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Cat Converter? and Engine sounds like a diesel

4K views 10 replies 5 participants last post by  CyclePath 
#1 ·
Whats up everyone my problem isnt so drastic that I cant drive but I have noticed a decrease in fuel economy....getting around 290 a tank with stock sized AT's and feel that the truck isnt as powerful as it once was almost seems like the engine is choking / has poor flow. The SES light popped on and gave me 0420 and 0430 initially and about a week later gave me 423 EVAP (small leak). Truck seems to accelerate well but slowly. I probably need to replace those cats but whats got me a little concerned now is once my engine warms up it makes a ticking sound that when at idle is similar to a diesel lacking that deeper growl.

The ticking sounds like its coming from the front of the engine, almost like a pulley bearing is going but with the codes im not certain and wanted to ask the club for their opinion.

Its a 03 Xterra SE with 98K. I gave it a full tune at 90K (oil change, diff fluid change, tranny fluid change, new NKG plugs, fuel filter, air filter and re-timed the engine) it also put in a new AC compressor and distributor at around 88K.




Any ideas what that ticking is? If i need to replace the cats which ones do you all recommend and if you've swapped them yourself; got any tips for the install?

Cheers from Annapolis!
 
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#2 ·
Possible causes for the 420/430 codes are:

 Three way catalyst (Manifold)
 Exhaust tube
 Intake air leaks
 Fuel injectors
 Fuel injector leaks
 Spark plug
 Improper ignition timing

The "ticking" / dieseling you are hearing could be caused by a timing issue. Check your timing and ignition again before replacing the cats. Maybe the distributor moved on you.
 
#3 ·
Thanks, it's definitely not a timing issue rechecked it and its good. All bolts are tight and rotor is well rotating : ). Any suggestions on which cats work best with the xterra.

I dont want to drop those Benjamins only to be even more frustrated.
 
#5 ·
In my experience a ticking sound can either come from an exhaust leak, or low oil pressure/low oil.

To test for an exhaust leak, start the car and put a towel over the exhaust pipe. If your problem is an exhaust leak, the ticking will get louder. Then you can start searching for the leak.

If the ticking does not get louder, I'd suggest simply doing an oil change. Make sure to put in a full 3.5 quarts, and I'd suggest to put in a quart of Lucas Heavy Duty Oil Stabilizer as well. So 2.5 quarts of oil, 1 quart of Lucas. The Lucas helps raise oil pressure. Hope this helps!
 
#6 ·
Dennis that's solid reasoning right there!

Legit I wanted to try that but didnt have enough rags to plug it up. Ill try that again as for oil I thought it was all good but I might as well take another look.....do you think that the issue of oil pressure would cause ticking only when the engine warms up? Id figure the oil would expand far more than the block.
 
#8 ·
Thank you all for the advice, I'm beginning to think it's an exhaust manifold leak. Found this guy on youtube showing his F150 with an ex manifold leak and the sound is very similar to mine.....

https://www.youtube.com/watch?v=ZyPDZ8QHSBU

Im just concerned with the lack of power it certainly feels like its a little backed up. Would a ex leak cause that though? Ugh I wish I didn't go back to work tomorrow! While I bought this truck with the intention of doing all the work on it, I gotta say with the amount I drive I get to have many automotive learning opportunities with this silver beast!

Ill figure it out in the next week or so I'll be sure to keep you posted
 
#9 ·
Cracked manifold also sounds about right to me too.

BTW - You only need ONE rag to block the exhaust pipe, as you press it over it with your hand to block it, and the rag is just so it doesn't BURN you. Plan B, ask your buddy to block it while you go up front and listen, etc.

:D
 
#10 ·
Well the EVAP code is gone, I guess it must have been a loose fuel tank cap or something simple. But the 420 / 430 codes are still there. I did the seafoam trick in the crankcase, tank and brake booster vacuum line and the only place I saw smoke was through the exhaust so that's good.....I really dont want to replace the manifold but I'm happy to know what to look for at least.

The ticking is still there but I think that's unrelated unless the exhaust back pressure is so high it's affecting the engine. Its funny I have a stethoscope with me all the time as I'm a nurse and decided to use it to try to isolate the tick (must have look like a complete idiot with that trick) but using it definitely helped me isolate it to the black case on the passenger side of the engine (by injectors ?) but what ever.

I just ordered a Exhaust back pressure kit and will test the cats with it soon. If I need to replace them I'm feeling motivated to make a write up or at least take pic's throughout the process to document later how to swap those cats if one does not exist currently.
 
#11 ·
As for the cats....does it make sense to delete the secondary ones? I dont think there are any o2 sensors on em and have seen folks on here get rid of them. Will that make emissions testing more challenging? Any "gains to be had" from this? Thanks
 
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