[tchudy]

I've been fighting a lean fuel issue this year and I am looking for some advice. I have a 1986 944T. Lindsey dual port wastegate, MBC, 3BAR FPR, Stock DME, Stock injectors, Wideband Air/Fuel Meter (2 years old). Fuel pump is original. Engine was completely rebuilt about 3,500 miles ago. All vacuum lines new. Everything on the engine is new or rebuilt.

Last winter I replaced the fuel rail with a used stock one and put new seals and screens in my injectors (injectors had been cleaned and flow tested after the engine rebuild). I cleaned inside the fuel rail as well as I could. I have a fuel pressure gauge under the hood that confirms that I have the correct pressure in the rail at idle and while reving the engine. I tried swapping out the DME but no change. The only other thing I did last winter was to add a Lindsey catch can off of the AOS.

At idle my A/F ratio is between 13.5 & 15. During normal acceleration (no WOT or boost) my A/F ration is about the same as idle. When I go to WOT and at about 3,000RPM boost starts kicking in. A few seconds after boost my A/F ratio drops to the bottom of the gauge, lean at 11 or below. If I let up and come off of boost the ratio is again, same as idle. At boost when the A/F drops there is no loss of power. I tried lowering the boost but no change. Spark plugs all look good. I did a compression and leak down test...all good.

I ordered a new fuel pump to rule out low flow. Not sure what else I should be looking at. I am assuming that my wideband O2 meter is not faulty since it is so new. Any help would be appreciated.