I've been checking this car over for a while trying to get to the bottom of why it won't rev up. The symptoms appear to be fuel starvation. There are no fault codes stored and all engine management data looks fine apart from the lambda reading which goes very lean when its rev'd. The engine ideals perfectly and the emissions are fine at idle.

I've checked manifold vacuum (17 in/hg) and checked cam timing just to be sure. I've also checked exhaust back pressure which is fine.

A rather crude test involving squirting petrol down the air intake when trying to rev does make the engine pick up, so I'm pretty happy that this is a fuelling issue.

Fuel pressure is correct at 3.5 bar and this doesn't drop when trying to rev. I've removed and checked the fuel pump pick up filter which is clear and there is now inline fuel filter fitted. I want to carry out a fuel flow test but can't find any data as to what I should expect to see. Can anyone enlighten me?