New to me '05, need guru advice

cknpro

Test Drive
Location
Southeast
Just purchased an '05 Off-road with 167K. Runs smooth and tight. I noticed it had a little more exhaust sound out the pipe than I expected, but didn't give it much thought. Well, it threw a P020-030 code after about 30 miles - cats both banks. I took it to my local exhaust guys, they knew what the codes were before I told them, then when they heard it as I pulled onto the lift they knew what was going on. Seems the cats, all four, have been blown out, hollow, nothing in them. I live in a state with no inspection and it has lived it's whole life here so....apparently at some point they were stopped up, so somebody "unstopped them." They basically told me if the extra exhaust sound doesn't bother me, then there is nothing I have to do. I'm contributing a little more pollution than normal, otherwise no power loss, no other problems. They put a couple "extensions" on the sensors and that cleared the codes for about 50 miles then they came back on. Otherwise this truck is looking pretty straight for the miles and money. The problem is I bought this for my daughter and I don't want her to have an issue that caused a legitimate CEL for something serious and not know it because this "non-issue" has it on all the time.

Is there secret way to short circuit those exhaust sensors or otherwise fool them into thinking things are normal? The guys at the shop said they thought they had heard of something that may now be outlawed - like a plug that the sensor sits in so it sends "normal" signal.

I'd rather not sink the money it looks like would be needed to put the exhaust back to OEM or working AM replacement.
Any help out there?

Thanks - Dennis
 

Jbat

First Fill-Up (of many)
Location
Utah
I believe you can put a resistor inline with the o2 sensor so it sends the proper signal to the computer but you will have to do a little research to determine the proper resistor for yours. This will show the o2 sensor as normal and will make it not throw codes so that if the CEL comes on for something serious she can get it looked at.
 

cknpro

Test Drive
Location
Southeast
How would I go about finding that information - just google oxygen sensor resistors?

ETA: I did the above and good grief...the answers and options are crazy. From "this works" to "this will blow your engine up", from "these $3 rectifiers" to "these two adjuster boxes for $300".
 
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Muadeeb

Nissan al Gaib
Admin
Location
Dallas
Just a resistor won't work, because the ecu is expecting a changing signal over time, something a single resistor won't do unless you put it inline with the sensor and it sounds like you may not have the knowledge to do that.

I'm thinking the CEL eliminators they put in weren't long enough so there's still too much exhaust gas getting to the sensor. Several users here run setups that aren't too dissimilar, so the concept of what your mechanic did is sound. You can either go back to the mechanic and have them extend the rear sensors a bit more, or drill out a couple of spark plug non-foulers and put those inline.

This is assuming your code is a p0420 & p0430. If it is, then know it took 50 miles to come back because it takes the ecu that long to verify the sensors are good after clearing codes.
sent via wild ferrets
 

cknpro

Test Drive
Location
Southeast
That is indeed the codes, verified three times now. Sounds like you're spot on. That's what the exhaust mechanic said - it may come back on in 50 miles. The ones he put on were about 1.5" long.
I also noticed while sitting in the driveway and revving the engine up you get a little puff of white smoke when you let off, but only when you get the rpm's up there above 4K. The exhaust guy said that was also further evidence the cats are non-existent as that was a sign of excess hydrocarbons.

I can install a resistor if I knew which one and where to put it. The information out there is all over the board though. But I don't mind cutting and spicing...

I did see online where some folks were using longer tubes with 90's in them, but it was on a sketchy site IMO so...but it may be the key. I thought about taking these back off and welding them up a little to restrict the flow to the sensor. I already paid for them and what could it hurt? I don't think they are stainless.

I am capable of some serious mechanic work....just maybe not always willing. ;-)
 
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