It could well be, although eliminating the 'usual' causes is the only way to be sure...... or swap to a stock ecu !nimhbk said:have a tomei ecu in mine set for 100 ron juice and 1.2 bar could this be the reason its running rich at 0.98 bar
In simple terms just the MAF though it does twiddle fueling based on many other factors that aren't relevant on WOT. However, AFR is also determined by what air get to the cylinder so any leaks will mean the MAF reading is wrong. Dodgy injectors or fuel regulators could also mean more fuel than expected gets squirted in. If you've not earthed the MAF yet it is an excellent start.steve963 said:what inputs does the std ECU get to determine what fueling?