catalytic function not clearing (should I do more parts cannon)

[Fernando Escobar]

Hey guys So I went to do a smog in early Jan and it failed because the Catalytic Converter diagnosis is not ready. I cleared the ECM multiple times disconnected the battery and have driven the truck over 500 miles now to no avail.
It is cammed and I need to clear a P0300 that bugs it with a tune, but this has never impacted my smog check once the CEL goes away. But the Cat light staying on red is new to me.

Should I just bite the bullet and change the O2 sensor?

It seems like bank 1 has been the worst one. When I check the missfire data it seems like 7 is the worst offender.
I'm just trying to get it passed smog for now and have two years to tune it and fix the other issues I did not do the first time around.

All sensors were changed around 2014 and I used the Bosch sensors. I know there was talk about it was better to use the Denso (OEM) sensors.

When I cammed this truck I had to chage heads and used my original valves which i did not lap so im sure small leaks are occuring and cuasing compression issues, and I never accurately measured my push rod length going from LS1 to LS7 lifters. so this will need to be addressed once I finish my L94 update (and yes these items are on the checklist this time).

 

[swathdiver]

Well, you should use your scan tool to see how the sensors are performing. The cat could be bad as well. Even new ones go bad, especially the Chicom ones.

If you want your engine to run in top form, do not use aftermarket sensors, not even Denso unless it comes out of an ACDelco box/bag. They are still different.

 

[Fernando Escobar]

Well, you should use your scan tool to see how the sensors are performing. The cat could be bad as well. Even new ones go bad, especially the Chicom ones.

If you want your engine to run in top form, do not use aftermarket sensors, not even Denso unless it comes out of an ACDelco box/bag. They are still different.

the Cats were switched out in 2018, Being in California that's going to cost me an Third Kids college tuition to replace them again lol.
When I look at the data the Short Term fuel trims are all over the wall. The spark Plugs are a bit carbonated which if I am can be a lean condition right?
I had put some AC Delco platinum's on it but I was shocked at how bad the gap was on them. I tried my best to re-gap them some were to wide some not enough. So I have some Denso TT's on standby to swap in.
Denso has been good to me and my friends trucks I have replaced (at least 4 Tahoe/Silverado's now). After joining this forum years back I learned that Bosch was not the best way to go.
After these spark plugs I learned to avoid Amazon for car parts like the plague especially if it's not amazon directly selling them

 

[Scottydoggs]

that p0300 is never going away once you got a cam, it needs to be tuned out, every time you clear codes you make every system gets cleared and everything needs to relearn again until they all say ready.

whats the code/codes your getting? id think 5 year old cats should be good still.

you could buy a hptuners for like 400 bucks, delete the p0300 and maybe get away with deleting the o2 codes if any codes for them are popping up. cats can take some time to become ready, just like the evap that generally takes the longest.

ca can now see if emissions stuff is deleted. id think they are only looking for evap, cats and egr's to be ready and not deleted. but not living there im not 100% sure on that.

 

[Fernando Escobar]

that p0300 is never going away once you got a cam, it needs to be tuned out, every time you clear codes you make every system gets cleared and everything needs to relearn again until they all say ready.

whats the code/codes your getting? id think 5 year old cats should be good still.

you could buy a hptuners for like 400 bucks, delete the p0300 and maybe get away with deleting the o2 codes if any codes for them are popping up. cats can take some time to become ready, just like the evap that generally takes the longest.

ca can now see if emissions stuff is deleted. id think they are only looking for evap, cats and egr's to be ready and not deleted. but not living there im not 100% sure on that.

its the generic hp p0300.
But the cat monitor is still red.
Even with the p0300, it would turn green other years. This year it's staying on red after 500 plus miles of driving. that's why I'm considering throwing a a new O2 Sensor. after it clears and passes I want to remove the heads to lap the valves and maybe change to a better known cam. Im considering buying the HP Tunners and play around with it.

 

[Scottydoggs]

are you able to scan live data with your scanner? if you can scan the o2's all in Mv and normal voltage. on normal volts at idle and in general they should be moving up and down constantly and rather quickly. Mv when your driving it, and go wot the up streams o2's (banks 1 and 2, sensor 1 on both banks. sensor 2 is the post cat o2)should hit like 930 ish and lock there till you lift the gas. if they are not making to upper 800's and or fall off not being locked in, that o2 would be lazy or just dead o2, but not dead enough to set a code.

like others said, stick with ac delco sensors.

 

[Fernando Escobar]

are you able to scan live data with your scanner? if you can scan the o2's all in Mv and normal voltage. on normal volts at idle and in general they should be moving up and down constantly and rather quickly. Mv when your driving it, and go wot the up streams o2's (banks 1 and 2, sensor 1 on both banks. sensor 2 is the post cat o2)should hit like 930 ish and lock there till you lift the gas. if they are not making to upper 800's and or fall off not being locked in, that o2 would be lazy or just dead o2, but not dead enough to set a code.

like others said, stick with ac delco sensors.

I can on my smaller Autel I will check it out

 

[TollKeeper]

Cam = Needs a tune!

 

[swathdiver]

I missed what the fellas caught onto, that you have an aftermarket camshaft and did not tune your truck for it. Of course she throws the code and will never be emissions ready.

I don't think an O2 sensor is going to fix that one. A BlackBear tune will.

I also replaced my cats in 2018, almost 6 years and 75K miles, no problems so far.

 

[nonickatall]

The o2 sensors can be result of your problems not the cause.

To find out if your o2 sensors are the problem, why don't you change the left side sensors to the right side. Than you know if your problem is moving as well.

You can also check o2 sensors..