AFR all wrong

[S-Express]

On a recent rr session, my afr dipped under 11.0 at 3200 rpm and kept falling to 10.0 at 5800 rpm.
I've also noted that tail pipes are pretty sooty looking....
I've got a homefry and a decent exhaust system.
No ecu faults.
Cleaned + checked MAF.
Lambda only done about 7k miles.
Clean air filter.
Samco hoses - don't think I've got a boost leak as gauge reads 1.4bar. (could be a small leak I suppose)
So what could be up? MFTS? anything else worth checking?

cheers fellas

[Rusty]

Could still be a boost leak. Get it checked properly as even the Samcos can leak at the joints I had a Samco delaminate where the jubilee clip went on, didn't casue boost cut but my AFRs were as bad as you describe. Fixed the problem and AFR is now a steady 12 or so.

[Rusty]

With boost leak



Without boost leak

[S-Express]

Thanks Andy, looks similar to mine, I'll have to get my compressor out of hiding then!

[Rusty]

Something I always try to do before anything important is a boost leak check... shame to waste £50 on a RR session to find that something's leaking. BTDT a few times.