02 Ranger with 3.0 Flex motor, 375K+ miles. Been chasing an issue for a while now, but am about at the end of my diagnosing capabilities.
Issue started with a misfire on 5 and rough running engine with no codes showing up. Now the motor is getting worse.

Idle a little rough and no power when accelerating hard. The engine sounds like a popcorn popper under hard acceleration. Motor revs up to 4K but does not pull or shift gears until I let off the gas.

The code that initially showed up indicated a bad Camshaft Position Sensor. Changed that and the Sync assembly - as per instrucions, exactly positioned same as old one. New codes showed up - P1152, P0175, P0171. Cleaned the MAF, rail fuel pressure OK, can't find any vacuum leaks, replaced both upstream ox sensors, and changed #5 ,6 injectors.

Motor still runs the same - like crap, like a corn popper on acceleration, smooths out if only slightly accelerating, but stumbles n bumps on steady cruise speed over/around 60 mph - and no codes showing at present.

I really, really don't want, nor can I afford, to take it to the dealership, but I may be forced to if I can't figure this out sometime quite soon. I make my living with this truck so, no truck, no work till this issue is solved.

 

Went for another buzz around the neighborhood. Codes showed up. Same codes as before - P0171, P0175, P1152. AFTER both new ox sensors and cam sensor. Popcorn sound seems to be gone, but still stumbles n bucks a bit on cruise over 50, and not much power. Skips a bit on idle, but no misfire code showing up. I have to be heavy on the gas and much higher than I like on the RPM's thru the gears to keep from getting run over in traffic. I need suggestions.........

 

So much for any help from you guys

 

Well sounds like you've been busy on this one. I'm not clear about how you came to determine cyl 5 was misfiring, if you had no CEL lit or blinking & no codes set????

The other codes are a bit confusing, as they seem to conflict with each other, unless you really do have two seperate problems, or maybe wrote down a wrong code number.

P0171 = Lean bank-1
P0175 = Rich bank-2.
P1152 = lack of bank-2 O2 sensor switching, indicating rich.

So if the bank one P0171 code is correct, here is a link with a list of things to check for.
P0171 - Check Engine Light Diagnostic Trouble Code Description

Some thoughts for consideration. Keep us posted on your trouble shoot.

 

Since bank-2 has been running rich, how do the plugs look for carbon fouling????

Bank-2 running rich suggests the computer is having to add fuel because of too much air, maybe from an unmetered vacuum leak, or maybe an acting out/leaking/uncontrolable fuel injector has the bank-2 O2 sensor switching stuck Rich!!!! So doing a read on All cyl bank-2 spark plugs, might offer up a clue as to whats going on with bank-2.

Have you done a compression test yet, or hooked up a vacuum gauge to see what clues it suggests????

Did the problem come about suddenly, after some event, or slowly over time????

With the mileage on this puppy & not knowing its maintenance/repair history, or where you are on all due past & present scheduled maintanance replacement items, (other than the O2 sensor replacements & MAF sensor cleaning), it could be a number of things, so we need more clues to make better guesses on which way to proceed on your trouble shoot.

Has the PCV valve ever been replaced????

 

nope, but checked for "rattle". 90% of the miles are highway miles.

 

There are certain issues that can be determined by looking at the condition of the spark plugs - I think this is partly what pawpaw is probing for...

The plugs are new - have they been checked since they were installed? How do they look compared to the plugs on the other bank?

Since the condition started to progressively show up after changing the camshaft position sensor and synchronizer, I think, if it were me, I would have a look at that - you mentioned that you "Changed that and the Sync assembly - as per instrucions, exactly positioned same as old one." - could it be possible you were sold a defective part or one that isn't quite working the way it should? How did the wiring and connectors look?

 

Good that you've done a compression test & say its ok, might be helpful if you'd post the numbers.
Good that you've kept the scheduled maintenance up & checked the PCV valve & that it's loose, not gummed up & sticking, BUT the PCV valve shake/rattle test isn't good enough, as if this puppy has never been changed in 375+K miles, its already lived nearly 3 life times, so there is no way to gauge how much internal wear has taken place, how well its seating/sealing, nor how weak its spring has become. SO, seeing as how its a calibrated for/unmetered vacuum leak, best to keep it replaced on time & thats usually around every 100K miles!!!! Carefully check its rubber fittings & hose for loose fit, dryrot cracks, ect.

I know you said the plugs were replaced, so how did the old ones from cyl bank-2 look for carbon fouling, or how do the new plugs look????

The computer is unhappy with fuel trim on both banks, one bank is lean, the other rich. O2 sensors give the computer feedback on the O2 level in the exhaust & the computer uses that info, along with other sensor inputs, to vary the fuel injectors squirt time, so that the air/fuel ratio in both cyl banks is kept as close to 14.7/1 as possible. So if we have unmetered air leaks, leaking fuel injectors, dirty, or clogged up fuel injector filters yielding a lean squirt, or corrupt feedback from the O2 sensors, fuel trim & the fuel trim tables stored in KAM get corrupted, so have you disconnected the battery B- cable, to wipe the KAM???? Then have you done the cold & warm idle relearn proceedure, so the computer can relearn its cold & warm idle strategy & begin to rebuild new fuel trim tables with the cleaned MAF sensor & new O2 sensors input????

Since we only have 2 O2 sensors, one for each bank of cylinders, we are seeing the average of all cylinders in a bank, so if one cyl is acting out, it'll corrupt the O2 sensor PID back to the computer for the entire cyl bank. Now if we had an O2 sensor for each cyl, it would be easier to know how each cyl is doing, but we don't have that luxury, so we have to revert to a spark plug read, to get an idea whats going on with a particular cyl air/fuel ratio.

Seeing as how you say compression is ok I assume you don't have any oil fouled plugs.....right?????

On the low power issue seeming to be associated with the replacement of the cam sensor & sync, I agree with Furyus1, have another look at that part & its alignment. Have a look at timing with an induction timing light at various rpm.