Thanks for the help everyone. The car is back with the old guy, as he needs it daily to walk his "HUGE" dog. He said I can have the car as long as I like when it's dead. (The dog that is )

Anyways

Nigel

The HEGO is showing a very lean voltage, during the hesitant period. This changes the instant that it clears. At 4,200 RPM it will pick up, like you have flicked a switch. It maybe something in the mapping, that causes this characteristic. What I mean is that maybe the system is designed to ignore certain parameters (such as Barometric values) at certain engine speeds & throttle openings & this maybe why I feel a sudden increase in performance at that point. (probably talking bolox again)

Darren

FMEM hey! Thats a new one on me . I will remember to throw that into a chat with like minded techs & see if I get any blank looks.

I take on board what you are saying about the inffered value, but I have a MAP style sensor fitted to the nearside inner wing that needs an explanation. It maybe something to do with the auto box I suppose. I found a passage in a tech document about what you said & it offers something slightly different.....

"""BARO must be inferred, usually at high throttle openings or is derived from a MAP/BARO sensor."""

Maybe this one does have a Baro sensor. Either way, you can bet that I will try your suggestions to see what happens.

Nick

I take your point about scoping back at the ECU. I have been caught out recently when I witnessed a good capture taken from the sensor end, only to discover a problem when looking from the ECU end. Its harder work, but ultimately more useful to do it the way you suggest. I will try harder in future .

I may not see this again for a week or two, but I need to sort it, for my own sanity.

Thanks again for the thoughts

Dave (Hill)