Hi all,

I have been trying to fault find error code P0420 Catalyst System Efficiency Below Threshold (Bank 1) engine light comes on randomly could be a day or a week.

Infiniti G37 2009 done 97,000km but is an import so this could be incorrect.

what I have done.
Swapped Bank 1 & 2 O2 sensor 2 over
Swapped Air flow sensors over
removed Bank 1 cat soaked over night in dish washing liquid, blew out with air compressor and washed out with the water hose (garden hose)
ran injector cleaner for at least 5 tanks
removed injectors and bench cleaned, not flow tested but all looked to flow the same pattern
swapped spark plugs side to side, plugs didn't show anything looked
Checked Fuel Pressure 52psi

cleared the code, let engine warm up, held rpm at about 3000rpm and done a diagnostics and this is the results. when I backed off throttle car hesitated

see attached.
Video uploaded

Thanks in advance for any help.

 

All the dish soap would do is remove a light soot coating. I suspect you may have metal contamination on the catalyst. Or, the substrate is disintegrating.

Can't speak to the hesitation but I bet you need to replace the catalytic converter.

 

my concern is what if something has caused the cat to fail or die faster its only a 2009 done under 100,000km cat shouldn't fail within that time.

I have just uploaded another lot of results running at idle.

Has anyone removed the cats altogether, if so how do you deal with the sensors. in New Zealand we don't have emission laws.

 

You'll have to search the forum to verify but you can get "test pipes" that replace the converter and have a bung off the side to fit the secondary O2 sensors.

 

Further testing,
if I hold about 3000rpm the Fuel trims Bank 1 & 2 go to about -20 so running rich, as soon as I de throttle this is when the car misses.

checked Fuel Pressure 52psi

any ideas what could cause rich under load?

 

Generally, when an engine runs richer with more RPM (when parked) it indicates a dirty MAF or restricted cat.

If you haven't already, clean both MAFs.
Also, if you can adapt a 0-30 psi gauge to a O2 sensor fitting, you can measure the exhaust pressure pre and post cat.

Data log and graph the post cat O2 (sensor 2) on both banks. You want to see how often and the duration of the switch from lean to rich and rich to lean.

Data log both MAFs (either g/s or voltage) when revving the engine and see if the air flow is different between them. If a cat is restricted, the MAF will report lower flow)

If your scan tool supports mode $06, post it here.

 

Have cleaned both MAF Sensors and swapped one out for a new one made no difference.

cats are both running the same temp so i thought this told us they werent blocked?

could it be the purge canister valve?

will run more tests shortly to advise the rest.

 

I have taken a video of what its doing see first post

 

Would love some help if anyone has any ideas to why this is running rich?

 

Since you didn't respond to my last post and are asking for additional help, I guess you feel I am not qualified to help.

Good luck in finding your issue.

 

Misunderstanding there, those replys were for you including the video.

not a very good scan tool so couldnt give you anymore info thats why i did video