4.0 OHV identifying california emissions and advice on high idle/lean codes

[Michael Rogge]

Was suspecting that my engine needed new o2 sensors, according to rockauto they are different for cali and fed emissions. Attached are some pictures of relevant markings. Note that I don't know if the radiator support is original, the vehicle was in a front end collision a few owners ago as far as I can tell and the support is black when the truck is green. There is a very EGR-looking device between the exhaust manifold and intake, though if it is indeed an EGR that is a stupid design to put the EGR before the MAF and air filter.

I also have codes 172 (lean bank 1), 176 (lean bank 2), 136 (not switching bank 2), & 411 (KOER low speed idle test fail), what are the most common problems to cause this?

 

[Shran]

High idle & lean codes really point to a vacuum leak in my mind.

That deal on the air snorkel is not EGR, it's basically just a little valve that allows hot air off the exhaust to get pulled into the engine in cold weather.

 

[gaz]

@Michael Rogge
I would verify the fuel pressure on the rail immediately after shut down, then again after not running for 12-ish hours ..)

 

[Michael Rogge]

@Michael Rogge
I would verify the fuel pressure on the rail immediately after shut down, then again after not running for 12-ish hours ..)

What is the fuel pressure supposed to be for this engine? Should I check it when running as well?

 

[Michael Rogge]

High idle & lean codes really point to a vacuum leak in my mind.

That deal on the air snorkel is not EGR, it's basically just a little valve that allows hot air off the exhaust to get pulled into the engine in cold weather.

Glad to hear it’s not an egr
Was kind of hoping it was o2 sensors since those are a lot easier than intake gaskets (I already checked all the lines and none seem to be leaking), you’re probably right though

 

[gaz]

@Michael Rogge
Should read 38 while running, immediately after shutdown and 12 months later, even if the vehicle sat that long without being started or driven.