Initial complaint was intermittant idle hang at 1200RPM or so. (Which I am now thinking is a symptom of the underlying mixture prolem rather than a fault in itself)

However scan revealed P0170 fault logged. Mixture is lean and "Missy" at all speeds with Lambda signal indicating lean however a squirt of carb cleaner/easy start generated an immediate Lambda switch to rich.

No other fault codes logged.

Archive check doesnt seem to reveal any similar problems

Now...

1) The Lambda sensor seems OK from above test.

2) EGR valve seems OK, I could operate it manually (By sucking on the vac tube) and hear the engine note change. And a small bypass leak that would cause a miss at idle should not make a big diference at higher speeds (I imagine)

3) I have scoped the MAF and it seems a good crisp trace peaking at around 4.5V. Dsconnecting the MAF doesnt make a big diference but it does seem to run a little better with MAF disconnected.

4) no sign of air leaks (like with the old mondeos) and in any case, an air leak that woulds cause a miss at idle would be unlikly to cause a serious weak condition at higher speeds.

5) the car seems to drive OK (at least OK enough not to have caused concern that something might be wrong) so I would be surprised if it were down to fuel supply problems. Though a faulty FPR delivering reduced fuel pressure could conceivably be causing a problem. I have not yet managed to test fuel presure however, that is on the list for when I get back (Do these have a shraeder valve port for checking fuel rail presure? I couldnt find one and the supply pipes dont look easy to get at unless I go back to the filter)

6) Live data reveals "Credable" values for air and water temperature as it does for throttle position.

At this point I ran out of time. Now, for when I go back, what have I missed??

I have read that the ecus sometimes develop earth fauts such that the signal received by the ECU is lower than that generated by the MAF (But I would have thought that disconnecting the MAF would give a big improvement in this case) so that might be one to look at more closely. Any other suggestion??

PAul