EvoM...I need your help with my Evo...I rebuilt my engine back in January (HERE) and have been having problems since then. I am just about to the point where I want to get rid of it.

ANYWAYS. The car has a slight misfire when under light throttle. If I'm on throttle cruising in any gear the car just sputters. And also when I'm off throttle, say coasting down a hill, then get back on the throttle the AFR goes pegged lean for a second or two then comes back to normal. Also 9/10 times I take my foot off the gas it does not go full lean and cut fuel like it should.

I am running on speed density. I have brand new 1450cc FIC, a 450 Walbro, fuel lab FPR and an upgraded fuel rail.

I put the fuel system back to stock except the injectors and still have the same issue. I swapped the MAP sensor and COP out and still have the same problem. tried new spark plugs. Compression is 160 across. My tuner, Tom/TSComp, says its not a tuning issue. We tried to flash different ROMs to see if we could manipulate the problem but nothing changed. We tried changing from air temp sensor to fuel temp and still the issue remains. I tested the injectors all tested the same, the injector resistor is getting 12v and the resistors all tested at 6.1 ohms.

Any thoughts.

 

Have you tried a different ecu??