Mikesidey1gmail.com Posted March 10, 2015 Share Posted March 10, 2015 Hi all, I have had a diagnostic carried out on the 2.8JTD in my Hymer Exsis and it shows a faulty turbo pressure sensor. Am awaiting a quote for a replacement. Apparently it's located behind the engine and so knowling the inaccesibility issue with the Exsis, this could be a costly repair. Has anyone had such a problem in any type of Motorhome and if so what was the cost please? Cheers Mike. Link to comment Share on other sites More sharing options...
euroserv Posted March 12, 2015 Share Posted March 12, 2015 Hello Mike, I must have missed this one the other day, so apologies for being a little late! I fear that the diagnostic device is being a little misleading, and this is all too common. It has intercepted a fault code that has a generic number and tried to describe the fault as best it can. The 2.8JTD is a (beautifully) primitive design and unlike a lot of other turbo diesels it does not have a turbo pressure regulator. The device that you are probably looking for is a manifold air pressure sensor (MAP) and this is pretty much the only component that could produce this fault code on this engine. You are definitely in the right area though because this device is screwed onto the top of the inlet manifold and even with the legendary Hymer limited access; this should not be too difficult to get at. It may have become caked up with grime and could possibly only require cleaning with brake cleaner before re-installing. If you do need a new one they are about £80 from Fiat and should be obtainable at motor factors for about half that much if it has had it. Availability should be good as the same unit will be common to many vehicles; I believe it is a Bosch item. I should say that we have NEVER needed to replace one of these in 15 years of maintaining Ducato's so you are making history here.....I would carefully check the wiring in the near vicinity though! A word of warning about fault codes though.... just because a device has reported anomalous readings does not necessarily mean that it is itself at fault. Let me provide an example; There is a stream flowing past your house and you have a water level sensor and a water speed sensor measuring water flow. If you find that the water flow is showing a lower reading than expected this could be because the flow OR level sensor is faulty. It could just as easily be because there is reduced water flow or level though. You would need to check further upstream to find out if there are any obstructions or diversions in the stream. A check of the actual level would assist in your diagnosis no end! In the same way; a sensor fault in your inlet manifold may be warning you that there is insufficient pressure and this could be because of a lack of vacuum (split in pipe) or a lack of response from the turbo (waste-gate actuator stuck) or a number of other possible scenarios but these would normally be accompanied by a serious lack of power or excessive smoke from the exhaust. The bottom line is that diagnostic equipment is useful as a guide but rarely points directly at the source of the problem. You did not say why you felt the need to carry out a diagnostic check but since you did not mention a lack of power; and the excellent record that these sensors have; I would doubt that it is at fault and would suggest that more investigation could be required. Hope this helps and please let us know how you get on. Nick Link to comment Share on other sites More sharing options...
Mikesidey1gmail.com Posted March 13, 2015 Author Share Posted March 13, 2015 Thanks for your input Nick. The reason for having the diagnostic check carried out was that I had the engine remapped about a year ago using the Quantum tuning system. The performance improvement has been fantastic with much more power and better fuel consumption. However when I use the engine under full power for more than a few seconds the red engine symbol warning light comes on on the dashboard which the users manual says is to do with the fuel injection system. The guys that did the quantum tuning remap carried out the diagnostic which led to their believing that the turbo pressure sensor is faulty. When the warning light comes on and you then take your foot off the accelerator and then re-apply the power, there is a power drop off. I do have a small amount of black smoke appear in the exhaust when the engine is warming up and I pressed the accelerator. But when the engine is warm this disappears. Other than the guys at quantum tuning, I have no idea where to take the vehicle for further checks. Can you possibly help here? Cheers Mike. Link to comment Share on other sites More sharing options...
Mikesidey1gmail.com Posted March 13, 2015 Author Share Posted March 13, 2015 PS to my last message. When the lack of power I described a curse, the engine appears to reset itself after about 30 seconds and I can then get full power again until the cycle re-occurs. Cheers Mike Link to comment Share on other sites More sharing options...
euroserv Posted March 13, 2015 Share Posted March 13, 2015 There you go Mike, I believe this makes my point very nicely. Assuming that there are no other faults with the engine (which you just have to do sometimes) and we suspect that it is the MAP sensor that is causing the light to come on..... we can; from the description of the modifications that you have had done, deduce that there is probably nothing wrong with the sensor. It is seeing a lower or higher air pressure than it is expecting and is quite correctly reporting this to the ECU and the ECU is backing off the power to prevent damage from occurring. I would fist remove the sensor and make sure that it is clean. When we are happy with that being clean or replaced, try the vehicle again. If the situation improves for a while we can assume that the modifications are causing excessively oily/sooty conditions in the manifold and this will continue to be a problem in the future. If there is no improvement at all we can assume that the re-tuning is too extreme and needs to be dialled-back a bit. To extract a little more power from a turbocharged engine is quite easy and re-mapping will often suffice. To increase the power by more than 20% or so will normally require improvements in air flow, cooling and fuelling. Any mis-match or deficiency in these areas will cause a bottle-neck and starve the engine of something that it needs; it will have to protect itself if it can. A significant increase in power will normally entail changes to at least some of the following items; Intercooler Intercooler pipes Air filter MAP sensor Wastegate control device Air flow meter If the modifications are properly done the device that is installed will have the ability to inject alternative signals to the ECU to keep it happy with the sometimes unsettling readings that the various sensors may be seeing in order that everything keeps running under the higher power conditions. A simple re-map will not be able to do this. I believe that if this sensor was not throwing a wobbly and the ecu therefore backing things off; you would be at the helm of a rapid but ultimately short-lived vehicle. Heat will kill the engine and under the bonnet of your Hymer; lots of other things too! If these people know what they are doing, tell them to reduce the power to something more reasonable and get it done soon. Link to comment Share on other sites More sharing options...
valleyboy62 Posted April 13, 2015 Share Posted April 13, 2015 I to had the same fault and followed this with interest had a fault read out done and it reported pressure sensor fault read the thread again and again and came to the conclusion it must be the sensor £53 Amazon changed still the same?? changed the air filter same fault. Decided to track down some real local diagnostic expert after a scary moment on motorway when passing a lorry and engine goes into limp mode I had got used to this light coming on and tended to disregard it backed off throttle light goes out carry on as normal. Found a firm in cardiff who had the equipment to checkout engine and before he had even pluged in test equipment told me it had been remapped I was about to tell him it was remaped when I bought it he said he could tell by the tick over he ran his dianostics and found the turbo pressure to be set way to high and unfortunately not adjustable on the programe that had been used he disscused the problem with me and it was decieded to remove the remap and install one he had took van down Dorset cost easter weekend some good hills and not a problem I do notice a slight difference in performance but not a lot to worry about as I allways said to people it was to fast and with it going into limp mode a safety issue. I hope my expriance will help the post above Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.