5.0 supercharged 2012 xfr. Timing job was recently done and after that it’s been lean bank 1 code(only bank 1 not bank 2). Smoke tested it can’t find any leaks. What can I do next. Some symptoms rough idle, fluttering/bubbling noise from exhaust sometimes when i let of the gas(different from usual backfire at higher Revs), sometimes when I start the car doesn’t matter cold or warm the revs will climb steadily to 2500 stay there for about two seconds and come down to normal.

 

MKXFR5.0, based on my past experience with the 5.0L motor, I had the water pump replaced because I had a major leak in the coolant system and they pulled the intake off of the car. After that, my car ran like hell (granted, had a rich condition on 2 cylinders). Traced out all the problems and it ended up being that 2 of my injectors appeared to have "failed" (not sure if they failed or got stuff inside of them). I am wondering if you may be suffering from something similar. I know the car has 2 high pressure fuel pumps, I forget if they are tied together or if each one feeds a side of the engine. I mention this as if they do feed separate sides of the engine, you may have a high pressure fuel pump that is starting to go and it is driving the fuel rail pressures all over the place, leading to a lean condition as the one side is being starved of fuel.

 

Good point by Thermo!
Yes each bank of the engine is supplied by a separate gear driven pump. Now what can bite you is the fuel pressure sensor on the 5.0L engine is ONLY on the passenger side of the engine. So if the gear pump for the drivers side has a problem no codes will be set and there is no way to measure the drivers side fuel pressure in real time either. Not sure why it was designed this way?

Can you please post the actual codes? It does make a difference. Any chance it could be the PCV diaphragm leaking?
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I already replaced the valve cover and gasket on the passenger side(bank1) it came with new pcv valances on it. What other symptoms can I look for to see if it is a fuel pump problem.

 

The pumps should have codes for any problems but can you measure the fuel pressure with your scanner? I forgot which one your using?
Might help?

Not sure what a PCV valance is?
Here is the diaphragm and I have found the after market has improved these too?
In case anyone is interested they claim to have used a better material "military grade Fluorocarbon" whatever that might mean!





Here is the auction.
PCV Diaphragms

Not to expensive at $25 each. 5.0L V-8 uses two and 3.0L V-6 has one. Both use the same part.
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sorry I meant pcv valve. I did have something on my scanner does this mean anything.

 

Sorry not sure what the scanner is saying? Value 1.260?
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