94 302 running lean
 

I have a 1994 Mustang GT that has a TFS Street intake 70mm TB, Pulleys, K&N FIPK,Bassani X-pipe and Flowmasters.

I just installed a Lunati cam, TFS twisted wedge heads, 1.6 roller rockers, 24lbs injectors, 190lph fuel pump and 75mm MAF calibrated to 24lbs. My car is running very lean. My mechanic says he thinks the O2 sensors aren't working properly. Could he be right or could I need a custom tuned chip? Someone else said that I might need a fuel pressure regulator. What could it be?

You don't need a fuel pressure regulator. You should have plenty of fuel with your injectors and fuel pump. How do you know you're running lean and how old are those o2 sensors? Considering the money and time you just spent, I would replace them if they are original.

------------------
351W 89 Mustang GT Convertible

Hello jimberg,

Thanks for your reply. I brought my car to a different mechanic for a second opinion who said it was running lean. I guess he could hear it and smell it. In addition, when I'm driving it on the freeway, even at around 70mph, it feels like it's spuddering a little. The O2 sensors are original with about 94000 miles on them. I'm gonna have them replaced on Monday. Thanks for your help. T.Capitule

Get your cars CPU hooked up to a scantool before you buy anything. Find out what your injector pulse width is and find out you O2 sensor readings. This will tell you for sure whether or not you need new O2 sensors. It might me a faulty pump or incorrecly installed pump.

Which brand of pump did you buy? The Ford Racing pump is complete but the BBK is only partial. You have to use parts from your old pump leaving room for error. Sensors are expensive, find a scantool first and check your MAF readings as well. I damaged my sensor when installing the Vortec unit and it made me lean out. I had to buy a new one. Goodluck.

------------------
95GT B303 cam, 1.7 rockers, 65mm TB, milled heads, 355's K&N, BBK Longtubes, Flowmaster cat back, pulleys, msd coil, 9mm wires, Tremec 3550, Pro5.0 shifter,10.5 Motorsport clutch, FMS aluminum driveshaft, weld in subframe connectors