Persistent P0420 and P0430

[swathdiver]

Well this isn’t good. Powdery white ground strap. I know these are supposed to be frugal with fuel but not this much. But explains a lot. Gonna go in and reset the fuel trims and alcohol percentage to see if it relearns.

Do all eight look like that? 2007s are a pain because they don't have a separate fuel pump module, have to use manual gauge.

Have you replaced the intake gaskets?

Do you have any exhaust leaks around the manifolds or at the connection between the manifolds and y-pipe?

You have a massive vacuum leak somewhere and it is killing your cats.

What brand of new cats did you go with? Cheap Chicom cats are lucky to last a year even with everything running fine.

 

[Cj6706]

Just checked the one and stopped. Wasn’t what I expected to find and got a little ticked off. Haven’t messed with the intake. Gonna check that tomorrow with some starting fluid. But wouldn’t a vacuum leak give me positive fuel trims?

Went with the Walker cats/h pipe assembly. No leaks that I’ve seen or heard.

 

[Cj6706]

Well didn’t don’t any leaks in the intake system. Hooked up a smoke machine and the only place any smoke ever trickled out was the air filter. Nothing from the intake or the piping. Drove around and fuel trims were between -18 and -21. I reset the trims and it goes right back. Not seeing anything on live data to justify it pulling so much fuel out. MAF seems to be correct and adjust for throttle position. The one thing I couldn’t figure out was the PSI reading on the MAP. Is it supposed to be positive? Is it in relation to the barometric pressure value? I need to research this. At idle it’s around 5.5 psi and goes up with speed. But when I get on it the value still goes up. I would expect it to be high at cruise and a little lower at idle. But I also would expect it to drop when I get on it. No? Frustrating. Don’t want to burn a hole in a piston. Where to next? Thanks all.

 

[MrBishop]

Well didn’t don’t any leaks in the intake system. Hooked up a smoke machine and the only place any smoke ever trickled out was the air filter. Nothing from the intake or the piping. Drove around and fuel trims were between -18 and -21. I reset the trims and it goes right back. Not seeing anything on live data to justify it pulling so much fuel out. MAF seems to be correct and adjust for throttle position. The one thing I couldn’t figure out was the PSI reading on the MAP. Is it supposed to be positive? Is it in relation to the barometric pressure value? I need to research this. At idle it’s around 5.5 psi and goes up with speed. But when I get on it the value still goes up. I would expect it to be high at cruise and a little lower at idle. But I also would expect it to drop when I get on it. No? Frustrating. Don’t want to burn a hole in a piston. Where to next? Thanks all.

"New K&N panel with the excess oil wiped off." Is this a KN air filter? If it is, that is the problem. The programming is set up to model the air flow of a production filter. When you put the KN ones on, you need to adjust this model. Sometimes it won't even start like in the case of the 55 Chevy EROD I tuned for Chevy Performance.

 

[Rocket Man]

"New K&N panel with the excess oil wiped off." Is this a KN air filter? If it is, that is the problem. The programming is set up to model the air flow of a production filter. When you put the KN ones on, you need to adjust this model. Sometimes it won't even start like in the case of the 55 Chevy EROD I tuned for Chevy Performance.

Not true. That’s what the MAF is for, it measures the amount of air being drawn through the filter. It’s installed post filter, not pre filter. The only issue we have with a oiled filter like the K&N is if too much oil is applied and it gets onto the sensing wires of the MAF.

@Cj6706 when you say “excess oil wiped off” , how much oil did you apply? There’s a specified amount of it according to the filter part # and it needs to be the correct type, sprayed evenly onto the filter. There should be no excess to wipe off. If you are getting oil onto the MAF you’re going to have all kinds of issues.

 

[MrBishop]

Absolutely true. The MAF measures an electrical signal. Explain how it takes an electrical signal and converts to an airflow value. That is what the table does, and it is based on the flow of the filter. I did many of these in the car and on a flow bench at GM.

 

[CaptainAmerica1]

FNG lols

 

[Rocket Man]

Absolutely true. The MAF measures an electrical signal. Explain how it takes an electrical signal and converts to an airflow value. That is what the table does, and it is based on the flow of the filter. I did many of these in the car and on a flow bench at GM.

You can run an oiled filter on an LS with stock tuning tables just fine. There’s plenty here who do that. There’s also plenty here who remove the entire resonance chamber/ intake tube and install a cheap CAI with an even cheaper oiled filter with a stock tune with zero issues. There’s nothing needed to change in the tables to accommodate either one.

 

[avalonandl]

I would put a paper AC air filter in the car....

 

[CaptainAmerica1]

I would put a paper AC air filter in the car....

ROFL thanks for contributing!!