166 TS running problems -Help Help !!!

posted a few related threads on this forum, basically I have a 2000 166 Lusso twinnie, that runs like a dog...well perhaps that's a bit harsh, but I'm starting to get really hacked off with it. It has what I can only describe as a vibration through the rev range, and it sounds like there is a hole in the exhaust (there isn't and I have had a new manifold as this was what the local Alfa independent thought it was -on removal it was slightly cracked around the weld, but wasn't the problem!). Sounds louder/worse under heavy acceleration, or especially when having to work harder, ie hill climb etc. The vibration has been getting worse, so I had an examiner run, which showed up nothing. The garage guy said it might be the cam belt/tensioners or balance belt/shaft, but I don't see how that would make it sound as if there was a hole in the exhaust. Another independent that I tried for a second opinion said that it might be a faulty butterfly in the inlet manifold (???), but again to me these seem like stabs in the dark. I've already spent £350 having it NOT diagnosed, so am reluctant to keep chucking money at it. Anyone got any suggestions as to either what it might be or how I can find out what it is. Could it be plugs, coil packs, the inlet manifold, lamda sensor etc???/. I would have thought that if it was any of these it would have shown up on Examiner...or maybe not? HELP PLEASE....apart from the noise and vibration it runs and accelerates fine and MPG is about right at 26-31 dependent on how hard I drive. I have repaired the large split in the air-box flex coupling and checked over everything else I can. It's a shame because the rest of the car is in exceptional condition

what ever it is, it probably has Bosch written on it.

Its really hard to offer advice on a forum when even two experts and a diagnostic check have not identified the cause.

I would be tempted to unplug each sensor one by one and see if they make a difference, if it does, its not at fault, if it does not that's a starting point, problem is if its mechanical that procedure will do little and may confuse a subsequent diag check.

Does it come and go (electrical) or is it always there (mechanical)?

if the engine is noiser than normal it sounds more than just a sensor....could be the timing out a wee bit? Or the balance belt on wrong? Dissapointing that your garage can't help...whatever happened to good old mechanics who could pinpoint exactly what was wrong in 5 mins

I was thinking of a misfire causing the vibration, or the belt(s) have slipped.

My daughter Bravo sounded dreadful until the crappy Bosch coil was replaced, down to two cylinders and not detected on a £5000 diagnostic machine at a specialist. Grrr.

I had this vibration problem in my 166TS 2000. It was the cambelt idle wheels and tensioners. The vibration came back through the accelerator pedal. After being done, totally different car.
The noise could be a seperate problem.
Is it due a cambelt change. If not get a mechanic to at least pull off the covers and have a look at what is going on and check belt tension.

Best of luck

MFK

Have you checked that the spark plugs are all tight? I had a problem on a twinny once where someone had cross threaded a plug. The noise started off as a ticking at first, like a noisy tappet, and gradually got worse over a couple of weeks until it sounded like the exhaust was blowing. Eventually the car started running on 3 cylinders and sounded like a tractor. I ended up getting a thread repair done on the head. (This can be done with the head in situ before you worry too much)

Its a easy thing to check so it may be worth a look. You can check the coils are not damaged or cracked while your in there.

Simon.

Does it sound like a diesel when you start it ? Poss cam timing solenoid fault if so... The variator may be adjusting the timing in an erratic sense