06 4.6 3v Explorer -*P0420* *corrected* and possible exhaust leak

96eb96

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#1
Make
Ford
Model
Explorer
Year
2006
Miles
101,000
Engine
4.6L 3V v8
Looking to buy this and working with a dealer. Except for this it runs perfect.

I believe there is a new(er) cat - it has those California Carb numbers on the shield (along with a bunch of other new parts, 02 sensors, maybe the last owner gave up). No idea how old it is.
The explorer has a pending cat code and I scanned it. Pre and post 02 sensors match in waveform, so that MAY implicate the cat (or exhaust leak). The other bank looks bad to, the waveform is moving somewhat. Fuel trims unremarkable (under 5).

Even with this code, it passed a state inspection. (only one monitor not complete and a pending code).

These trucks are notorious for exhaust leaks, but we don't really hear any. If it is it would be a pinhole. The manifolds look old and the shields fell off, so it is suspect. Possibly when you floor it there could be one, small, but it is debateable. Sounds great on cold startup.

The dealer said every 5.4 truck he sells needs that repair, but he is not sure with the 4.6.

What is your opinion? Could an exhaust leak cause this? One tech there thinks it is the cat. He also said some aftermarket cats die in weeks. I think it could be a leak.
I also see some replaced coils, maybe someone drove it with misfires?
 

grcauto

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#2
More than likely it needs a new cat.
 

nickb2

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#3
As a supposedly pro tech that ppl say I am, I am 100% in agreement with this comment
The dealer said every 5.4 truck he sells needs that repair, but he is not sure with the 4.6.
The 4.6l is NOT notorious for exhaust manifolds. If you would be asking if you should buy a ford with a 5.4, three valve, I would just say stay away.

Yet, you state this was a parts thrown at truck.

If it was driven with misfires, good probability it cooked the cats, dumping raw fuel will kill a cat in no time, as most know here, but there are way to know.

First, I would try to find a guy with a smoke machine. Or do as others do here, use a shop vac!:cool::D

Now, here is me just going over the top, there is a fuel pump module on these trucks. So first step, is to look at fuel trims with under load. What are they saying as of now? 5 up or down? Cuz if it is a +5 constant, ecu is trying to correct. Not unremarkable. Sure the ideal is 0, but if it is humming with a +5 trim constant, and never reaching 0 at some point in time, maybe someone was just to lazy to swap out all the plugs. ETC. Not a lot of techs like working on these trucks, they short cut. Most are scared of stripping the threads. I see these trucks with plugs over 160k km's oem. :eek:

You could also do a propane enrichment test, that is readily available to the back yard warrior.

I am really curious as to how you get wave forms, what type of scanner are you using.
 

nickb2

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#4
But you are looking at an egr code, excessive flow, so focus on that. If you have a proper bi directional, you can check that function.

Soaking the egr in some seafoam or carb cleaner over night and giving it some attention the next morning would be easy enough to do. I think these are vac driven, and ford algorithm even in 2006 was quite precise. It is not uncommon for these valves to stick open from carbon buildup.
 

nickb2

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#5
I was told to not play the ethanol boogyman here, but is it a flex? I am sure if you shove a camera up there in the egr, you will see a whole bunch of gunk preventing the egr to seat properly hence causing an excessive flow code. Is there a "K" in the 8th digit of VIN?
 

nickb2

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#6
If your not sure, a proper scan tool will show that in live PID data. Look for fuel pump module info, look at ecu correcting for flex fuel.

Anyway, I am trying not to go into weeds here, but focusing on bad cats wont make a egr code go away. Fords are to smart for that, you would have gotten p0420 or something to that effect.
 

nickb2

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#7
If you only have a mickey mouse code reader, I can suggest real cheap solutions for that. I have been very active in this dept, most who come here are not interested unless they have a use for the tech beyond watching brittany spears on you tube.

 

96eb96

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P0420 - Stupid me for putting in an EGR CODE

This 3v does not have EGR, it is a baby 5.4 with the cam phasers. Dealer told me he hates selling 5.4s because they are either trashed or close to it and he gets nasty comebacks and bad reviews. His mustang has the exact engine and trans like the explorer and said it is an excellent powertrain, of course if you maintain it. Not as good as the 2v in reliability but very close. He said there is an easy 100k left in the explorer. The 4.0...he said you will not find on my lot. I know the issues there.

1. I have a decent code reader. I use forscan, almost dealer level, it gives the 02 waveforms and they certainly follow each other. I tried it on my other fords and the downstream sensor is flatlined.
2. Dealer changed the plugs, even he remarked there are a bunch of cheap coils and some OEMs and that spells death for the cat if not done on time. His mustang had the same thing when he got it, with a bad cat. He suggested 8 new ford or denso coils (he will give me the parts at cost). He said at 100k the plug could have had slight misses and you know where that is going.

Dealer wants to put a cat on it, I did suggest smoke test...we will see next week...
 
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96eb96

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#9
Explorerforum and the internet has tons of cases with that engine needing exhaust manifolds. But usually it sounds like a motorcycle at startup, this don't. The manifolds look very ratty. It may be just starting.
 

96eb96

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Everything checked out otherwise - the manifolds really look bad, have very tiny leaks and are getting replaced with ford parts. Dealer said they will take care of it with a good deal on parts. New cats too.They said that is one job you don't want to diy without a shop. Then he showed me some tech suffering with a 5.4 :lol:. He said a 3-5K oci and there will never be problems with that engine. For some reason it don't have the 5.4 phaser issue, even though they are very similar.
 

nickb2

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#12
To be honest, I was stupid also, that is what the third valve is for " to replace the EGR", or so I was taught, hence should have caught that sooner. You made an honest typo, I went with this code, the 422, and didn't even bother to open my database.:mad: So I am real sorry for that. I have been at this so long, I just assumed without checking, this is what happens when you get to comfortable. ;)

Great on the forscan, great software when you know how to use it. We should get along fine.
 
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