Lambda Reading Lean But Exhaust Rich!?

[mhyphenl 10 1 Cars]

Hi, following on from and related to the AFM post:

 

I'm getting close, the values on the lambda are still showing lean (0.15 to 0.25 volts) but had the exhaust tested and it's still slightly rich.

 

Suspecting exhaust leak before lambda i gaffa taped henry the hoover to my exhaust and made him suck for all he was worth. Found quite a bad leak on the joint after the cat before the mid section. Got that fixed and sounds better but that wouldn't have been responsible for the mis-match in readings. Taped the vacume back on and now I can hear a leak on the flexible manifold joint, the hissing must have been masked by the louder one further down.

 

Question is, the hiss is quite audible and I can feel it if I run my finger on the underside of the flixi joint. Should this joint be air tight and how closed up should the mesh gasket be. I've put a picture below:

 

 

 

I don't know how tightly to do it up, I was worried about it not being flexible if I did it up too tight. It's quite new so shouldn't have failed in itself.

[welshpug 1,661]

the nuts go on till they bottom out, but its likely the fire ring is worn.

 

good quality kits from the dealers arent expensive

[petert 588]

Suck up 50-100mL of brake fluid into the inlet manifold if you want to find an exhaust leak. White smoke will piss out everywhere.

[mhyphenl 10 1 Cars]

the nuts go on till they bottom out, but its likely the fire ring is worn.

 

good quality kits from the dealers arent expensive

It was new 500 miles ago after rebuild. Problem is I probably didn't tighten it enough at the time and now it's goorn stiff !!

I've tightenend it further but I'm just compressing the springs, it isn't closing the gap. I've got about 6mm of fire ring showing, how much should you be able to see?