Question about 1998 Ford F150 Regular Cab
I would start with the Rubber elbow on the back of the intake, next to the IAC.
This has a habit of cracking, and causing unmetered air after the MAFS to get into the system. The closed loop control is not counting it, and the O2 sensors are reporting the lean condition on the back side.
Ignore the IAC notation in this picture ( only 1 I had ) You are going to want to remove the plastic cover on the throttle body, and take a look at the rubber vac line that is shown in this picture.
The other item could be the intake manifold is loose, but start with the vac lines, clear the code with a scanner, a battery disconnect for 5 min, or 2 driver cycles to see if at least the P0170 & P0174 codes are gone.
The P0136 & P0156 could be a melted wire as mcneb posted about, this is usually by the exhaust manifold. After checking and repairing the vac lines ( if required ) follow the harness from the 2nd set of O2 sensor ( think that is HO2S-12 & -22 if I recall correctly ) to the engine compartment.
Posted on Nov 17, 2009
Testimonial: "That was the problem fixed it and truck runs great! Thank You!"
I had the same problem a few years ago. Codes said lean left and right banks. The enbow was the problem. The code can be reset by disconnecting the battery. Codes came back 50miles later. The crack I had was in the inside joint of th elbow. Had to bend it to see it. Easy fix, but $200 at the dealership because I gave up on it too early.
Posted on Dec 30, 2009
The important codes here are the P136 and P0156 these codes have to do with Ox sensors on the left and right exhaust after the catalytic converters. Look for burnt or broken wires, or wires pulled loose from hitting something in the road.
Posted on Nov 17, 2009
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Posted on Jan 02, 2017
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