Both Banks Lean

[Alocoroco]

Hi all. Have a 16 GT having issue figuring out lean code. I’ve checked the hoses everything looks tight and solid, replaced the maf sensor and checked the air filter too. It’s still running lean on both banks. It sometimes also stalls when coming to a stop. Auto transmission, the stall doesn’t even feel like one it just dies then has to be restarted

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[ice445]

Check your intake manifold for cracks. A smoke test would be the professional way to find it. Do you have any codes?

 

[Alocoroco]

Check your intake manifold for cracks. A smoke test would be the professional way to find it. Do you have any codes?

171 & 174

 

[ice445]

171 & 174

I'd suspect the manifold if everything else has checked out, or one of the associated vacuum lines. But usually you'd see other codes in addition if other items are being impacted. I'm also assuming you verified good fuel pressure?

If you rev the engine up and watch fuel trims on a scan tool, do they get closer to 0 the higher the rpm?

 

[Alocoroco]

I'd suspect the manifold if everything else has checked out, or one of the associated vacuum lines. But usually you'd see other codes in addition if other items are being impacted. I'm also assuming you verified good fuel pressure?

If you rev the engine up and watch fuel trims on a scan tool, do they get closer to 0 the higher the rpm?

I haven’t checked the fuel trim, it won’t be oxygen sensors?

 

[ice445]

I haven’t checked the fuel trim, it won’t be oxygen sensors?

Doubtful, unless both are severely fouled out (or both banks have severe exhaust leaks but this usually trips another code as well) Is this car modified?

 

[Alocoroco]

Doubtful, unless both are severely fouled out. Is this car modified?

Bone stock

 

[Alocoroco]

I'd suspect the manifold if everything else has checked out, or one of the associated vacuum lines. But usually you'd see other codes in addition if other items are being impacted. I'm also assuming you verified good fuel pressure?

If you rev the engine up and watch fuel trims on a scan tool, do they get closer to 0 the higher the rpm?

What happens if the fuel trim gets close to 0?

 

[ice445]

What happens if the fuel trim gets close to 0?

It's supposed to be as close to zero as possible. Lean codes trip at +24% or so. If the percentage decreases at higher rpm then it's indicative of air getting in past the maf

 

[Alocoroco]

It's supposed to be as close to zero as possible. Lean codes trip at +24% or so. If the percentage decreases at higher rpm then it's indicative of air getting in past the maf

That would indicate a air leak then correct? And if it doesn’t do that then will it be the sensors?

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