O2 Sensors Or Catalytic Converter
 

Hi guys,
So I had to replace my catalytic converter about 6 months ago, I had a P0422 Error code and the check engine light was on. I took it to a mechanic and they hooked up their OBD tester and confirmed that the Post and Pre O2 Sensors seemed to be nearly identical therefore this lead us to believe the Cat was at fault.
After I fitted the new Cat the code was cleared and the light stayed off for a good 1000 miles. Then all of a sudden one day it popped back on again whilst driving down the motorway, i decided to get a code reader of my own and Torque Pro app, the same error code was back and O2 Sensors showed the same thigng as before, I have attached 2 images, one when the car is first started and the other just after my journey into work.
Do you guys think it is the Catalytic converter?
it's under warranty but the place I bought it said i would need to produce and emissions test certificate to prove it isnt working correctly.
I Spoke to an MOT place and they said even an emissions test wouldn't be conclusive that it's a faulty Cat.

My car is a Hyundai Coupe/Tiburon 2.0l 2001 Gen 2
https://cimg0.ibsrv.net/gimg/www.hyu...0fa7e2a647.jpg
After Journey
https://cimg2.ibsrv.net/gimg/www.hyu...84effaa48f.png
Upon Starting

Thanks Guys,
Nayth

Something to keep in mind.
Cats don't often go bad by themselves, there is an underlying reason. Replacing a destroyed cat without correcting the original problem is throwing away good $$$.

Most of the time an over rich condition will overheat the cat and eventually destroy it. I suspect that is what happened. There is more to diagnosis and repair than most folks realize. You might want to look more carefully at your fuel trims and see what is going on. You have found the result ,but not the root cause.

So i wasnt too sure which Fuel Trim sensors to use for my journey home, can you suggest any others to. add or take away unnecessary ones?

https://cimg8.ibsrv.net/gimg/www.hyu...030fa62723.png

Hi there, thanks for your response.
It seemed to produce more readings this morning, numbers provided too.
https://cimg8.ibsrv.net/gimg/www.hyu...948d0c1f1d.png
https://cimg4.ibsrv.net/gimg/www.hyu...d35db42999.png
https://cimg6.ibsrv.net/gimg/www.hyu...67731f69a6.png

Something is causing the long term trim to add fuel which is seen by the high long term numbers.
Everything seems fine on starting, but after running it is adding too much fuel .
Don't know what engine is in your vehicle or if it has a MAF sensor.
Can you supply that info?

Heya sounds like we are getting somewhere, yes the engine is a 2.0l 16v and it does have an MAF sensor, i have been a little suspicious whether it is working properly.
As an additional note the engine does get a little jittery and choppy sometimes, not sure if that is what's called a rough idle? But when the car has been running a little while and I go to stop in traffic or at a red light I go down to first gear and press the clutch, it struggles to keep revs and has stalled on a few occasions. It sorts itself after a little while but it makes for an unnerving experience.
https://cimg7.ibsrv.net/gimg/www.hyu...caceaac7ae.jpg

From what I was able to see, when starting the fuel trims and o2 sensor rdgs are ok. Then something happens and they go banannas.. Can you get the MAF rdgs and engine RPM ? I there a way your tool will provide a listing of what is called data stream ?
That way I can see what all the numbers are at one time without having to hop around trying to look at the graphs ?

Thank you Hanky, are you looking for actual video data or just numbers of all these things at the same time, I looked for the option of data stream but nothing matched the criteria.
Is the attached a good example of what you need?
Then I could rev the engine to certain points and take several screenshots?
https://cimg5.ibsrv.net/gimg/www.hyu...f6857b5d6f.png

Those last 5 readings are better than nothing, however, when watching the data stream I am able to observe ;
Engine temp
RPM
Battery volts
Inj pulse width
O2 volts
Fuel trims
MAF rdgs
TPS
Engine load
and many others in real time to see exactly what is happening and how they affect one another.
The info you are providing is great to observe a detailed picture of an area, but to me is incomplete.
It may be just a guess, but maybe you don't know the full capabilities of your tool.

Picture when your physician looks at a patients blood work, he/she knows just what all the normal rdgs should be and has them all in front to see and compare.
Diagnosing automotive readings is pretty similar..

I will have a look through other apps and see if they can provide all of this in one tidy place.
I'm guessing the best way to show you after would be a video recording too is that correct?