is it possible that they put in the wrong plugs? I just did the plugs in my 05 gator and there is an updated part number because there was an issue with the old plugs causing misfires. Just went through a crazy ordeal when i used autolites and then started getting misfire code on cylinder4. Tested things over and over. Bought new coils, swapped plug and coil location and still same code came up. went to ford because i thought i had the injector issue. Checked everything and couldn't figure it out. Put in the Motorcraft plugs and it's perfect now. Recheck what they touched before you toss money at replacing sensors and such

 

I have 06 expedition with similar issue, except bank 1 lean p0171, misfire p0305 # 5 opposite bank, surges, bucks, noisy, looses power when you put foot into it. Have changed cmc, because saw it not staying on with scanner, now stays on with foot in it, no change, checked cats, good, compression good, fuel pressure 30 psi at idle, 37-38 when accelerating. I am suspecting cam timing, has all new ford plugs(latest and greatest) and all new coils. hope you find problem. I am suspecting cam timing for lean, and opcm for misfire. If I fix I will send reply. Bubba aka yodaddy

 

Your problem does indeed sound similar. Just yanked out the CMC actuator and it looks OK, but with no circuit diagram it's very hard to test the functionality. Motor functions with DC voltage applied. Looks like it uses torque to determine position limits, since there are no limit switches inside device. Will replace anyway since it's so hard to get to.

Next step is to test with new CMC (I'm guessing no improvement though), then go after the cat for back pressure results. After that, maybe use a degree wheel and check valve timing (could have skipped some teeth I suppose).

Good luck with your 06 Expedition!

 

unless one of the IMRC rods was off i doubt that is your problem, they throw a DTC very fast if in the wrong position.

As you said low FRP will cause lean on both banks but sometimes on bank will throw a DTC before the other which is why cheacking it is a good idea.

I still highly suspect a converter issue. and yes one plugged conver will make your fuel trims almost opposite side to side.

 

I think your right on the plugged converter. We'll put the new CMC actuator and intake manifold back together tomorrow and give it another try.

Converter temps. were pretty even at about 470 F at idle, which is why we went looking at the CMC actuator assembly. Probably drilling a hole and testing is simplest (especially if they are already suspect).

Interestingly, the fuel spray pattern on the aluminum split port intake manifold looked very even.

 

just unbolt the exhaust from the manifolds, its only 2 nuts per side. the 1/2 inch of clearance you will get from that is plenty...even driving it around the block like that you will notice a difference in power if one is plugged I do it all the time. you neighbors may not like it though...

 

Well as expected the new CMC actuator did not save the day (but throttle response now is smoother). Still lean bank 2. On to Cat. test tomorrow.

Thanks Paralyzer for the hint on the exhaust manifold (we need lots of hints)!

Cheers

 

damn, this makes me really want to attempt changing my own plugs.

 

Attempt, attempt??? How could you do worse with one eye closed than some of these Bozo the clown's that you pay good money to? I fully intend to do mine when the time comes. Spent to many years in automotive and have seen enough screw-ups to write a rather large book about. And of course they are NEVER responsible are they?

 

Ok, something weird is going on. Just to be sure the CMC actuator is working we reached back to the actuator rods while one of us floored the throttle. Absolutely no movement. Still sounds strangled too. Yet no error codes (Lean bank 2 eventually pops up).

I'm pretty sure the CMC flaps need to open just above idle, but clearly they are not, even at WOT. Shouldn't the computer throw a code if they are not moving? More and more I am suspicious of the PCM.

 

they will only open when commanded to do so by the PCM, and that will not happen in neutral or park.

 

Paralyzer,

Do you think if we applied the brake and throttle in Drive, the CMC flaps would open?

I have to convince myself that the CMC actuator works before I start on a different path. Especially since the truck worked fine before the plug change. It seems to me the converters wouldn't fail this suddenly (and why would it coincide with a plug change) so I keep thinking we have an electrical issue somewhere, but I'm certainly no expert on Fords (sure learned lots in the past week though!).

Thanks again!

 

i assure you if anything were going on with the cmc it would set a DTC. Nor would a stuck cmc set the missfire DTCs you are getting. you are leading yourself in the wrong direction. you said in your first post your compression is low, stick to looking for the cause of that, which a plugged cat will do, or damaged valve/spring.

Disconnecting the exhaust takes 5 minutes. why havent you tried this yet?

 

Ok I took your advice and stopped obsessing over the CMC valve, and guess what?
Passenger side Cat. is plugged. Thanks for the stern advice!

Someone mentioned that Eastern is a good Cat. replacement brand. Anybody care to comment on cat replacement sources (I'm in Canada).

Thanks again for everyones help here!

 

glad you figured it out