Hi Dave,
Im unsure what you have and havent covered yourself in this topic so feel free to ask me directly what information your require.

On the Escort Cosworth most error codes are disabled with pectel software so you are out of luck with regards conventional code scanning diagnosis equiptment. To my mind, this is often due to teh software being so glitchy it was better for the tuners to remove all limp home options to save them problems when the chip caused issues and the P8 induced a 4KRPM limiter..lol.

Petrucci will tell you all about this after he drove 2500 miles for me to prove this point when my software looked crap as it wouldnt let him run over 4 but his pectel software did.... was a hard fault to find, but i found it and proved my software was just saving him from a dead engine...

My software leaves it all fully enabled and retains closed loop fuelling and knock control. With my own software id expect to see 0.4- 0.9% at idle and lambda 1 under all non boost conditions.

Common reasons for rich with P8:
Try the fuse labelled "KAT" as this is the lambda circuit, its common for this to blow as the lambdas get old and the wiring gets suspect.

Try also to borrow some NON Pectel software as teh baords can cause issues as well.

Ive subscribed to this topic now and will help all i can