2004 expedition 4.6 EB 2wd p0301 and p0420car

[04ebexpy]

my expedition is pulling both of these codes I have already been told on the forum the 420 code is likely the cat. I’m just wondering if the cat can affect my fuel mileage or if I have unrealistic expectations. I am showing about 13.6 mpg via the dash for a mix of highway and city.

Also, I recently pulled a 301 code I could feel a small miss at idle then first thing in the morning when it is cooler out if I have to accelerate fairly quickly the check engine light starts flashing typically it still accelerates fine I think.

This expedition was given to me for free though in terrible condition it has 209k and I did all the coils new and new Motorcraft plugs when I got it because my wife's family had driven it for God knows how long with a passenger bank misfire.

While idling the other day I pulled the injector plug for cylinder one and it became a dead miss. Same with when I pulled the coil plug. So I am assuming they are good. First thing in the morning the idle is slightly variable other than that and the motor seems to be leaking fluid from everywhere possible it seems fine.

what I am hoping for is figuring out how to get better gas mileage on my 50-mile round trip commute. And obviously, find out if I have to drop the money for a cat. Once I look into the leaks I may be back to discuss those as well. I can't exactly afford a newer car so let's see what happens



Side question in your opinion if you had to guess how much longer would a 4.6 that was horribly maintained beat on and towed with last?

 

[Hamfisted]

A bad coil (coil spring, coil, boot....) may act fine under no load at idle. They're cheap, I'd throw a new one on there just to be sure. A misfire neglected for a long time will in fact damage the cat on that side. If you are getting the P0420 code then chances are the cat is trashed. A pair of Walker cats is about $600 on Rock Auto. Make sure the PCV valve is clean, it might slow some of those leaks.

https://www.rockauto.com/en/catalog...5,exhaust+&+emission,catalytic+converter,5808


-Mike

 

[04ebexpy]

Thanks, I may have an extra coil laying around I may try or I may just switch coils and see if the misfire follows.

Yea the cats aren't cheap. My question is will it cause long term harm not to replace it as well is it what's causing my low gas mileage.

 

[1955moose]

Anytime exaust is not allowed to fully escape an engine is not a good thing. Pressure builds up inside, which may explain your many oil leaks. A flashing check engine light while accelerating is most likely an electrical issue, more closely the secondary ignition. Coil, spark plug wire, spark plug. You might also want to do a compression test of #1 and #2 cylinders. The reason I said #2, is sometimes a head gasket or cracked head along with a burnt/bent valve can throw you off on diagnostic. As to your question, how long will the old girl run? That's a tough one. I've seen motors that should have died, go on for more than five years. If you chose not to fix it, I'd strongly suggest keeping your oil level up, as well as your coolant. Your fix I'm thinking is pretty minor compared to the many we see here on the forum. It might be worth putting a few bucks into. Hell, you got it for free!

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[TobyU]

"If you has a flashing light you had a bad solid miss. Replace the plug on 1 of that is th eonly one you had a code or pending code for.
I would be looking at result reading for cylinder misfire counts.

Get the misfire count repeated scans showing nothing on any cyls and that means it's not missing.

You an damage a cat from a miss if you keep driving but usually the cats emission reduction ability gets reduced but the car still runs fine and no MPG change at all.

If a cat gets restricted or plugged, that's a different story.
You can somtimes tell a lot by holding hand over exhaust tip to block off.

Muffler shop guys are usually good at knowing what feels right.
I don't think I have never put a cat on any vehicle. Might have had muffler shop weld a universal 59.99 on one back in late 80s or early 90s but I don't think so.
I have had several cars with them deleted.

Never had a clogged one. Had a full size chevy van blow the plug out of one so I put a freezze plug in it. Lasted for years and I sold it that way.

 

[04ebexpy]

Thanks for the help guys I appreciate it ill have to tackle this. When I have more time and money.

So I assume my 13 mpg is standard then?

What is the cheapest route to get a cat?

And what are the most common oil leaks on the 4.6?

 

[1955moose]

I'd do cart wheels if I got 13. Cheapest cat if you need one, is finding a guy parting out a Expedition/F150, and grabbing that one, and bolt it up yourself. Short of that theirs cheap ones from muffler shops, but usually don't have a long life. Go with a mid price one if you go a shop route. And oil leaks, that can be anything. First edition expys have head gasket leaks, but that is not an easy fix. If you steam clean or degrease motor, be sure and cover all coils on top of motor, along with the intake.

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[04ebexpy]

Thanks for the reply I appreciate it seems I have unrealistic hopes for mileage.

 

[1955moose]

Actually, except for the oil leaks, sounds like it's not that bad. These are strong motors. You've got one of the last 1st Gen small blocks. With regular oil/trans service, it's not uncommon to go 300,000 miles. We used to run these engines to 350,000 before we yanked them out of our Taxis here in San Francisco.

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[04ebexpy]

I meant gas mileage though I appreciate the taxi info as well.