Intermitant Misfire and loss of power 156 v6
Right, I know I'm being cheeky 2nd post, but I'm desperate!
I have a x plate 156 2.5 v6 which is running again like a pig in the mud.
Problems started, in December and been ongoing for 7 weeks now, engine warning light came on and started to loss power, judder and have delayed throttle response,
Got it diagnosed as P0340.
So new camshaft position sensor duly purchased and fitted, no joy. Wrong it needed the crank sensor. So engine stripped the top and checked coil packs and plugs and all seem ok. evrything seemed to be working.
Jibbed my usual mechanic because he was struggling and took it to alfatech in Hudderfield. On the way really started to miss fire and pop. stalled, would not hold revs and then fired up again and limped there.
At alfa tech they redid all these tests, replaced the cam position sensor again. stripped the engine to check the timing had not slipped and all A1. So they got a second hand ECU fearing this is the problem.
Drove ok for 20 miles or so and then bang, same again running and missfiring, poping in the engine and power coming when it feels like. Back to the first garage and the dreaded diag, faulty o2 and faulty temperature so Lambada and MAF duly ordered. Fecking rubbish still. Next he reckon the fuel pump was weak and the thermostat was shot, so Fuel pump and thermostat changed.
Thought it was done, but not, Full ecu/throttle reset later and 25 miles of decent driving on saturday, and then back to the same problem. Noticed hole in the concertena pipe that goes between the throttle body and Maf, changed that today and another full reset seemed sorted for 5 miles and its just as bad.
£1000+ already spent and nothing resolved, if anything worse.
Forgot to mention this power lose and misfires is intermitant, one minute its not there, the next it is, also generally gone after 3500rpm, ie not to bad if you rag it.
Has anybody got any ideas at all? The only thing I can think of is, the throttle body? the throttle fly by wire system? but that would not lead to misfire would it? The top of the air filter box is loose, but that would not affect all this would it? the engine only measures from the MAF upwards doesn't it.
Thanks all, please help If I have to get a new car the wife wont let me touch another alfa after this, tough challenge this one
Last edited by Bez; 14-01-09 at 21:00.