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Hey I got error codes p0300, p0301, p0302, p0303...
Its a real mess I guess because it can be so many things...
I just changed the MAF but this didnt help... I've added Fuel injec cleaner, didnt work. So I started to think about the O2 sensors... And I read them off, just need some help to read them as I have low knowledge of this.
What do you think of these readings? When I restart the car its fine, until I accelerate, and it starts to shake and goes off on cylinders. Turning it on and off again its fine until acceleration, also happens in gear PARK when I take down the pedal to about 3000+ rpm. I looked at long term bank 2 and was seeing its only negative? what does that mean? and the long term always positive..? add and sub gas? need some professional help
So misfire on whole bank of V6.
I would look for what is common to that bank and start there.
I had a like problem and it was one bad injector (very rare).
When searching I found a bad cat can do that as well.
Good luck!
Ok, so I've read the voltage of the o2 sensors, bank 2 seems to be fine....
When I read bank 1, the 1st sensor is fine and the 2nd sensor is jumping all over.
So this tells me that i need to replace the catalytic converter bank 1.
So if the catalytic converter on bank 1 is failing... this will affect only cylinder 1,2,3?
and not 4,5,6.. ?
Ok so now I've changed all the 6 pluggs on bank 1. cyl1,2,3
And swapped the coils from 1 side to the other. No fix
90% sure its the cat, gonna deliver it for a diagnose tomorrow and see if i'm right.
Want to be sure before I put in money on a new cat, and the problem beeing fuel injector... xD Ill reply tomorrow.
I just came across this exact same issue with the S430 that I'm resurrecting. I replaced the engine and fired it up....got the same error codes.
NEVER did an error code come up for a Catalytic Converter.
I did the swapping of the coils, but then thought...this engine worked fine before I installed it....it has to be the car, not the engine.
I had some extra parts laying around and cut the front catalytic converter out and put in one that I knew was acceptable. The front cat was all broken up on the inside. I reconnected it with an beginner's MIG weld job on the final connection (while installed and missing the top of the pipe) and started it up again. This time....getting a fairly loud hissing sound coming from my last connection (because it was not a good weld it was leaking).
And, at that point, the "lightbulb turned on".
The rear converter was totally clogged with the debris from the front converter causing ridiculous back pressure.
This back pressure was causing the misfires and only on the one bank.
I cut out the rear converter, tacked in another known working converter and put it back together. Fired it up and is running great!!!
Clogged rear Catalytic Converter caused by front Catalytic Converter breaking apart
Last edited by The Shoeman; 11-30-2016 at 07:32 PM.
Reason: typo
I just came across this exact same issue with the S430 that I'm resurrecting. I replaced the engine and fired it up....got the same error codes.
NEVER did an error code come up for a Catalytic Converter.
I did the swapping of the coils, but then thought...this engine worked fine before I installed it....it has to be the car, not the engine.
I had some extra parts laying around and cut the front catalytic converter out and put in one that I knew was acceptable. The front cat was all broken up on the inside. I reconnected it with an beginner's MIG weld job on the final connection (while installed and missing the top of the pipe) and started it up again. This time....getting a fairly loud hissing sound coming from my last connection (because it was not a good weld it was leaking).
And, at that point, the "lightbulb turned on".
The rear converter was totally clogged with the debris from the front converter causing ridiculous back pressure.
This back pressure was causing the misfires and only on the one bank.
I cut out the rear converter, tacked in another known working converter and put it back together. Fired it up and is running great!!!
Clogged rear Catalytic Converter caused by front Catalytic Converter breaking apart
Ok so I changed the right catalytic converter today, works like a charm. But now I got another issue, when I punsh it it can take out p0304, p0305, p0306, Im sure the cat is perfect as I've run tests on it. Can it be the spark plugs be old on that side that it can missfire under heavy load when i do kickdown and drag it out to max rpm?
Just curious , did you clear the error codes after the converter replacement ,
Did you replace both converters on the right side?
you stated you changed the plugs already in a previous post so I'm not sure if that's it but if you were having misfires on the new plugs, that might have damaged the plugs,.. .but I'm only guessing on that. what do others think about this guess?
Just curious , did you clear the error codes after the converter replacement ,
Did you replace both converters on the right side?
you stated you changed the plugs already in a previous post so I'm not sure if that's it but if you were having misfires on the new plugs, that might have damaged the plugs,.. .but I'm only guessing on that. what do others think about this guess?
Hey!
Yeah i changed both cats on the right.
cleared codes before change.
Did only change the plugs on bank 1 i ordered the rest so we will see
11-25-2016, 04:01 PM
i ordered the rest so we will see 
