-2872 @ + < __/ "Ain't no substitute for clock speed or compression ratio" ------------------------------------------------------------------------- ------------------------------ From: mrb@xxx.au (Mark Boxsell) Date: Wed, 17 Jan 96 19:24:16 +1100 (EST) Subject: Re: O2 Sensor type? > >FWIW, I have recently bought an NGK UEGO and have the prices sitting in >front of me. Sensor AUD$950, loom $120 and controller $750 ex tax. They're >not cheap! > >I ran some calibration runs last week against an ADS9000 four gas analyser. >There is some problem with the UEGO in that the voltage output wrt AFR >has a 1.7V discrepency at stoiciometric and about 1.0V at the extremes >of my tests (12:1 and 25:1). I'll be faxing NGK later today to find out >why the output is out of spec. > >Robert Dingli >-- >---------------------------------------------------------------------- > Robert Dingli r.dingli@xxx.au > >Power and Control Systems Thermodynamics Research Lab >Electrical Engineering Mechanical Engineering > (+613) 9344 7966 (+613) 9344 6728 > University of Melbourne, Parkville, 3052, Victoria, AUSTRALIA >---------------------------------------------------------------------- > > Robert, Are yes, but is your ADS9000 correct! Four gas analysers use a "chemical cell" O2 sensor and they have a life of only about 12-18 months. Oxygen is used along with the other gases(3) to calculate the AFR so if this sensor is not reading correctly your AFR will be all over the place. The other problem is that most "cal gas bottles" do not contain any oxygen so it is hard to check. With the "firewall mounted" controller NTK only claim +/- 0.5 AFR as far as I can remember. I would be very suspicious of it being 1.7 volts out at stoiciometric that does not sound correct to me. After all it only gives a 0-5 volt output so an error of 1.7 volts is pretty bad!!!! Make sure you have enough power for the heater circuit I have run into problems with cicarette lighter plugs ie. dirty contacts, etc. The early controllers could drive a meter movement directly however the later type which you have cannot, so make sure you are not "loading" the output. High impedence input or build yourself a voltage follower op-amp to give it some grunt! Also it is very sensitive you can watch each cylinder's gases coming down the exhaust pipe if you hang a scope off it! Also do you have the correct output table ie. volts to AFR. Also 25:1 is a bit on the lean side of things to be testing spans. Quoted scale shows 10:1 - - 22:1 so 25:1 is really pushing it. 14.7:1 AFR = 3 volts. 10:1 AFR = 1.7 V 22:1 AFR = 2.65 V Hope this helps, Mark Boxsell MRB Design Sydney Australia Fax (02)629 4796 (International 61 2 629 4796) ------------------------------ From: Tommy.Palm@xxx.se Date: Wed, 17 Jan 96 09:53:44 +0100 Subject: MAP-dampening Hi! I have a question concerning MAP-sensor signal shapening. I have done a = couple of home made FI systems during the last 10 years with success. My last p= roject has a standard absolute airpressure sensor from motorola (MXP200AP) that= is very quick. I have no experience in signal shaping of the jumpy idle pre= ssure of the engine. My earlier EFI's has had std air flow sensors so i have n= ot met this problem before. The only hint i have concerning dampening in MAP se= nsors is the old Bosch D-jettronic that has a flap valve with a small restrict= ion that opens big when pressure differens gets high to aviod slow responset= ime. My question is if i shold dampen the sensor pneumaticly or only electronica= lly = (excuse my bad english). The advantidge with mecanical is more safety ag= ainst destroying the sensor with pressure peak if backfire accurs. The sensor = have a maxpress of 10 bars (145 PSI) and a linear output between 0-2,5 ATM (practical). The engine is a 2.1 lit Volvo turbo with maxboost of 1.5bar (21 PSI) so= backfire can get rather nasty if they accour. I preffer mild cams so the= idle roughness is as on a standard engine. Power > 260hp. The processor (ST6) is rather slow and the A/D has no sample-hold. Conve= rting time is 70 microsek. I have not had any indications yet that it's too sl= ow. Does somebody have any hint on witch way too go concerning dampening w/o= too slow response from the MAP-sensor? Thankfull for any help! Tommy Palm tommy.palm@xxx.se SWEDEN ------------------------------ End of DIY_EFI Digest V1 #13 **************************** 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".