[CharlesStevenson]

Originally Posted by dingov70

Morning , the quickest solution & the right one is a live data read of the engine at working temp after a run . Watching the data from the sensors tells you what is causing your errors . It is not unusual for one failing sensor to force another sensor to work outside it's programmed limits and that triggers codes incorrectly

You could also ask your MOT station if they can do an emission test to see exactly what reading the gas analyser is sampling . Faulty Lambda gives readings that wander all over the place , a failed cat will typically hold a steady CO value

We often perform this for customers who have failed emission tests , after repairs have been made

Before you leap into big money spending , check plug gaps , coil packs are fitted tight / wiring to coil pack is good / clean / secure

Taking data from the MOT test we have

Fast idle test
CO = 0.97 Not Ok
HC = 151 Ok
Lamba 0.994 Ok

Second fast idle test
CO = 0.13 Ok
HC = 62 Ok
Lambda = 1.102 Not ok

Natural idle test
CO = 5.656 Not ok

As mentioned I swapped the MAF with one from a volvo breakers and that seems a little better but the problem's not cured.

To assume that MAF was at fault too ... unlikely.

I've tried cleaning the IACV more than once but again that's only seemed to cure it temporarily, which could have simply been down to luck.

The symptoms are, lumpy running sometimes, that 'flat spot' feeling as if your pressing of the pedal's not being ignored by the fuel system and also the running on of the fan when switching off the engine. The fan issue can be overcome, most times, by starting the car, letting it run for about 10 sec & then switching it off again.

All seem to be MAF related from what I've read on here but it's all supposition really without actual data & I don't fancy paying for parts to be replaced because they 'should' cure the problem.