jetmec

Hi every one I'm new here, I recently bought a 2009 4.olt V6 Mustang convertible, the computer tells me it's running lean, so my question is where's the mixture screw on it? Thanks guys

JimC

There is no mixture screw. No carburetor to adjust on the car, everything is computer controlled.

What are the codes you are getting? That will tell you where to start looking for the problem that is causing your lean condition.

jetmec

Hi Thanks for the reply. my OBEC connector tells me its lean bank on both sides, So if its all computer controlled how do I adjust the mixture

Derf00

You don't. It's all computer controlled. If you have a lean code that means you most likely have an intake leak somewhere after the MAF sensor and before the intake valves. Find the leak, fix the problem, problem solved.
Could be a hole in the intake tube, a bad vacuum line, a leaky throttle body gasket or intake manifold gasket or cracked intake manifold.

Less likely but still plausible is a leak in the exhaust before the Cats. You would hear that though as it would sound like a machine gun that speeds up and slows down as you rev the motor.

jetmec

Hi Thanks for the post, I will look in to this,