Hi chaps
Ive got a 89 series 2 running mfi, a uknown chip and 12psi boost on standard cooler.
Ive got a hesitation/stutter on boost in 3rd 4th and 5th gear, I fitted a wideband afr gauge and my readings are

Light throttle/cruising :between 12.5-13.5
On boost :between 13.5-14.0 sometimes 14.2
When I come off the throttle the gauge goes straight to 22.9 untill it reachs about 1800rpm it then starts reading afr again

So my question is do these reading seem ok and any idea what the.hesitation could be
Ive been to 3 different tuners now and they keep taking my money and telling me its fine but it isn't
Any ideas much appriciated
Mick

 

No they aren't particularly okay

In an ideal world you would be 14-15 cruising and 13-12 on light boost.

Its okay that you go super lean when you close the throttle, the mfi flap closes and stops injecting fuel. I would take it for a set up OR as you have a wide band lambda set it up your self.

Rob,

 

Thanks for quick reply rob
So if I slightly increase my fuel via the actuator on the side of my metering unit this will increase the fuel on boost is that right bud

 

Yes it is, sadly it increased fuel pressure across the board so you will get richer off boost too but it does mean you will be nice and safe on boost.

5th injectors are a great improvement as you can back the fuel pressure off (to get a nice 14-15 idle) and use the 5th injector to richen up on boost.

Rob,

 

Thanks rob
Ill have a gentle tweak and see if it does the trick,i take it its clockwise for more fuel then ill set my base idle/ co to around 13afr 3.6co as it is now

Thanks again rob much appriciated bud