Engine Performance problem
2003 Volkswagen Passat 4 cyl Two Wheel Drive Manual 122000 miles
My car throws out black smoke when accelerating. It seems to be significantly doiwn in MPG also and there seems to be s light loss of power. Turbo does not seem to be packing the punches. Have had the diagnostics run on it and the only thing that showed up was the "Coolant Temp Sensor". Have replaced this and no better. Have changed where I get my fuel - no better. Have added an engine cleaner to the fuel - no better. Also have another problem which is while accelerating the car vibrateds like mad and it comes up through the gear stick. Have diagnosed this to be the Dual Mass Fly Wheel. A problem I could do without. But the black smoke is really annoying me. Any ideas? Have read in otehr forums that the EGR valve gives trouble but should this not show a fault code on the diagnostics equipment? Any ideas? All suggestions welcome!
Your turbocharger bearings are probably shot and a new set of bearings or turbine shaft will be needed. The black smoke is most likely burning oil out of the turbocharger and would explain the black smoke on acceleration. Make sure of this by doing a compression test on the cylinders.
June, 23, 2008 AT 4:26 AM
My mechanic has had a look at the turbo. He didnt see anything obvious. There was no oil in the bottom of it which was what he was expecting to find. Turbo appears to be working but not at full capacity. He checked the fuel system also and all looked normal there. Only thing that hasnt been checked are the injectors. Its a pain. I have very little patience for these sort of problems. Never had any bad experiences with 9 years of volkswagon cars. This is the first to give trouble. Thanks for your feedback. You could be right though about the turbo bearings. But would it not be completely flat to drive?
June, 23, 2008 AT 1:34 PM
Your tech probably will not find any oil residue on the turbocharger. Your talking about a leak that might only occur at several hundred RPM. Is there lateral and end play of the turbine shaft? The only other possibility is the timing chain or belt. It might be worn badly enough that the tensioner inside does not keep the slack out of the belt causing it to change the timing slightly under acceleration. It is possible that the computer is not changing the timing properly which could be caused by low boost from your turbo or a problem with the CPS sensor. Try to see how the car behaves without the turbocharger and leave the exhaust uncapped. It will be loud but can rule out several problems depending on what you experience.
June, 24, 2008 AT 1:15 AM
Have recently replaced Timing Belt, pulley, PS belt and AC belt. Its also had full service. So your probably right. If timing was out it would be more noticeable. It doesnt seem to be out at all. That side of things seem fine. It probably is turbo. Thanks ever so much for your help. It just seems to be Ã Ã Ã Ã Ã with this car at the minute. Thinking of changing it after I get all fixed. Before something else goes wrong. Any known faults / issues with the Audi A6 2.0TDI say 2006 or 2007 model?
June, 24, 2008 AT 10:38 AM
No problems that I know of. A6 recieved top honors in Car and Driver the past couple of years.