Evening all,

This car has a driveability problem which I can replicate by holding at approx 1800 rpm and after about 10 secs or so, the engine hunts badly. O2 is driven up to about 12% and HO2 sensor sticks at 0v indicating a very lean mixture. Emissions at idle are perfect. Fault codes 1510 (Idle Position Switch) and 0100 (MAF) were present and cleared down OK. PO 0505 (Idle air control) was also present but re-appears when running at approx 1800 rpm. MAF has been replaced by garage and trace is ok on both when pico'd. Disconnect MAF and problem is still there. Disconnected EGR valve and problem still there. TPS checked out ok on scanner (not scoped) going 0.9v to 4.5v with no glitches. Going back on Wednesday to have another look and check such things as fuel pressure and vacuum and anything else you could suggest. I am assuming that PO 0505 is a result and not the cause of the problem......unless someone can advise differently.

Regards

Pete M