Hi, I have recently bought a 2000 406 Exec 2.0l which is a beautiful car
and is very tidy (it was the natural replacement for my trusty 405 auto
that was recently a right off after 6.5 years). However it is not as
smooth as it should be. Sometimes (but not always) the car has a rather
rough idle which makes it feel like a diesel, it also seems sometimes to
surge and drop back in power when driving. A friend describes it as a bit
chunky.
I have had it tuned and the chap was mystified by it. Apparently the ECU
readings are all spot on, his thoughts were firstly a dirty fuel injector,
or secondly the timing belt is out or lastly but doubtfully it needs a new
coil pack.

I have since run through slick 50 fuel cleaner twice and have added slick
50 engine treatment to the oil. I have had the fuel filter replaced by my
local garage and his thoughts were a sticky rocker. Since then I have
MOTed the car at the same garage so the emmisions etc are all alright. I
find it hard to believe the timing belt is out (though I think that the
prev owner had this changed at the last service) as surely it would have
much more severe effect if this is the case. Don't want waste money on a
new coil pack on a whim - has anyone got any ideas?

Thanks in advance
Euan