I have a T5 2.5 TDi 130 4motion 2005 that suddenly started to spit black smoke clouds some months ago. I took it to the garage (in two different places actually). They plugged in the computer but couldn't find any fault. Their conclusion is that it's just normal, it's an old lady, maybe i tanked up with dirty fuel, some diesel additive could help etc. I refueled many times since then, with or without additive, and this didn't really help.
After some good reading on this forum, I understood black smoke can have many origins, but a common one seems to be a leak in the intercooler or in the boost hoses that connect it to the turbo and the engine. So my question before I take it to the garage and pay for a related check: would a boost leak be fully consistent with the following symptoms?
1) black smoke appearing under load (gentle or hard acceleration, steady uphill), especially from 1800 to 2200rpm for any gear, but much less or not at all at higher rpm. If it were a boost leak, why would the air/fuel ratio become OK at high rpm, when the air pressure is a priori higher, leading to more lost air?
2) more smoke in 2nd or 3rd gear than in upper gears. The smoke in 4th to 6th gear is slightly less abundant, or maybe more grey than black (sorry for the lack of precision, these are wing mirror observations)
3) the engine judders slightly when accelerating in 2nd or 3rd from very low rpm (only up to about 1500rpm).The judder is always accompanied by a thick cloud of black smoke. This could be misfiring, but I can't tell for sure. This judder problem is quite new (2 months) compared to the first appearance of black smoke (8 months).
4) i can't feel a loss of power when accelerating. But the fuel consumption definitely went up
Something else about the age of my engine: the car clocks 170k miles but a new engine was installed at 130k (by the previous owner; due to some factory defect in the original engine, VW accepted to replace it together with free wheel).
Thanks for your insights!
After some good reading on this forum, I understood black smoke can have many origins, but a common one seems to be a leak in the intercooler or in the boost hoses that connect it to the turbo and the engine. So my question before I take it to the garage and pay for a related check: would a boost leak be fully consistent with the following symptoms?
1) black smoke appearing under load (gentle or hard acceleration, steady uphill), especially from 1800 to 2200rpm for any gear, but much less or not at all at higher rpm. If it were a boost leak, why would the air/fuel ratio become OK at high rpm, when the air pressure is a priori higher, leading to more lost air?
2) more smoke in 2nd or 3rd gear than in upper gears. The smoke in 4th to 6th gear is slightly less abundant, or maybe more grey than black (sorry for the lack of precision, these are wing mirror observations)
3) the engine judders slightly when accelerating in 2nd or 3rd from very low rpm (only up to about 1500rpm).The judder is always accompanied by a thick cloud of black smoke. This could be misfiring, but I can't tell for sure. This judder problem is quite new (2 months) compared to the first appearance of black smoke (8 months).
4) i can't feel a loss of power when accelerating. But the fuel consumption definitely went up
Something else about the age of my engine: the car clocks 170k miles but a new engine was installed at 130k (by the previous owner; due to some factory defect in the original engine, VW accepted to replace it together with free wheel).
Thanks for your insights!