Hi, I have a Zafira 2.2 Auto which used to go very well. It has now done 80K miles. Over the last two years its performance has dropped. Last year, after 3 expensive visits to my local dealer, the EGR valve finally developed a fault and was replaced. That made a slight difference, but since then the performance has continued to deteriate. This year, the new EGR valve failed too, and it was replaced. Yet again there was a slight improvement but the overall progress is downward.
Although I think that the car is a bit slower off the line than it used to be, the main change is above 3000 rpm. The car used to have a lovely surge of power around 3000-3500 rpm but that has all gone. Overtaking used to be a joy, now it is just a memory! I did some acceleration runs, videoing the speedo, and then stepped through the frames to plot an acceleration curve. This showed that my maximum power was about 80 bhp at 4000rpm and it dropped to less than 60bhp at 5500rpm instead of rising to 145bhp as it should.
With the car being an auto, this makes it difficult to drive - if the engine is labouring on a motorway hill then giving it a bit more throttle makes the gearbox change down to where it expects there to be more power, but there isn't and the car slows even more!
The dealer can find nothing wrong and, because the car drives okay at low speeds and with only moderate throttle, then they think I am imagining the problem, but I'm not. I live near Bristol and there is a 'steep' motorway hill on the M5 on my way to work. I used to be able to accelerate from 90 to 100 going up the hill before, but now it slows from 90 to little more than 80 instead.
Apart from the poor performance, the car seems fine - it starts fine, idles well, pulls smoothly without any hiccups or stutters, doesn't use excessive fuel.
Does anyone have any ideas? Could it be a blocked cat?