whilst drivin my car it loses all acceleration it does not stall sometimes I can retrieve power by pumpin the accelorator and get a puff of black smoke out of the exhaust and away it goes like a rocket other times im not so lucky ive had it into the fiat dealer who tried 2 charge me £85 to tell me i put bad diesel in it but if i wanted to pay £300 for a full diagnostic they would mend it HELP!!!!!!!!!!!!!!!! please

john, May 2009

EGR, Overboost and MAF sensors are all common issues with the 1.9JTD engines both alfa and fiat.

by the way, I'm an auto electrician of 7+ years :D

car_spark, June 2010

I had this problem and it turned out to be a faulty egr valve

phil, February 2010

Overboost valve is below nearside front headlight. It is a known problem and is easily moved away from moisture and water from the road. I bolted mine to the battery tray on advice from a very helpful fiat dealer. If in doubt they are not that expensive and simple to change, if a bit difficult to get to you may need to move the air filter casing. took me about 45 mins.

maxjazz, November 2009

I have the exact same model/age Fiat Stilo multiwagon. I have experienced a number of similar incidents with my car - suddenly experiencing a drastic reduction in acceleration & power for no apparent reason, accompanied by the engine fault warning light coming on. The problem normally resolves itself by the next day, although it has occasionally taken a little longer.

I did have a (cheaper) diagnostic carried out at a local Fiat dealership. They told me that the engine needed a new "Turbo overboost valve". I mentioned this to my local garage who do all works on the car for me & they weren't really sure what this was.

Anyway, I have not had anything done to resolve this and decided to live with the problem. To be fair it has not happened for many months now and I found it normally happened in a period of sustained damp weather (This may of course be entirely coincidental),

Stephen, May 2009