Ford p1518 and p1151?

Hey everyone, a check engine light on my 2001 mustang came on (P1518) which is a trouble code for the intake manifold runner control. I watched several youtube videos about this and they recommend replacing the bushings that control the arms that open and close the intake. However when I check both sides of the engine, I am seeing that both the arms and the bushings are both intact. What could be causing this problem then? I also have another code p1151 which means there is an incorrect air to fuel ratio detected by bank 2 o2 sensor.

My symptoms are: The car will rough idle sometimes and have a slight misfire with rpms going up and down like the car is going to stall and other times will idle completely smoothly. I am also getting poor gas mileage and slight loss of overall power.

I changed the spark plugs and tested for vacuum leaks, but didn’t find any. Any thoughts?

Thought ? Yes , put down the tools and step away from the vehicle . As many threads you have about this Mustang at least have a shop diagnose it and then you will not be just guessing at what to do.

A quick internet search of the P1518 Ford code lists these as the possible causes…

  • Faulty Intake Manifold Runner Control (IMRC) actuator
  • Intake Manifold Runner Control (IMRC) harness is open or shorted
  • Intake Manifold Runner Control (IMRC) circuit poor electrical connection
  • Faulty Powertrain Control Module (PCM)

Notice bushings are not listed…

As for the P1151 code… same source. Notice vacuum leaks are pretty low down on the list.

  • Faulty Upstream Oxygen Sensor Bank 2
  • Fuel pressure high or low
  • MAF sensor dirty/defective
  • Vacuum leak on engine
  • Leaking fuel injector or fuel pressure regulator
  • Faulty Powertrain Control Module (PCM)

Sooo Check the IMRC wiring and connectors that may have been damaged when the new engien was installed. If you have the IMRC actuator off the old engine, swap it over and see if the problem goes away.

Next tackle the P1151. Hook a scan tool to the car and watch the O2 sensor for bank 2 and the MAF sensor and see what they do. Maybe swap in a new O2 sensor if it wasn’t replaced with the new engine. Clean the MAF. Check the fuel pressure. Check the regulator by pulling off the vacuum line to it and see if it squirts fuel…it should not!