2011 running poorly...

[camperhead]

P0420 and P0430 are cat specific codes. If you can see your sensors with a scan tool, the downstream O2 sensors, those behind the cats, should read fairly constant. If they are moving like the upstream O2 sensors, then you know the cats are not doing their job anymore.

Save your old cats and sell them to the scrap man, retail scrap price for a GM cat is about $75 and you have three.

The only active code it is throwing P0300. Cylinder 7 has alot of misfire activity... Cylinder 7 is not a DOD cylinder correct??

It did show P0420 and P0430 in code history however....


Both banks downstream show a consistent high value...

Thoughts?

 

[camperhead]

P0420 and P0430 are cat specific codes. If you can see your sensors with a scan tool, the downstream O2 sensors, those behind the cats, should read fairly constant. If they are moving like the upstream O2 sensors, then you know the cats are not doing their job anymore.

Save your old cats and sell them to the scrap man, retail scrap price for a GM cat is about $75 and you have three.

Only active code I have is P0300. Cylinder 7 is mis firing WAYYY worse than others.

I do have P0420 and P0430 in history codes.... both downstream O2 sensors are showing consistent high value though.

Any Thoughts

 

[BG1988]

Only active code I have is P0300. Cylinder 7 is mis firing WAYYY worse than others.

I do have P0420 and P0430 in history codes.... both downstream O2 sensors are showing consistent high value though.

Any Thoughts

if the value is high its running rich
check the air filter
clean the MAF with MAF cleaner


check the basic things first


P0300 is random misfire
P0307 is #7


don't worry about the p0420 and p0430 they have 40-45 enable conditions

 

[swathdiver]

The only active code it is throwing P0300. Cylinder 7 has alot of misfire activity... Cylinder 7 is not a DOD cylinder correct??

It did show P0420 and P0430 in code history however....


Both banks downstream show a consistent high value...

Thoughts?

Number 7 IS an AFM cylinder. Pop the valve cover and have a look. Did you get the CANdi working or a new one?

 

[camperhead]

Number 7 IS an AFM cylinder. Pop the valve cover and have a look. Did you get the CANdi working or a new one?

What am I looking for undervalve cover???? watch rockers to see if lifter is collapsed?


I ordered a new CANdi off amazon. In mean time I borrowed a snap-on from a buddy. should have new CANdi monday. We are taking this truck on trip soon and I want to start making head way on figuring it out...

 

[swathdiver]

What am I looking for undervalve cover???? watch rockers to see if lifter is collapsed?


I ordered a new CANdi off amazon. In mean time I borrowed a snap-on from a buddy. should have new CANdi monday. We are taking this truck on trip soon and I want to start making head way on figuring it out...

Yes, to check for a broken valve spring or collapsed lifter. You can also see if it has the updated valve cover that reduces oil consumption, should be 12642655.

 

[Derick]

I'm surprised no one said anything about the coil packs? This behavior happened to my on my old crown vic with COPs and it finally threw a code and found which cool had died.