Nissan Titan Forum banner

1 - 4 of 4 Posts

·
Registered
Joined
·
63 Posts
Discussion Starter · #1 ·
So I have an ever present P0420 code which from all I can search on this site is pretty common. Problem is no ones seems to some back with what fixed it. Most threads relate to installation of headers. Anyhow here is what I have done so far:
1. Repaired exhaust leak at the clamped Y-pipe (welded it)

2. Ran vacuum test. Pulled 21hg of vacuum. Quick throttle snap lowered it to 5hg but it jumped right back to 21. 2500 rpms it held 21hg steady. So no exhaust restriction at all

3. New plugs. OE NGK platnium

4. ECU relay replaced

5. Tested 02 sensor on bench and got .96V with the torch test. Both left and right side rear sensors tested the same.

6. temp on cats was about 20-30 degrees hotter on rear of cat than on front

With that information what would you suggest I do next. I don't wan't to start replacing cats unless I know there bad. How else can I test them? Any others tests you recommend?


One other question: How many times must the engine get a bad code before the light goes on? I reset the ECU after all the tests and drove it for 100 miles shutting it off and restarting several times and the light never went on. But I pulled the codes with the ignition switch and it showed a P0420 with no light.
 

·
Registered
Joined
·
63 Posts
Discussion Starter · #3 ·
I'm guessing that the cat may be poisoned and not plugged based on the vacuum test. Can an emmisions test tell me this? We don't have emmisions in my county but the next county over does so I could go get it tested if that would tell me anything.
 

·
Registered
Joined
·
63 Posts
Discussion Starter · #4 ·
Another question: Will a reflash of the ecm do anything? Any idea of costs? I am about at the point of gutting the front cats and using defoulers.
 
1 - 4 of 4 Posts
Top