Hi new to the forum, and was needing help diagnosing a problem.

I have a 2000 f150 with a 5.4 past few months it has been throwing a p1151 code meaning it is coming up lean on the driver side. I just changed the plugs and it didn't help, neither did changing the fuel and air filters. cant find any vacuum or exhaust leaks. Replaced a bad injector along with the spark plugs and its still coming up lean.
The truck also seems to bog down at about 50-60 mph if i let off the gas and coast it will drop about 300 rpms.

It has me confused and annoyed, i have true duals with glasspacks could that be causing it?

Any advice is greatly appreciated.

 

Lets look at the code and what you did.
A lean condition on one bank can't be caused by a fuel filter that is common to all cylinders.
A plug or coil won't cause a lean condition without reporting as a cylinder out with a code to support it..
Air filter is ahead of the Mass Air meter and throttle body so has no effect on one just one bank.
Lean is excess air that has not been metered by the Mass Air meter.
Since it's indicating one bank; from the point of the intake 'runners' for each cylinder on that bank, an air leak from a bad intake gasket or some reason air is entering would be detected by that bank's Ox sensor.
Also an air leak large enough between the exhaust manifold and the sensor could also be detected by the sensor and result in the code.
How/why is the code set?
The program sets the code when the fuel tables shift out of limits to the rich side trying to adjust for the excess air.
So, you likely have an air leak at some point being detected by the OX sensor.
Besides the OX sensor controlling average fueling, it does trouble detection and reporting by causing the setting of the code.
Good luck.

 

1151 is also possible faulty o2 sensor . Graph o2 sensors both banks , upstream and downstream . Tap in with a scope or a multimeter , and confirm reading of offending o2 sensor to rule out wiring or PCM issue . Compare up and downstream to rule out sensor . A lean condition will affect both .

 

For that code, I'd first suspect a lazy O2 sensor.

 

Excellent post Bluegrass - I rep'd ya'. I saw a post for a 4.6 that had a single bank lean condition and it was related to the EGR valve. can't remember if it was a leaking vacuum line or something with the valve itself allowing air in.

Hopefully someone with more knowledge on the 5.4 can say if it would be possible for this to be a cause. If my Expy was here I'd just go look for you, but it's miles away right now...

On edit: don't know what I was thinking... It was the PCV valve that fixed a Left Bank problem on a 4.6 -- I apologize....