2005 Ford Ranger 3.0 Rough Idle with Codes P0300, P0301, P0302, P0316, and P0174

Actually, after re-reading the data, what you have are bank 1 and bank 2 long and short term fuel trim readings. Not sure on what you need. Thanks.

The next thing to do is check the long term and short term fuel trims at 2500 and 3500 rpm. This way we can confirm if we are indeed dealing with a vacuum leak. If bank 2 does indeed have a vacuum leak that 15% should drop to within limits at higher rpm. A good cheap little scanner is the Foxwell NT201. Around 80 dollars here in Canada where I live.

I will go get them now but it will be a bit as the truck is at a different location at the moment. Thanks again for the assist.

Got the numbers for 2500 rpm.  Can't get 3500 as the truck's govenor kicks in around 2800ish and truck rpm's surge.

Two files.  One with the engine right after start up.  No CEL.  Second once truck is warmed up and CEL is on and flashing.

Of note is that towards the end of the warmed up data the truck did the "click" thing and started running normally.  It's not an audible click, just the way I describe it.  It's like a switch is thrown and the truck immediately starts running fine.  CEL stays on because codes are stored but it stops flashing and if I clear it while the truck is running fine then re-do the scan, FIXD says "No issues detected" and CEL stays off.

If after it "clicks" I come to a stop for anything more than a few seconds the CEL will start flashing again and then the engine will begin to misfire, sometimes a little and sometimes enough to shake the truck.   If I accelerate with it misfiring it will sometimes take off (no often) but usually it just shakes and goes about 5-10 mph until it "clicks" and then it takes off.    

p.s.  I bought a truck yesterday so I will be unavailable from early morning until late tomorrow evening (truck is in NC and I'm in VA).   

The click could be a valve hanging up? You could try some marvel mystery oil in the motor, maybe it will clean the valve guide

Thanks for the reply. I misused the word click. There is no sound or noise at all. It's like a switch somewhere was flipped and the truck just runs normally.

Heads were replaced about 30k ago so no valve train issues.

Pretty sure it's narrowed down to vacuum leak or fuel delivery but can't seem to find anything wrong with either.

The outlier might be a sensor that is confusing the ECM but???

What about the alternator? Is voltage dropping too much before it responds?

Your description of everything - I still think you are dealing with a vacuum leak.At idle, spray propane around the intake and all vacuum hoses and listen for rpm changes.Monitor stft for both banks- it will go negative if you find the leak. Why I say vacuum leak your LTFT on bank 2 drops to below 10 and your truck starts to run fine.Also on your first graph you were at positive 15 on bank 2 at idle. Thanks for the good description.

Sorry for the break in communications. Kidney surgery - don't recommend it.

Smoke machine showed small leak around IAC bolts. RTV didn't seal it so bought the gasket that should come with the new IAC's but didn't.

Smoke machine tonight showed no leaks around IAC but a good amount of smoke coming from under the driver's side of the engine, below the exhaust manifold and somewhere near the starter wire.

I can't seem to see where it's coming from specifically and not sure what vacuum line would be running that far down the block.

As always, any ideas would be appreciated. I can't seem to find a pictorial view of vacuum lines in that area.

smoke on driver side and truck misfires at idle and bank 2 lean at idle, which is driver side. sucking in extra air before upstream O2 sensor but- how is it sealing itself once you reach certain speed??

Loose or bad gasket, small pin hole in # 2 bank exhaust manifold? Sounds crazy but air getting in there before upstream sensor would throw trims off at idle.

If nothing obvious around bank 2 exhaust manifold and that upstream sensor -I would try spraying soapy water around entire manifold and sensor. Truck running at idle of course. Thanks.

Hey Robert- did you ever find the problem with this? Just curious. Thanks.