1997 lean condition

[Killer Ride]

It's not a grand but not cheap found a local guy $ 650 installed all 4. It used to be more in 2011 for replacements had to be OEM 6-700$ each. Would have been $3,500. universals today cost $70-80 ea. Thank God they changed the rules.

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[Killer Ride]

These are the original cats also depends how much mileage, and how its driven. This truck only has 166,000mi my F150 had 267,000 when I had to replace them. Luckily back then in 2011 I got some used ones for $50 each.

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[TobyU]

I think the difference is when one is plugged vs when you are checking to see if one is working. A working one is hotter after do to the process taking place inside. If mostly clogged nothing gets through and the reaction taking place can't exit to show it increase in heat.

 

[1955moose]

Here in the Bay area, decent quality cats are about $400.00 to $500.00 each. You can buy the cheap ones that last about 2-3 years for $200.00 to $300.00. Actually a catalytic converter will last the life of vehicle, avg 250-300k. But this only happens when fuel entering is clean and lean. They just go bonkers when raw unburned fuel enters them on a regular basis. You'd think after all these years 1975- present, they'd make one that held up better. But why, when they can sell you a new one. It's like getting caught in an Hov lane by yourself, it ain't cheap.


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[crowncrazy87]

Ok. Well pulled some live data this evening and here is what I got...

SHRTFT1- 1.6% (would go from -4ish to 8l
LONGTFT1- 3.1% (this would vary some but no more than a few numbers)

SHRTFT2- 10.2% (varied widely both positive & negative.
LONGTFT2- 24.4% (varied widely )

SHRTFTB1S1- 3.1%
SHRTFTB1S2- N/A

SHRTFTB2S1- 15.1
SHRTFTB2S2- 99.2

 

[crowncrazy87]

Live data info. No misfire codes just the lean codes for both banks.

 

[1955moose]

Your #2 is your problem. Check those cats, probably gone. So no smoke coming from intake anywhere? And also replace those 2, 02 sensors with Ford or Motorcraft ones. You found your problem. Now the fix. You obviously had/have a bad misfire that caused this.

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[crowncrazy87]

Well I bought the rig on Monday from a lady who said it just lost power while driving and it wouldn't hardly go 10mph. I originally found 2 fouled plugs fixed that. That's probably what got to the cats. I'll look into checking the cats on that side and see what I come up with.

 

[1955moose]

Best way is the screw in back pressure gauge. Why did those 2 plugs foul? Be sure those 2 injectors aren't leaking, and that both those coils are sound and sparking. Your problem sounds like a plugged cat. Were the 2 fouled plugs right next to each other, if so do a compression test of those 2. A leaky head gasket can cause a drop of 2 side by side cylinders.

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[crowncrazy87]

Opposite banks on the fouled plugs. Not sure the exact cause of it but or how long it had been that way. Once I replaced plugs and wires misfire code has not shown back up. Just the lean codes.

 

[Surfnski]

I just went through this on a 5.4. Same symptoms anyway... Did a smoke test and found a minor vacuum leak at the intake manifold. Replaced the manifold and gaskets and all is good now.

 

[Killer Ride]

The clogged cats can cause the fouled plugs,extreme exhaust pressure and heat from having nowhere to go can cause predetonation and other issues including blown heads and bent springs

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[Killer Ride]

An exhaust guy does not screw a gauge in he drills a tiny hole then affixes a pressure gauge to that tiny hole. Has you start the car and gas it a few times and voila. Once he's done he just zaps the tiny holes with the welder. Takes about 5min they usually don't charge for the test

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[1955moose]

I've heard of that way too. Most guys here in the Bay area unscrew the 02 and take a reading that way. Yeah those exaust benders do love their torch.

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[TobyU]

I've heard of that way too. Most guys here in the Bay area unscrew the 02 and take a reading that way. Yeah those exaust benders do love their torch.

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Yes, and he spot where he welds will be the first to rust out on the pipe.

 

[1955moose]

Most muffler guys I've run into are hacks. Their are some good ones don't get me wrong. But an acetylene torch, and a half inch drive air impact is pretty much their tools. It's a win win though for the shop. They get paid for 95 percent of their work. They rarely get away from their comfort zone, mufflers and pipes. But beyond having them diagnose and replace a bad catalytic converter, you don't want them chasing anything real techy. And that's ok. You wouldn't ask your shoe cobbler to make you a custom pair of Italian Boots, in most cases it's not in his wheelhouse.

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[crowncrazy87]

Ok. So before I break loose the exhaust from the manifolds (rusty as all get out) I took my IR thermometer and did temp tests per what I found online so I let the engine run till it reached operating temp (roughly 10 to 15 minutes)... I didn't write down the numbers but here is what I observed.

On bank 2:
front cat had a temp on the back(outlet) weld seam of about 100° hotter than the front (inlet) weld seam.

Rear cat back weld seam was roughly 100° cooler than front weld seam.

On bank 1:
Front cat had almost the same temp on both weld seams.

Rear cat was about 100° cooler on the rear weld seam.

Looks like my next step in diagnosis is to get that's rusted up bolts loose and drop the exhaust from the manifolds!

I do appreciate you guys helping me out with this!

 

[Killer Ride]

You bet. Just paying it forward! Had a couple of Ol' guys help me out in the past with these trucks and motors. Now it's your turn when somebody has this type of problem.

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[VoxVeritatis]

Lean condition most frequently points to vacuum leak. In addition to vacuum hoses, the entire edge of the plastic intake manifold is suspect. My '02 developed a manifold leak at front of engine above crossover, but underneath where it could not be visually inspected. Couldn't locate it until it became bad enough to manifest itself. Replaced manifold and completely resolved the issue.

 

[crowncrazy87]

The 1997 4.6L has the aluminum 2 piece intake. I have tried everything to check the gaskets short of tearing it apart. If it was leaking bad enough to cause the severe drivability issues I'm having. The water test and spraying of carb cleaner would have found it!

That being said not saying that a leak somewhere is not contributing to the issue. I'll know more once I get the exhaust dropped and see what happens!