New owner, rough idle, black smoke, hesitation - help/ideas needed please!
Hi everyone, I'm hoping to call on your collective experience and expertise. I'm 4 weeks into owning a 2007 A4 TDI 170 s-line quattro special edition. Great car, big improvement on my previous A3 but from day one I've experienced a problem that has yet to be solved.
- Rough/lumpy idle (intermittent), jumps between 900 and 1000 rpm
- Engine shakes when idle is rough
- Black smoke (excessive) - both on idle and under acceleration, chokes cyclists who get overtaken
- Hesitation/flat spots - particularly in 3rd gear, at low revs, but car pulls well at high revs to the red line
- All appear when engine cold or hot
- No warning lights show (like DPF, check engine)
- No error codes
Fixes/inspections so far
- Audi garage ran diagnostics, no error codes, say nothing wrong with car on a test-drive, confirmed injectors had been replaced under the recall 18 months ago, weren't interested in problems
- Independent garage run full diagnostics, no error codes, but thought it may be egr cooler. Ran overnight pressure test, said engine/injectors were fine but cleaned manifold out, said it needed a 'good run down the motorway for a few hundred miles (the dealer I bought it from arranged all of this and weren't tech-minded so I'm not sure what 'manifold' he cleaned but he spent a day looking over it, told them if the problem persisted he could do a 'de-coke')
- I dumped a can of BG244 into a full tank of V-Power to see if it would make any improvement (mpg seems to be better)
. . . but the symptoms are still there. The dealer I bought it from did go out of their way to help, taking it to Audi and, not satisfied with their explanation, taking it to another independent specialist because they could see the symptoms and thought it wasn't quite right. However, all say there's nothing wrong with the car but I refuse to believe it as extensive google searches bring back lots of cases of similar symptoms but few solutions. The dealer I bought it from were really helpful if severely lacking in mechanical knowledge so wouldn't question any hypothesis thrown at them by a mechanic and aren't very local to me so I'd prefer to arrange any further investigations myself.
Any ideas, anybody?!
The other thing I've seen is a few companies doing re-map, DPF delete and EGR delete specifically on the TDI 170. Has anybody had this done and is it a potential solution?
Thanks in anticipation.