2002 Lincoln mountaineer missfire and low power

2004LB7

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Ahh, the smog test. That sucks.
You can try the bore scope from the upper O2 holes looking down at top side of the cat's honeycomb. I have done it on a Hyundai once but was not happy with the picture quality of the small hand held snap on scope I have.
You might need to drive it more to get a code to pop up. If the misfires refer to one​ side of the engine than It could be plugged on that side. If you could see the 02 sensors reading and if one was reading different and was on same side as misfire than that would help confirm that it was one of the upper cat's and which one. The lower cat is after they come together and would be more of multiple misfire.
Dirty air filter, cracked bellows on intake tube, intake gasket, throttle body leak, plugged pvc valve, other things to look for.
I would just drop the pipes try to visually inspect/shake maybe even try blowing compressed air both ways see if any material comes out. Then when all else fails, I cut them open from the top side with die grinder pull the material all out then weld them back up like it never happened and use the 02 spacers, if it solves the issue get a new set and weld them back in
I have a boroscope so it wouldn't be too difficult to remove an O2 sensor and take a look. I'll put the scanner back on it and watch the O2 sensor readings also and see what we get
 

Chevy1925

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Honestly, you should be throwing a code for cat performance if they are plugged.

Like I said, wouldn’t concern myself with it till you finish the other fixes. Plugs and injectors can make a big difference in performance
 

TheBac

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Honestly, you should be throwing a code for cat performance if they are plugged.

Like I said, wouldn’t concern myself with it till you finish the other fixes. Plugs and injectors can make a big difference in performance
Not necessarily. But....all this is guesswork until a scanner and fp gauge is put on the vehicle and actual data is posted. Id start with fp and o2 sensors, then move on to the cats if the misfire codes continue to pop up. Ive been thru a scenario very much like this with my kid's Grand Prix. Fp tested out ok, so did o2 sensors. Ended up being the cat.
 

2004LB7

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Thanks, that's what I thought

We did pick up the pressure gauge but need to come up with an adapter that will fit this port. This is just one from another family member and doesn't have all the parts. Maybe we will rent one from an auto parts store if it comes to it.

Brother ordered new lash adjusters and is looking at injectors next.

Took it for a drive around town and it didn't throw any codes, missfire or otherwise. That's good so far.

One thing we noticed is the drive train / steering seems a little too tight. It feels like it is in 4WD on the pavement. You can feel the tires, front and rear, squeal or squirm a little when making turns. I know this thing is full time AWD but this seems a little too aggressive to me. Then again I don't drive any fords so I'm not sure is this is normal for their AWD systems. I do remember being told a while back from a previous owner that the transfer case for the AWD system was replaced. I think under warranty. Don't know what the issue was
 

Chevy1925

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Not necessarily. But....all this is guesswork until a scanner and fp gauge is put on the vehicle and actual data is posted. Id start with fp and o2 sensors, then move on to the cats if the misfire codes continue to pop up. Ive been thru a scenario very much like this with my kid's Grand Prix. Fp tested out ok, so did o2 sensors. Ended up being the cat.


Fords of that year were real good about it. Each one that came in stored the code regardless if the check engine light was on or not (the MIL would go on and off as I was told by the officers). If it was straight plugged, MIL was on
 

2004LB7

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Did a fuel pressure test. Looks good. At idle and light engine load it stays at 64 psi. Under full throttle it only drops to 60 psi.

Borrowed the scanner again so we can watch the O2 sensor readings. What numbers/range would be good or when would we suspect something may be wrong?

You think its worthwhile to disconnect the exhaust from the manifold and take it for a spin and see if it has any more power? If so then suspect the cats are plugged? Or will the O2 sensors give us enough data?

Otherwise if all seems ok then we are just going to drive it and assume it is just that gutless. It seems like it is fine for light city driving but if you wanted to pass someone or merge in fast moving traffic you better have plenty of room.
 

2004LB7

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Disconnected the exhaust from the manifolds and took it for a test drive. No noticable difference in power. I forget to stick my boroscope inside to check when I had it apart. Oh well. I can always pull the O2 sensors and take a look.

Did an oil change and took it for another drive and watched the O2 sensor readings.

Most of the time they hang around 0.8 to 0.865 with a few fluctuations above and below. Except for bank 1 sensor 1 which often times hangs around 0.145 or so and only briefly goes up to the what the others are at. I'm thinking it would be a good idea to replace both sensor 1 on each bank
 

Chevy1925

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Won’t hurt but make sure you are in closed loop while watching. If you happen to be giving enough throttle to be in open loop or enough rpm, readings will do that
 

2004LB7

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Yeah, we ran out of time and daylight to take a run on the highway for close loop testing. Only reason I think it would be a good idea to replace them is the large difference between the two upstream sensors. And the pending code (running too lean) for that side. If nothing else it wouldn't hurt.
 

2004LB7

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They are on order.

I guess while we wait for the injectors to get here we can swap the O2 sensors and see if it follows.
 

2004LB7

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Just a little update

Vehicle is running great. No codes have returned. Just took it for a trip up to the mountains, 70 miles one way and didn't have any issues other then the locked up viscous coupler that we knew about before.

Got that replaced today and the AWD works like a champ. No more binding during turns

Almost done. Just a few cosmetic stuff and some seat wiring to do
 

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2004LB7

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Still waiting on the new injectors. Forgot to actually order them. Found out when they weren't in the box of parts. Ended up just reusing the same ones for now.

I did change out all the lifters / lash adjusters and no change in ticking noise but it does seem to have a smidge more power. Even my brother seems to think it is stronger. Otherwise it is still weak compared to my Duramax :D. For our driving it does seem to have just enough HP to not be an issue
 

2004LB7

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Well the CEL cam on. P0430 - cat efficiency low bank 2

I think I will swap the bank 1 & 2 down stream O2 sensors to see if it follows. If not then it is likely that the cat is bad.

On the viscus coupler, it fixed the steering bind and drivability issues. So smooth now
 

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