Tanker Yanker
New member
Please keep us posted....I will be shocked if senors clear it up. Fingers crossed for you!
When V8 Cats go bad?
- Thread starter TeryT
- Start date
TeryT
New member
Thanks!
Jeffy
New member
I was thinking of the downstream cats, my bad. You can still cut the cat off the manifold and weld on a universal. Or go with the Doug Thorley shorty headers and weld a universal cat onto that.
WhiteBoomer04
New member
So I'd assume you'd have to remove the manifolds to do this? Can't see how they would get in between the pipe and the engine, to weld the back portion..:help:
Jeffy
New member
Correct. If you don't have rust it's not too bad taking them out. My car came from the rust belt though so I paid someone else to do it
I didn't read this whole thread but wanted to share an experience I had with a friend's '08 V8. She threw the usual 420/430 code and we determined, after some troubleshooting, that her cats were the culprit. Cats don't just go "bad". The precious metal inside the honeycomb can get coated and their efficiency simply diminishes. We had plans for removing the manifolds and inspecting her cats. If they needed to be cleaned with muriatic acid, we were prepared to do so.
Backstory:
Her vehicle had crud inside the fuel tank, which got sucked up and clogged the fuel pump inlet. This in turn starved the engine intermittently and caused misfires, back fires, stalls, etc. While I was troubleshooting this misfire, I let the fuel starvation blow out the honeycomb inside the passenger cat.
When the pass side header was removed, we discovered the blown honeycomb material and cleaning wasn't going to do anything productive. The driver side looked good. So, she opted to order both manifolds from Amazon, Dorman brand, and we installed them. We even went to the thrift stores to buy a deep pot for soaking the cats and everything! I'm ready for the time when I have to clean my cats, I guess.
Simply monkeying with the O2 sensors isn't always the answer because you're shooting the messenger, so to speak. The O2 spacers shouldn't be needed if everything was working top notch until now. Even new O2 sensors aren't needed unless crappy fuel was run through the system for years and the heater tip got clogged. O2 sensors are simply doing their job and reporting what they're finding.
I'd drop the manifolds and inspect the cats. If they look intact, I'd stab at cleaning them by following various YouTube vids. This is also the time to do some welding around the flanges where the famous tick tick sound originates on the pass side. After cleaning, re-install them and see what happens. This is a LOT of work, I agree, but the cost is less than $10 for materials. If you can't weld, take it to a buddy and show them the YouTube video where the tick tick noise comes from and throw down a bead or two.
Anyway, just my .02 cents worth.
Backstory:
Her vehicle had crud inside the fuel tank, which got sucked up and clogged the fuel pump inlet. This in turn starved the engine intermittently and caused misfires, back fires, stalls, etc. While I was troubleshooting this misfire, I let the fuel starvation blow out the honeycomb inside the passenger cat.
When the pass side header was removed, we discovered the blown honeycomb material and cleaning wasn't going to do anything productive. The driver side looked good. So, she opted to order both manifolds from Amazon, Dorman brand, and we installed them. We even went to the thrift stores to buy a deep pot for soaking the cats and everything! I'm ready for the time when I have to clean my cats, I guess.
Simply monkeying with the O2 sensors isn't always the answer because you're shooting the messenger, so to speak. The O2 spacers shouldn't be needed if everything was working top notch until now. Even new O2 sensors aren't needed unless crappy fuel was run through the system for years and the heater tip got clogged. O2 sensors are simply doing their job and reporting what they're finding.
I'd drop the manifolds and inspect the cats. If they look intact, I'd stab at cleaning them by following various YouTube vids. This is also the time to do some welding around the flanges where the famous tick tick sound originates on the pass side. After cleaning, re-install them and see what happens. This is a LOT of work, I agree, but the cost is less than $10 for materials. If you can't weld, take it to a buddy and show them the YouTube video where the tick tick noise comes from and throw down a bead or two.
Anyway, just my .02 cents worth.
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Jeffy
New member
All good info, I only have one thing I'd do differently. The v8 manifolds are known to crack and cause exhaust leaks. It doesn't happen to everyone but it's very common with both aftermarket and OEM manifolds. For the same price as OEM manifolds, you can get Doug Thorley headers and weld on some universal cats, which is much better quality and also gives you a performance boost. Or of your state doesn't require emissions inspections, get the long tube headers for even more performance. Just saying.
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WhiteBoomer04
New member
Good information. So to clarify, you replaced the manifolds and soaked the cats, and that worked? I have watched a lot of videos of cat cleaning and I dont think Ive seen one where there was a successful outcome. From what you have seen what chemicals/processes is most reliable for cleaning efficiently to remove the 0420/30 code?
TeryT
New member
Yeah, that just sounds like a bunch more "fun" than I care to have right now!
So I've had the new O2 sensors in for a few days, but have only driven the 4R perhaps 10 - 15 miles. Today I will be driving it further, and based upon my experience earlier with the CEL coming back on about 20-30 miles after being cleared, I should know today if it was the sensors.
If the CEL comes back on then I will just have someone change the cats for $650 and be done with it . . . after almost 190k, these things are to be expected.
Tanker Yanker
New member
Damn, guess you're gonna need to pm me an address to send that $5 I had riding on cat failure lmao!
That's a negatory. One of her cat honeycomb matrix was blown so we opted to not clean a faulty cat.
TeryT
New member
Well we shall see . . . it didn't come on yesterday after about 45 miles and 3 stops. When I tried to clear it twice before (B4 the new sensors), the CEL came on with much fewer miles. So I am hopeful.
TeryT
New member
So this will be my last post regarding this - unless the Xmas tree CEL lights come on again. I'm thankful to report that I've driven it more than 100 miles over several days, and replacing the O2 sensors seems to have done it!
So God willing, this little story is concluded (as far as I'm concerned).
So God willing, this little story is concluded (as far as I'm concerned).
TeryT
New member
Lights back on - sorta
So now there is another little thing to note in this episode after all. The lights came back on after maybe two weeks. I had the codes checked and it was 4 or 5 misc. codes that made no sense. I had them reset the codes.
A couple days later the lights came back on and it had one 420 code, which I had them reset again. A few hundred miles later, on a trip to NM, the lights were back on. But get this - they go out again after a short time all by their self!
I've come to the conclusion that my 4R's computer is a little crazy, and have put a small piece of electrical tape to cover the two annoying lights on the right-side instrument cluster (I can live with seeing just the one CEL on the left-side).
Any thoughts?
So now there is another little thing to note in this episode after all. The lights came back on after maybe two weeks. I had the codes checked and it was 4 or 5 misc. codes that made no sense. I had them reset the codes.
A couple days later the lights came back on and it had one 420 code, which I had them reset again. A few hundred miles later, on a trip to NM, the lights were back on. But get this - they go out again after a short time all by their self!
I've come to the conclusion that my 4R's computer is a little crazy, and have put a small piece of electrical tape to cover the two annoying lights on the right-side instrument cluster (I can live with seeing just the one CEL on the left-side).
Any thoughts?
bassmacka
Member
I recently installed the spark plug defouler on the o2 sensors after the cat. This has seemed to solve the issue and you can get it on amazon. worth a try.
TeryT
New member
Thanks. Yes, I've been considering that option. Does it affect the )2 sensor's ability to regulate?
After replacing the sensors, the V8 has a little more per and the computer shows better mileage. Would installing the defouler thingies impact that?
(BTW - the lights stay off most of the time now, but occasionally pop back on for a short time. They came on yesterday for the first time in maybe a couple weeks. I was driving a little longer distance than I normally do. I'm wondering if it is due to the cats heating up for a longer period of time that is now causing the lights coming on. But again, the CELs go out now usually within a day or so.)
bassmacka
Member
Try Adding the spark plug defouler to the o2 sensor after the cat. It solved the problem for me.
