Flat at 2500-3000 RPM

Morning All,

2000 Vogue 4.6 Petrol

When accelerating, the rangie goes flat at around 2500 RPM then picks up again around 3000 - 3500. In effect its as if its losing power. It works normal around the other RPMS. Also, have noted in the mornings of late, that she can be a mare to get rolling, ie, put foot down and nothing until at least 30 seconds of moving, even had a slight misfire pop out the back as well.

I had the IAC off yesterday and gave a good clean and the throttle body (TB) seems fine and not full of buildup witht he butterfly feeling fine and not sticking, the throttle cables for throttle and cruise control are good and the connections to the TB are now clean.. MAF was cleaned a little while back and looks fine, and the boots are all ok with no splits.

Any ideas.. Just seems weird that the issue is only around that RPM...


Thanks

Tricky one without some live data recording what the O2 sensors are doing. Chances are it is the O2s or the MAF playing up.

rewmer said:

Tricky one without some live data recording what the O2 sensors are doing. Chances are it is the O2s or the MAF playing up.

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2nd id

I replaced the O2's post CAT about a month ago and no change. Also, it initially failed the MOT on the emissions, hence changing the O2's and this bought the figure down but still high for fast idle.

TimSeall said:

I replaced the O2's post CAT about a month ago and no change. Also, it initially failed the MOT on the emissions, hence changing the O2's and this bought the figure down but still high for fast idle.

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As I understand it the UK spec should only have pre cat O2 sensors, the post sensors are for monitoring the performance of the cats when fitted. American market ?

Opps, had to go out and check, I blame Sunday mornings myself.

They are pre-cat sensors that were replaced, and your right, only the NAS market has 4 ;-)

Thanks

Tim