peter deer Posted July 14, 2012 Share Posted July 14, 2012 Hi an interesting technical question which i do not think has been raised in this forum before I'm just back from a trip to the Alps where our flat is at 2100 m (not feet! ) On the way up ,no smoke ,business as usual but on the way down ,heavy smoke when pressing the accelerator pedal ,even ever so slightly When back in town at 600 meters ,no problem again Puzzling I thought about 2 possible explanations : -oil aspirated into the cylinders through worn valve guides ?(but i would have the same smoke problem at sea level ,which is not the case )and she does not burn any oil between oil changes -not enough oxygen in the air to burn the fuel injected into the cylinders (the ECU does not know the oxygen content of the air ),which is more likely Have you had the same experience ? any idea ,advice ? Peter Ps : I also noticed a strong smell of diesel when following other ,more " modern " cars ,although woth virtually no smoke Quote Link to comment Share on other sites More sharing options...
vulcan bomber Posted July 14, 2012 Share Posted July 14, 2012 Its the latter, less air at higher altitude. Alot of vehicles have oxygen sensors to tell the ecu how much oxygen available. Quote Link to comment Share on other sites More sharing options...
JimAttrill Posted July 14, 2012 Share Posted July 14, 2012 I am permanently at 1753m (according to Wiki) and my 300tdi doesn't smoke much except when cold as the engine has done 306 000 kms. If you investigate the TD5 ECU there are a lot of things it doesn't know, like the fuel pressure for example. It does not have an altitude sensor, just boost pressure and temperature. If it doesn't smoke at sea level I wouldn't worry about it. Petrol engines have lambda sensors in the exhaust so they can adjust the mixture to keep the emissions down. The TD5 doesn't have them. Quote Link to comment Share on other sites More sharing options...
Eightpot Posted July 14, 2012 Share Posted July 14, 2012 When you're going up, the turbo is whizzing and pulling more air in. On the way down, no boost and a rich mixture due to the reduced oxygen. If you drive a non-turbo diesel up a mountain it smokes way more than a turbo charged one. Quote Link to comment Share on other sites More sharing options...
Early90 Posted July 14, 2012 Share Posted July 14, 2012 Yes i have experienced similar symptoms in my 200tdi 90. You do not say what colour your smoke was but i presume blue as you mentioned burning oil. I went to the Alps last year and spent a week driving tracks and was alarmed to find my recently fitted, just run in, Turner engine bellowing blue smoke! Mine smoked going up and going down.It smoked less when decending off the throttle and condiderably more when on it but seemed to smoke constantly.When down in a valley on tarmac there would be lots of smoke under accelaration for a K or two then clear to normal,ie no visible smoke of any colour.When we left Italy we drove around France before coming home via Calais,no smoke on the journey or since! With us was a td5 90 that smoked,a lot less than mine as the driver did not notice himself. a d2 td5 no smoke. 200tdi in a series no smoke. and a nad, no smoke. I spoke to some one who goes there every year who said he has seen it many times before and that some do it and others do not. When driving mountain tracks I did notice that, although engine revs were as for normal driving, the egt was always low and the coolant was not reaching normal temps (vdo temp gauge),apart from that no other symptoms. Quote Link to comment Share on other sites More sharing options...
peter deer Posted July 16, 2012 Author Share Posted July 16, 2012 Hi Only back to the screen now , sorry !! many, many thanks for your comments :it is good to feel you are not alone with a particular problem!!! seems to be a majority vote for imbalance between fuel and oxygen at high altitude !! BTW : good to see that the military use the good old 300 tdi in their Snatch and LR Wolf vehicles Quote Link to comment Share on other sites More sharing options...
sierrafery Posted July 18, 2012 Share Posted July 18, 2012 U could put a new AAP(Ambient Air Temperature and Pressure) sensor though...cos it's his job to compensate the altitude...u'll not know it's faulty unless u read some live data or check voltages...here is from the Workshop manual- engine management >Td5(if we speak about this one?) :The AAP sensor is located in the top of the air filter housing. It provides voltage signals relative to both ambient airpressure and temperature to the ECM. The AAP sensor produces a voltage between 0 and 5 volts proportional to thepressure level of the air in the air filter housing. A reading of 0 volts indicates low pressure and a reading of 5 voltsindicates high pressure. The ECM uses the signal from the AAP sensor for the following functions:l To maintain manifold boost pressure. l To reduce exhaust smoke emissions while driving at high altitude. l Control of the EGR system. Quote Link to comment Share on other sites More sharing options...
peter deer Posted July 18, 2012 Author Share Posted July 18, 2012 Hi many thanks for your remarks and documentation Unfortunately ,mine is a 300 tdi and I do not think there is such an AAP sensor !! Peter Quote Link to comment Share on other sites More sharing options...
sierrafery Posted July 18, 2012 Share Posted July 18, 2012 there could be some inputs missing there cos the ECM has to make corrections for the athmosferic pressure : http://landrover.workshop-manuals.com/discovery300tdi/index.php?id=315 ...IMO worth a try with an other MAF...maybe u'll see some difference Quote Link to comment Share on other sites More sharing options...
JimAttrill Posted July 18, 2012 Share Posted July 18, 2012 Lots of the AAP sensors don't work and are VERY expensive so often not fixed. Quote Link to comment Share on other sites More sharing options...
peter deer Posted July 18, 2012 Author Share Posted July 18, 2012 i am a bit lost now :do you think there is an atmospheric pressure sensor in the 300 tdi ? the extract of the manual isn't 100% clear about this ! and if I there is one ,where is it !! Peter Quote Link to comment Share on other sites More sharing options...
sierrafery Posted July 18, 2012 Share Posted July 18, 2012 No, IMO the ECM uses the MAF inputs for that Quote Link to comment Share on other sites More sharing options...
JimAttrill Posted July 19, 2012 Share Posted July 19, 2012 i am a bit lost now :do you think there is an atmospheric pressure sensor in the 300 tdi ? the extract of the manual isn't 100% clear about this ! and if I there is one ,where is it !! Peter Well, there is in a way.... The diaphragm in the injector pump has turbo boost pressure on one side and atmospheric pressure on the other side so the fuelling will vary with altitude. Though on thinking about it this will tend to over-fuel at altitude for the same boost. Though as boost pressure is the amount over atmospheric anyway maybe it won't On thinking about it the arrangement will prevent overfuelling as it automatically adjusts for altitude. I should know as I was trained in the RAF as an engine fitter but that was 45 years ago Quote Link to comment Share on other sites More sharing options...
peter deer Posted July 19, 2012 Author Share Posted July 19, 2012 not an easy question ,as i can see!! If there is some form of adjustment for air pressure in the injection pump ,would that mean that heavy smoke at altitude=faulty injection pump? or turbo boost pressure ? If the answer is yes ,what should i do about that ?parts to change ? a reminder though ,at ground level ,no problem whatsoever.On the way back from the mountains (550 miles on motorway at 55/60 max mph , she's done an exact 32mpg ,not too bad for an old (1995) lady !! Quote Link to comment Share on other sites More sharing options...
JimAttrill Posted July 19, 2012 Share Posted July 19, 2012 You can adjust the diaphragm in the injector pump - however this is normally done to increase fuelling and power. I did it to my own engine many years ago and have done it to others as well. It is best to have an EGT gauge in case you overdo it. But there is no 'easy' way of adjusting the pump when you go to the mountains. It's easy for me to keep an eye on things as I have a boost gauge - you just fit it in the line from the turbo to the injector pump, but I also have an EGT gauge which has two functions - one to set off an alarm at high temps (I have mine set at 725°c which is safe) and I never shut down the engine until it has dropped to 200°c (an arbitrary figure). With your mpg figures I think you have nothing to worry about - I also cruise quite slowly which helps a lot. I ignore the speedo and do 103 - 109kmph on the GPS. The engine 'feels' happiest at these revs. Though mine is in a 110 which has lower gearing (but bigger tyres). Quote Link to comment Share on other sites More sharing options...
peter deer Posted July 19, 2012 Author Share Posted July 19, 2012 your car is equipped like a jetfighter !! sheer curiosity ,unrelated to the subject :could you tell us more about your EGT gauge does it measure the temperature of the exhaust gas ? if yes ,where ? interesting ;more details ,please !!! Quote Link to comment Share on other sites More sharing options...
JimAttrill Posted July 19, 2012 Share Posted July 19, 2012 Here is the thermocouple but many people put it in the EGR blanking plate. I wanted it as close to the exhaust valves as I could get: and here is the furnace controller - it switches off at a set temp and I operate an alarm using a reverse relay I think the make is Shinho or Shinko made in Japan Quote Link to comment Share on other sites More sharing options...
peter deer Posted July 19, 2012 Author Share Posted July 19, 2012 an interesting idea ! could you briefly explain what deductions you make from reading the temperature levels Quote Link to comment Share on other sites More sharing options...
vulcan bomber Posted July 19, 2012 Share Posted July 19, 2012 Well, there is in a way.... The diaphragm in the injector pump has turbo boost pressure on one side and atmospheric pressure on the other side so the fuelling will vary with altitude. Though on thinking about it this will tend to over-fuel at altitude for the same boost. Though as boost pressure is the amount over atmospheric anyway maybe it won't On thinking about it the arrangement will prevent overfuelling as it automatically adjusts for altitude. I should know as I was trained in the RAF as an engine fitter but that was 45 years ago Thats wrong.... it has boost on top and a SPRING under it. There for the fuelings only affected by the boost pressure the turbo can make. Altitude doesnt come into it. The bosch VE pump can be fitted with a device called an Aneroid Compensator that controls the fueling with altitude changes, it looks and works like the boost Capsual. Quote Link to comment Share on other sites More sharing options...
peter deer Posted July 20, 2012 Author Share Posted July 20, 2012 thanks for your remark i'lll look up for your words Aneroid Compensator :this afternoon peter Quote Link to comment Share on other sites More sharing options...
JimAttrill Posted July 20, 2012 Share Posted July 20, 2012 Thats wrong.... it has boost on top and a SPRING under it. There for the fuelings only affected by the boost pressure the turbo can make. Altitude doesnt come into it. So apart from the spring, what air pressure is underneath it? Ambient, I presume. So altitude will come into it. Quote Link to comment Share on other sites More sharing options...
peter deer Posted July 21, 2012 Author Share Posted July 21, 2012 Aneroid Compensator:would it be difficult to fit such a device to the pump ? expensive ? diy possible or have it done by bosch ? Peter? Quote Link to comment Share on other sites More sharing options...
vulcan bomber Posted July 21, 2012 Share Posted July 21, 2012 Aneroid Compensator:would it be difficult to fit such a device to the pump ? expensive ? diy possible or have it done by bosch ? Peter? They cant be fitted to a pump with the boost compensator on... The aneroid compensator lives were the boost compensator lives. If your competent with dismantling the injector pump then its a DIY job. If you've had a pump to bits before then its easy. Quote Link to comment Share on other sites More sharing options...
peter deer Posted July 21, 2012 Author Share Posted July 21, 2012 i just fear this is beyond my capabilities shame !! many thanks again for your comments Peter Quote Link to comment Share on other sites More sharing options...
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