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What would cause the fuel trims to improve with the air filter removed? The air filter isn’t forts. The trims look good without the filter in. When it’s it bank 2 goes to 23% at idle long term. But when it’s Removed bank 2 goes to 13%
The slight pressure drop across the filter would make a leak between the MAF and the throttle plate worse. That should affect both banks though. You only mentioned bank 2??
Yes sir. I found a few split vacuum hoses. Smoked the intake didn’t really see any smoke after the lines getting fixed. Can leaky exhaust manifolds cause a lean condition? It acts just like a vacuum leak. Goes from 25% long 15% short down to acceptable range at 2500 rpm. Reset Kam a few times. Maf reads 4.8 g/s at idle
Does it have the plastic intake? If it does look under the upper plenum and see if its leaking under manifold might be melted between the cylinders where egr hooks into intake. Or a booster leak/ torn or cracked or loose intake ducting from filter intake hose would be the only other thing I can think of.
What's the cam phasers position look like could be the intake phaser closing valves to soon or an intake manifold runner control rod clip broke off (not sure if the 5.4 has this or not)
Induce propane or vacuum leak into engine to test integrity of upstream o2 sensors. An exhaust leak in front of your upstream o2 sensor can cause a false lean condition on that bank. And these 5.4 liters like to break studs and develop exhaust leaks
Any obstruction ahead of the filter, something stuffed in the inner fender where the fresh air comes into the filter housing?
Is it the stock intake tube and filter housing?
If it is the stock one, is it in good condition? I've seen a couple of those big plastic ones mangled by people having a hard time aligning that big band clamp.
Checked air filter smoked it. Etc all good. But I think it’s down to a bad pcm. The actual vs scanner data of oxygen sensor is different. Multimeter shows full rich backprobed at pcm while pcm shows 300mv.
It’s not completely dead the front oxygen sensors. The pcm sees the change but definitely does not match the meter I have scoping the oxygen sensors at the pcm
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