195000 miles on engine,,02 sensors read lean #1 and 2....i have r/r mass air flow sensor,cleaned it properly,,same with EGR valve.replaced fuel filter,,
no apparent vacume leaks..replaced tp sensor ...engine runs good..additive cleaner and higher grade gas than walmart 87 octane..not much time passed light returns....engine mpg is falling from 20 to about 13..i plan to install valve stem seals in fall (light puff of blue smoke on start up) most ford owners know the cause......uses a little more oil between 5000 mile oil changes..
used map gas and carb cleaner around intake manifold...no noticeable change in engine idle,,,of course changed air filter.....my next thoughts are air injection system at the firewall tucked in behind the plenum not regulating the airflow in the system correctly causing the lean code on my scanner????????does any one have this experience with that valve..good truck since it was new..not ready for china scrap yard yet!! HELP!!!! am i over looking supply canister that supplies clean air to that valve??????email please! thx in advance for your input!

 

What's your timing with the spout disconnected....and also no other codes? if it's throwing a lean code I'd suspect it to be the ECT sensor....

 

have you replaced the O2 sensors?

 

at first the #2 sensor was scanned as faulty,,i replaced it,,,soon after both sensors appeared as faulty #1 and #2 bank..square one and out $50 bucks

 

no other codes..Ect sensor????

 

Just because it says lean doesn't mean it's faulty, maybe the engine really is running lean.

 

ect=engine coolant temp. at this point the engine running lean is obvious. as to the why...have you done the plugs, wires, cap, rotor, and coil lately? maybe something in the distributor is bad causing bad timing. good luck man

 

Wasn't there a TSB on the O2 sensor harness? Make sure none of the wires are getting shorted out for the O2's.