Hey guys I'm getting the p1131 error on my 2000 xlt f150 5.4l. I know it's usually a vacuum leak on the pcv hosing, which I did have at the back and replaced as well as other softer joining sections(3 to be exact lol), but I'm still getting this error. Changed out my plugs and cops(as they needed it) and the back two plugs on both bank 1 and 2(plugs 4&8) were both white! Since this is an obvious indication of a lean burning cylinder can I make the assumption my most likely problem is dirty fuel injectors on those cylinders? Yeah yeah I know I'd clean them all lol.

 

Yes, good assumption. I'd replace them all, however check your MAF sensor to be sure the computer is not leaning out the motor. The back two cylinders will always lean out first. Good luck.

 

Yeah maf was dirty but it's been cleaned . I was just going to rebuild and clean them

 

Anyone have any ideas is this right or wrong?

 

Another thought is it's possible there is an intake manifold vacuum leak. Additional air could lead to a lean condition, especially if the leak is near the back of the motor. Check all your vacuum connections and hoses especially the PCV line in that area.

 

When I blow smoke into the pcv hose it looks like it's coming out of the iac valve(the mushroom section on it)? I tracked about 4 other leaks and fixed them but still looking for others as I'm still getting p1131

 

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