Greetings.
Replaced my MAF sensor and the upstream O2 sensor on bank 2.
Greatly improved, but now getting
P0174
P0300
P0306
P0316
Have tried checking for vacuum leaks and haven't found any....running out of ideas and $ to try things.
Any suggestions?
Thanks

 

Assuming 3.0l V6

You should include definitions since you already looked them up, I assume, lol
P0174 System too Lean (Bank 2)
P0300 Random/Multiple Cylinder Misfire Detected
P0306 Cylinder 6 Misfire Detected
P0316 Engine Misfire at Startup

Bank 2 is drivers side of a Ford V6 or V8

Lean means too much Oxygen coming from this bank as seen by the O2 sensor which can only see/detect oxygen

And you have Misfires, and a specific #6 misfire which is on Bank 2
What happens when a cylinder misfires?

Well one thing for sure, no Oxygen is burned/used up because there was no combustion, so that Oxygen is dumped into the exhaust manifold and the O2 sees that as extra oxygen, so "lean" code

So I think you should focus on the Misfires because I think that is setting the lean code, not the other way around.

What has gotten "better"?

What does the spark plug tip look like in #6?
Does it show oil, rich/lean condition?
Steam cleaned?

Inspect the Coil pack, look for cracks
You don't mention the year, but I know the 3.0ls in the early 2000's did have some bad coil packs installed at the factory, they would crack after 100k miles or so

2004 to 2006 3.0l Rangers had a TSB about bad valve seats causing misfire codes

 

Sorry about not including the definitions... Had posted previously, thought on same thread..Sorry about that as well.
Ok, I'll pull the plug, which is less than a month old and which I correctly gapped prior to install. Wires coil and plugs all replaced at basically same time, working the last three weeks.

 

What year is the Ranger?

And what does "working the last three weeks", mean?

 

Working three weeks means **** poor editing.
New Plugs, wires and coil within the last three weeks
2003 3.0 non flex manual transmission
258700 miles, approx

 

O2s were do, usual life for an O2 is 100-150k miles, they run out of chemicals, so should be on 3rd set of O2s

So engine ran poorly 4 weeks ago and then you added the new parts and it ran fine for 3 weeks but then started to run poorly again and turned on the CEL(check engine light) with these codes

See what #6 plug looks like

You might dump a can of Seafoam or similar injector cleaner in the gas tank if you haven't in the last year, once a year is all thats needed


But with a 2003 3.0l engine it may come down to doing a compression test because of the P03xx codes you have

TSB seen here: https://therangerstation.com/ford_ra..._05-26-3.shtml

There is no exact line for 2003 and 2004
So best to eliminate this as the problem or find out it is the problem and stop wasting time and money on non-fixes

 

Thanks for the info...
Can pull plug, maybe even do the compression testing, after that I'm in severely over my head
Will have to see what happens w the above
Thanks for your time and trouble

 

To do proper compression test, pull out ALL spark plugs first
Cold engine
Install compression gauge in #1
Push gas pedal down to the floor, this turns OFF fuel injectors, also allows maximum air into the engine
Crank engine until you hear at least 5 "hits" of compression, you will hear it don't worry

Write results down
Move to next cylinder

2003 3.0l runs 9.3:1 compression ratio so expected would be 165-175psi, but this really depends on the compression gauge so its not about a high number, it more about how all 6 cylinders compare to an average you get from the test