Alfa 156 JTS missing power
Hi have a 2005 (late facelift - registered April 2005) 156 with 2.0 JTS engine, with 97000 miles. Compared to my previous early 156 TS, it has never been as free revving. Now I know all the stories about the shortcomings of the JTS, the different character, the coking of inlet valves - but mine is a late one, with the altered gearing and cam timing that was supposed to prevent the coking problem. Does it really?
Anyway, problem is this - the car pulls really well low down - way better than the TS. But it never has that 3000+ rpm shift when the TS had its power kick in - in fact it's hard (and a bit pointless) to get it to rev over 5000 - it is just flat.
I have plugged FiatEcuScan in and had a look around. No fault codes. From the Actuators section I can make the VVT solenoid click (and tried switching to a known good one off my TS). Have tried swapping the MAF sensor, and spark plugs. Absolutely no difference. With the engine running, FES shows zero ignition advance - I have seen that reported elsewhere - but could that be a factor, or is it just a bug in the software?
I also tried driving with FES running. Floored it at 2000rpm - somewhere around 3000 the VVC flag went to ON - but returned to OFF shortly after - not sure when but certainly well before 4000 (with no obvious change in engine performance). Is this normal - or could this be a clue to the problem? Any other suggestions, please?