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Car Forum / Citroen Cars / May 2006Veggie oil and HDi don't mix
Had a distressed e-mail. Thanks to the discussion here about vegetable oil a Xsara HDi has received a 50% mix. It won't start. I have advised to get the mix out of the tank and refuel with normal diesel. I also told to use the hand pump to get the diesel to the engine. Later on I realised that the hand pump probably won't help a lot since there the diesel can't go anywhere. Anyone knows where to disconnect the fluel tube from the engine so to refill with regular diesel? I vaguely remember during the discussion something about HDi and why vegetable oil won't work in those but I can't find that part of the discussion. Anyone?  Signatured:J0han; Certifiable me http://www.aacity.net Citroen Newsgroup Random sigs should be banned from Usenet > Had a distressed e-mail. > Thanks to the discussion here about vegetable oil a Xsara HDi has [quoted text clipped - 11 lines] > vegetable oil won't work in those but I can't find that part of the > discussion. Anyone? I don't read the discussion, but I wouldn't try this mix because HDi works at much higher pressure than old diesels, vegetable oil probably has different viscosity, density, compressibility than diesel fuel, and I don't think the engine is so tolerant to these changes as the older engines. The reason it isn't starting, I guess, is the lower compression ratio of the HDi engine compared to prechamber diesel engines. A more conservative mix (less veggie oil) could have let the engine started... I was reading <news:44718b5a$1_2@x-privat.org>, made by the entity known as Gasket, that requests spam to be sent to <gplgasketANDACAGA@hotmail.com> and I became inspired, >> Had a distressed e-mail. >> Thanks to the discussion here about vegetable oil a Xsara HDi has >> received a 50% mix. >> It won't start. >> I vaguely remember during the discussion something about HDi and >> why vegetable oil won't work in those but I can't find that part [quoted text clipped - 11 lines] > conservative mix (less veggie oil) could have let the engine > started... I found this [1]. It states "[...CDI; HDI...] These systems currently can only be converted with two tank conversion systems as they have to start up on diesel." and "additional pumps need to be fitted" It's not clear about the reason why. Could be the pump or the viscosity (or both). [1] http://www.rodbowen.co.uk/daniel/dieselengines.htm Signatured:J0han; Certifiable me http://www.aacity.net Citroen Newsgroup Changing life, Breaking ground For what it's worth, this is what I posted a while ago. My mate bought a brand new Peugeot HDI diesel about six months ago. Yes I know that this was petrol rather than cooking oil, but it's my guess that the same thing would happen, as the engine will run quite well on the cooking oil, it's only the emmision control eleky bits that dont like it. Being used to petrol he was carefull for about a month, then got slack, he put £20 worth of petrol in the near empty tank, after realising what he had done, he filled to the brim with diesel. Driving home he made it about 6 miles, this probabally being the filter full and the lines, then the car just stoped! no noises or stutters, he says it was just as if the ignition was turned off. He tried to start it but no go. Then came my phone call, I went out and pulled him home. We drained out the tank, lines and the filter bowl, Re filled with with fresh deisel and it started first turn of the key, not what I was expecting. Using this car as a taxi, he has now done about 20'000 trouble free miles in it. So it wont allways balls the engine up. My only thoughts are that the electric probes and magical bits envolved with the modern common rail engines, picked up the wrong signals from the exhaust and shut the engine down. Waddaya think???????? Regards Slim I was reading <news:1148318609.883464.249070@y43g2000cwc.googlegroups.com>, made by the entity known as Slim, that requests spam to be sent to <martin.taz@tesco.net> and I became inspired, > So it wont allways balls the engine up. > My only thoughts are that the electric probes and magical bits > envolved [quoted text clipped - 3 lines] > > Waddaya think???????? Sounds good. But I don't think the signals are from the exhaust but from the internal workings of the "common rail". I guess it reads pressure and gives volume. With the increased viscosity it reads high pressure and gives no volume but the nozzles can't deliver to the engine. I agree that it's probably a sensory mix-up, protecting the engine. Signatured:J0han; Certifiable me ( change dot com to .com to reply ) http://www.aacity.net Citroen Newsgroup The only thing that got me thinking along the electrical line, is the fact that the car has a cat and a lambda probe. The exhaust gas oxygen sensor (EGO or O2), or lambda sensor, is the key sensor in the engine fuel control feedback loop. The computer uses the O2 sensor's input to balance the fuel mixture, leaning the mixture when the sensor reads rich and richening the mixture when the sensor reads lean. Lambda sensors produces a voltage signal that recognises the amount of unburned oxygen in the exhaust. An oxygen sensor is essentially a battery that generates its own voltage. When hot (at least 250 degrees c.), the zirconium dioxide element in the sensor's tip produces a voltage that varies according to the amount of oxygen in the exhaust compared to the ambient oxygen level in the outside air. The greater the difference, the higher the sensor's output voltage. Sensor output ranges from 0.2 Volts (lean) to 0.8 Volts (rich). A perfectly balanced or "stoichiometric" fuel mixture of 14.7 parts of air to 1 part of fuel gives an average reading of around 0.45 Volts. That is how the petrol version works, I guess it wont be much different for tractors. Regards Slim > The only thing that got me thinking along the electrical line, is the > fact that the car has a cat and a lambda probe. [quoted text clipped - 22 lines] > Regards > Slim modern hdi control systems are horrednously complicated with all manner of feedback and open loop control systems in play. Actually you'd be surprised how many 'dumb' look-up tables are used (rather than feedback systems) which require many calibration maps etc and will be very sensitive to gross differences in fuel characteristics. With the advent of OBD (on board diagnostic) systems for Euro 4&5 emissions levels etc things will only get worse and you can expect your car not only to detect the wrong fuel, but refuse to start, lock the doors, book itself into the garage, call the inland revenue and inform the thought police ... <awaits knock at the door...> http://www.ricardo.com/engineeringservices/engine.aspx?page=lightdutydiesel http://www.ricardo.com/engineeringservices/controlelectronics.aspx?page=onboardd iagnosticssoftware > The only thing that got me thinking along the electrical line, is the > fact that the car has a cat and a lambda probe. [quoted text clipped - 22 lines] > Regards > Slim Yes, that's how a lambda sensor works in a petrol engine. However the probe on the cat/filter in the diesel exhaust is a heat sensor, used when burning off the particles collected in the filter. I was reading <news:caa2707bca1b490f616301eef6e63276@nntp.aacity.net>, made by the entity known as 2Rowdy, that requests spam to be sent to <Harry131313@gmail.com> and I became inspired, > Had a distressed e-mail. > Thanks to the discussion here about vegetable oil a Xsara HDi has [quoted text clipped - 3 lines] > diesel. > I also told to use the hand pump to get the diesel to the engine. Update, <quote> I started off by emptying the tank of approx 35 litres of the veggie oil/diesel mix with a garden hose and drill pump, removed and cleaned out the filter which was relatively simple by removing two bolts, one electrical plug and three quick release fuel pipes. I then moved on to remove and clean the thin metal pipes to the glow plug/injector locations. I removed and cleaned all of the black plastic pipe connections from and to the pump and filter. Filled the car up with 20 litres of pure diesel then popped an electric blow heater under the bonnet for approx 45 minutes aimed at the fuel rail. The car kicked into life after three long ingition attempts. </quote> The wise lesson. No veggie oil in HDi's. Signatured:J0han; Certifiable me ( change dot com to .com to reply ) http://www.aacity.net Citroen Newsgroup > <quote> > I started off by emptying the tank of approx 35 litres of the veggie [quoted text clipped - 16 lines] > > The wise lesson. No veggie oil in HDi's. No, just not too much. I suspect that in this case, all the veggie went to the bottom of the tank, and did not have time to mix, so the pump pulled up neat veggie oil. I was reading <news:e%Tdg.676$xH1.440@newsfe3-gui.ntli.net>, made by the entity known as Brian, that requests spam to be sent to <blecnospam@tesco.net> and I became inspired, >> The wise lesson. No veggie oil in HDi's. > > No, just not too much. I suspect that in this case, all the veggie > went to the bottom of the tank, and did not have time to mix, so > the pump pulled up neat veggie oil. If I read the link correct [1] it won't start using vegetable oil. Once it's running it can be switched to 100% verggie oil provided there are some additional pumps installed. Could well be that with a better mix the engined would have started but I wouldn't take the risk. [1] http://www.rodbowen.co.uk/daniel/dieselengines.htm Signatured:J0han; Certifiable me ( change dot com to .com to reply ) http://www.aacity.net Citroen Newsgroup > I was reading <news:e%Tdg.676$xH1.440@newsfe3-gui.ntli.net>, made by > the entity known as Brian, that requests spam to be sent to [quoted text clipped - 13 lines] > > [1] http://www.rodbowen.co.uk/daniel/dieselengines.htm That might be one way round it but I think that it is the viscosity of neat veggie oil which is the problem. If it is heated enough first, then you get round this, so all you need is a good heat exchanger, see http://www.bio-power.co.uk/exchanger.htm There is a host of information on the bio-power site. http://www.bio-power.co.uk/index.htm |
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