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Hello all just bought a 2007 Titan two weeks ago and am having some issues. This weekend we were on the interstate and the truck started to stutter very violently and lose power. I got it off on the shoulder and after a few minutes I was able to drive it to the next exit where it began to limp along. I let it cool off for ~10mins and we reached our destination that was 5-10 miles away. There was a relay for the ecu in the glove box (left by the previous owner ) which i switched out after reading this forum. We made it halfway home and again violent shaking stuttering backfiring and loss of power. I plugged my scanner in and it gave me a bad camshaft position sensor code and a few others (including the 0420 and 0430) I replaced the sensor and reset the light. The truck ran better but then started its antics again. Now all I have are the two P0420 and P0430 codes but they are showing twice on the scanner. The violent shaking and loss of power only comes after the truck has been driven a while. My muffler guy says its unlikely both went out at the exact same time and I tend to agree. So any thoughts on what I may need to check or do before I replace the cats?
 

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Give me a call and do not put any exhaust manifolds on that truck if you plan on keeping it. The manifolds out there are all junk and will leave you will repair bills x2....
 

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Nightowl are youthe Cajun in question?
He is. Have no fear. Do what he says and boy will you like what you get.
 
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So, it sounds like the standard response when it continually throws P0420 and P0430 is "your manifolds are cracked, you have to buy headers."

Since I'm a human being who can barely afford the $*%&$$#^ payment on the fricking truck anyway, how does one confirm the cracked manifolds? Apparently it happens to everybody with a Titan, based on what I read, but are there ANY exceptions? Cataclean and HiGear seem to do no good. Should I even waste time swapping the sensors themselves? Will putting O2 sensor extension tubes on to shut off the flipping light hurt the cats any more? How can I tell if it's "dumping fuel" and ruining the cats? P0420 and P0430 are the only codes I'm getting, with the exception of a random P0455 that seems to be the gas cap.

NOTE - I am not the OP. I have a "new" 2006 SE that's throwing these codes without any rough running or problems like that.

And, basically, how much does the Cajun fix cost and how much do I have to pay some local yokel to install it?

NOT happy with this development. Beginning to think that the dealer must have been resetting the PCM codes every day to make it look like the SES light wasn't "on". Initially I could get about a 24 hour turnaround on this, but it seems to be getting quicker :( :( :(
 

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Everyone is spot on with most likely the manifolds being your issue, however, you may also have a different or even additional problem causing the codes (especially when age and miles on truck are considered) and one thing that would put me over the edge is to spend a ton of cash and have the problem still, when I'm done.

In general, ....The following additional engine related problems are known to generate the PO420/430 code (which means only that your cats aren't being seen by the computer as operating within their efficiency range:

Intake manifold air leaks
Fuel injector problems (leaks)
Incorrect spark plugs
Ignition timing
EGR problem (not an issue with our engine)
Defective catalytic converter
Oil or antifreeze entering exhaust
O2 sensor(s) not operating correctly
Road damage to converter
Silicone contamination

There are exhaust/intake tests that can be used to isolate the issue at cause: Back-pressure test, Vacuum Test, Temperature test. Also:Check the tailpipe, particularly immediately following start-up, for any smoke indicating too rich AFR (black smoke), water/antifreeze (white Smoke), or oil (blue smoke). Inspect intake system for signs of oil indicating excessive blow-by or cracks that may cause leaks. Look at Long Term Fuel Trims (LTFT). These show the amount (in %) the computer is modifying fuel delivery, based on the 02 sensor feedback. Positive numbers indicate the computer is adding fuel, negative numbers indicate the com*puter is removing fuel. Large positive numbers (>10%) should be investigated further as they indicate the computer is adding more fuel than originally designed.

Statistically, across all vehicles with them, O2 sensors are the cause for failed cats most of the time. The most important thing to remember about Oxygen Sensors is that they were never meant to last the life of the car! They are wear items and need to be replaced as you would brakes, tires or spark plugs. When Oxygen Sensors reach 80,000 miles plus...change them. Catalytic Converters do not go bad by themselves, 95% of the time some other issue with the vehicle will destroy the cat and most of the time it is the Oxygen Sensors. When sensors reach that age they may still be functioning but the signal they send becomes lazy and since they operate in millivolts the slightest signal fluctuation can cause an air/fuel mixture problem and that in turn will take out the cat.

So the questions are: do you have the skills and tools, can you find someone with the skills and tools to do the process of elimination that is the root of diagnostics? Good luck with your solution. There aren't any 'easy' and cheap ways to get to the fix, but they are better than an engine replacement!.
 

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Thanks for taking the time to write that up, Nick. I'm pretty good with "skills" just don't know everything I'm up against, at this point, and a lot of this gets into "too much time" and "requires a lift and welder" to fix. So.... :) We'll see.
 

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JBA Long Tube Headers will bolt right up to the existing b-pipes. No welding needed. The shorty headers do require welding.
 

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But the JBA Long Tube Headers don't have a cat, right? So, I'm confused about how this stays emissions legal and where the cat goes into the system. Sorry, I'm not quite understanding.
 

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It does eliminate the front pair of catalytic converters. Some guys are still passing emissions that way.
 

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Your options for passing emissions depend on where you live and register the truck. Nightowl can help you understand the options which will pass emissions in your locale, and he will answer questions via email pretty quickly. Beyond that, you hit upon the dilemma many of us face - which can we better afford, the time or the money to diagnose the truck? That's a question only you can answer for you. Good luck getting this sorted out.
 

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It's a little unclear as to what "modifications" are allowed in NC. We don't have emissions testing in all counties, just around Charlotte, I think, but the cat and the O2 sensors have to be there, I'm pretty sure.

It probably doesn't matter, as I can't afford the Cajun solution right now, anyway.
 

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If you end up having to replace the cats or manifolds, Cajun will be the cheapest solution if you consider the 2yr time horizon. Cheap replacement manifolds are prone to cracking quickly, meaning you'll be doing this again soon. OEM replacements will make Cajun look cheap - and will crack again, eventually. The system with Cajun keeps one pair of cats and all four O2 sensors, so unless there is CA-type inspections, you'd be alright.
 

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Everyone is spot on with most likely the manifolds being your issue, however, you may also have a different or even additional problem causing the codes (especially when age and miles on truck are considered) and one thing that would put me over the edge is to spend a ton of cash and have the problem still, when I'm done.

In general, ....The following additional engine related problems are known to generate the PO420/430 code (which means only that your cats aren't being seen by the computer as operating within their efficiency range:

Intake manifold air leaks
Fuel injector problems (leaks)
Incorrect spark plugs
Ignition timing
EGR problem (not an issue with our engine)
Defective catalytic converter
Oil or antifreeze entering exhaust
O2 sensor(s) not operating correctly
Road damage to converter
Silicone contamination

There are exhaust/intake tests that can be used to isolate the issue at cause: Back-pressure test, Vacuum Test, Temperature test. Also:Check the tailpipe, particularly immediately following start-up, for any smoke indicating too rich AFR (black smoke), water/antifreeze (white Smoke), or oil (blue smoke). Inspect intake system for signs of oil indicating excessive blow-by or cracks that may cause leaks. Look at Long Term Fuel Trims (LTFT). These show the amount (in %) the computer is modifying fuel delivery, based on the 02 sensor feedback. Positive numbers indicate the computer is adding fuel, negative numbers indicate the com*puter is removing fuel. Large positive numbers (>10%) should be investigated further as they indicate the computer is adding more fuel than originally designed.

Statistically, across all vehicles with them, O2 sensors are the cause for failed cats most of the time. The most important thing to remember about Oxygen Sensors is that they were never meant to last the life of the car! They are wear items and need to be replaced as you would brakes, tires or spark plugs. When Oxygen Sensors reach 80,000 miles plus...change them. Catalytic Converters do not go bad by themselves, 95% of the time some other issue with the vehicle will destroy the cat and most of the time it is the Oxygen Sensors. When sensors reach that age they may still be functioning but the signal they send becomes lazy and since they operate in millivolts the slightest signal fluctuation can cause an air/fuel mixture problem and that in turn will take out the cat.

So the questions are: do you have the skills and tools, can you find someone with the skills and tools to do the process of elimination that is the root of diagnostics? Good luck with your solution. There aren't any 'easy' and cheap ways to get to the fix, but they are better than an engine replacement!.
Where did you copy and paste this from?

The cause of this is rarely ever the A/F sensors, especially on a Titan. 99.9% of the time, it is cracked manifolds.
The cracks allow air to get in, which is read by the A/F sensor....The sensor then tells your ECU to add fuel, which eventually causes the cats to plug up and lose efficiency. If this problem persists long enough, the cats will begin to come apart.
Big deal right? It's just some catalytic converters, no big deal....Guess again Jack, the VK 56 has enough valve overlap to actually pull chunks of catalytic converter into the engine, given their proximity to the exhaust valves.
I won't go into the very obvious details of what happens next, but this problem is pretty serious, and Cajun tuning offers the best solution!
 

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it's not a copy/paste. it's experience. Nissan isn't the only company that uses integral cats on the manifold + a second set. My C4 Corvette that I raced had them and had to stay in tact for my SCCA class. O2 failings also change exhaust temps.....as I stated, the stats are across all vehicles with cats+heated O2 AFR ECU designs. I realize that the manifolds are the problem that all at this forum are dealing with. However, there are symptoms of problems and causes of problems....and the two aren't always as they seem. If your solution choice is to go with a new Cat based design no matter who you buy it from.....using O2 sensors that are more than 80K miles old, will only cause the new Cats to fail sooner, not later....and for exactly the same reason. Dirty fouled O2 sensors slowness causes them to tell the ECU to dump fuel. That's a wash, rinse and repeat solution....not a real complete solution.

My answer to the OP is a long version of "don't do a half-assed job"
 

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I'm not going to argue that the sensors can get lazy or just go bad all together, because they can and will.
I will argue the 80,000 mile thing though, considering my 98 Monte Carlo went 225,000 miles with the original o2 sensor and converter.
Saturn had their cats positioned about a foot from the exhaust ports, and my brother in law's SL2's o2 sensor and converter are both working well at close to 200k.
If your engine is running well there is really nothing that can cause them to fail, aside from poor maintenance and/or abuse.

FWIW, I'm putting 2 new AFR sensors in my new headers today, only because I'm already there :wink:
 
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