My 2006 VW Jetta TDI has started to shudder a little when quickly accelerating, puts out more black smoke during this, and the fuel mileage has dropped a few mpg. It doesn’t accelerate like it did previously. The VW dealer replaced the fuel filter but not much changed. VW tech support suggested replacing the fuel filter again, replacing the fuel injectors which would cost around $2000 and said that they were not sure that would fix the problem. Is there some fuel additive that could clean the clogged fuel injectors? By the way, the car is 12yrs old with 177,000 miles.
With that kind of mileage, I’d suggest maybe you’ve worn out the camshafts. I had a friend have this problem.
Not sure if you’ve had an actual mechanic look at the car or if you are just getting advice from the VW tech line, but I’d suggest getting a mechanic to actually diagnose the problem in person.
if you have mechanical skills, you can change the fuel injectors on your own; many youtube videos on how to do it; sounds like you don’t have the skills; go to yelp and get bids from several independent repair places; the fuel injectors are the likely problem; the guy who talked about the camshaft is 99% probably wrong; don’t waste time with those gas additives; your car is too far gone for that; once you get new fuel injectors; add a can of that additive stuff to a full gas tank about every 5000K miles; with the mileage you have, it will need it
Possibly clogged injectors, turbocharger bogging down, or compression dropping.
When I worked for VW and an engine problem existed we always ran a compression test right off the bat. If there’s a serious engine issue it’s best to discover that immediately before spending a lot of money on things that may not be needed.
Unless things have changed, and if the compression was good, we would then test the injectors. VW dealers have (or had… ) a bench tool for testing injector pop-off pressures and spray patterns.
If there was an issue the injectors were rebuildable on the spot. I’ve done many of them.
Understand that I haven’t worked for VW for close to 20 years so maybe their methodogy is different now. Hope that helps in some small way.