Sigh...P0307/P0420 codes...what I've done...suggestions?

[Sterling Archer]

Ok, my ride has 238,6xx miles on her. Had started missing/hesitating at most all rpms (rough idle, but not in danger of stalling with constant little surges at cruise). Last week I had new plugs installed (Motorcraft), the shop also replaced two COPS on the right bank, front two cylinders.

Ran fine for 2 days then developed a misfire and codes as above. Took it to autozone to scan (My scanner is packed away somewhere...) And the kid said ALL but one cylinder was misfiring (Don't recall which one.).

I order a cheap set of COPs on Amazon and replace all BUT the 2 my mechanic replaced. Ran better but still misfire in #7. Removed COP to replace with an extra I had not used and saw I forgot to put dialectric grease the one I had put on. Put a gob in the boot of new COP #2 as well as the harness connector (for all of them). Ran MUCH better. Thought I had it licked. Multiple COPS on cylinder, same problem...

Today it starts up again..MUCH more noticable. Got coded for P0307 AGAIN.

No visable coolant leaks or smells, no vacume leak sounds/hisses, oil changed 2 months ago looked fine. Research says bad cam/crank sensor would keep engine from running at all. I see NO arking/spark leakage at boots.

ALSO, possibly unrelated but notable...on a cold start, it sounds like I have an exhaust leak on right bank BUT after 30 seconds or so....it goes away. Been going on for some time but even before the misfire, did not seem to affect drive quality. Doubting cracked header as it would sound awful all the time and not heat up in 30 sec to expand and seal itself.

Doubting vacume leak or low compression due to on-again/off-again nature of problem.

I am leaning towards a bad injector(s). With 238k+ the internal screens may be plugged or pintles sticking. Ran a heavy dose of gumout FI cleaner for a full tankfull (done over 4 days). New pump was put in tank 2 years ago (at about 170k), inline filter is still original but will be changed this weekend just for ***** and giggles.

I can get remanufactured set of 8 bosch injectors from ebay for $100. Worth the chance? Is there a special tool to remove/install? Best way to relieve fuel pressure?

Comments? Thanks!

 

[Quasar]

To be sure it is still not that COP, switch two cops around and see if the code moves to the plug number you switched it too.

Ive never messed with injectors before so i cant say for sure either way on that part.

P0420 in my past experiences usually equalled a bad cat convertor although i cant remember which side. P0420 is one side and p0430 is other if im remembering right.


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[Sterling Archer]

To be sure it is still not that COP, switch two cops around and see if the code moves to the plug number you switched it too.

Ive never messed with injectors before so i cant say for sure either way on that part.

P0420 in my past experiences usually equalled a bad cat convertor although i cant remember which side. P0420 is one side and p0430 is other if im remembering right.


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I'll try it again for ***** and giggles but It has had the oem and 2 new replacements in that cylinder this last week and still has the same issue.

 

[Quasar]

Are the oxygen sensors original also? Usually something else has to be off to cause a cat converter to fail. It very well could be an injector thats bad and maybe o2 sensors being weak causing the cat to fail.

I think the same principle should work for the injectors. If you swap two of them and it is causing the misfire, the code should move to whatever cylinder the bad injector is on.

Just didnt want to send you on a wild goose chase if my advice isnt 100% perfect.


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[Sterling Archer]

Update.

I moved injectors and coils around yesterday with still a miss in number 7.

Did an oil change today and it looked good. While doing that I happened to look down while pouring in the oil and noticed I did not see any belt....I looked further down in and see it heaped at the bottom. It finally let go at 238,7xx miles...literally as I pulled in the driveway. Went and got a new belt and got that in. In changing it, Itook off the intake tube from the intake and airbox and noticed the bottom edge of the rubber lip was bent inward whenever it was last removed and installed (It could have been me or my shop, I can't remember the last time I had it off). That would certainly mess up the mass air reading so I fixed that on re-install. Doing that I smelled gas and looked around the fuel rail on bank 2 and saw what I thought to be gas. On starting, there was a fine spray coming from between the rail and the injector...I buggered an o-ring.

Got a baggy of four new fel-pro ones and replaced it, no leak. all together and running but still has slight miss. I will have to see if it throws a code again (I disconnect the battery when working around engine out of habit from having cars with electric fans.) Driving it about 5 miles in town has not given me a code(s) but tomorrow I will be driving about 35 miles for work.

 

[thenaaks]

Have you checked the spark plug in the offending cylinder? I've seen chunks of carbon get lodged in the electrode and cause a misfire. Saw it most recently in my own weedeater. Running fine one second, then just died. Quick and easy to check.

 

[Sterling Archer]

Have you checked the spark plug in the offending cylinder? I've seen chunks of carbon get lodged in the electrode and cause a misfire. Saw it most recently in my own weedeater. Running fine one second, then just died. Quick and easy to check.

Possible. Wll give it a look later today.

 

[Liam Burke]

I am having the exact same trouble.... Same cylinder, the same combination of codes, same symptoms, and same attempts to fix. Do you remember what the fix was?

 

[stamp11127]

Don't wait too long for him to answer, he was last on the site back in 2015.

 

[Liam Burke]

Well... maybe.... hopefully.... someone else has had the same issue that can answer... I'm At a full on loss short of replacing the cats, and I can't even afford the parts for that.