Rough Idle & P0171 + P0174. Vacuum leak?

[Lapister]

Those 2 codes are referencing both banks 1,2 lean condition. Hissing does sound to be most likely vacuum leak after the maf. Did you check the hoses between the T and plenum? You are most likely introducing unmetered air thru a leak

[geraintthomas]

Originally Posted by Lapister

Those 2 codes are referencing both banks 1,2 lean condition. Hissing does sound to be most likely vacuum leak after the maf. Did you check the hoses between the T and plenum? You are most likely introducing unmetered air thru a leak

Already checked the codes and found that it meant too much air, so I've suspected a leak. I've checked the hoses, all seems okay. The hissing sound seems to be coming from here:



That's why I was thinking it may be that little valve on top, but I'll check. I'm going to take the engine cover off behind the seats to get a front-on look at the engine to see if I can see anything else.

The other thing is that I may be chasing a leak that doesn't exist. The sound could be normal, and it could be something else causing the codes and rough idle.

What could it be?

[thstone]

Originally Posted by geraintthomas

What could it be?

- Failing MAF
- Intake system air leak
- Low fuel pressure
- Low fuel volume
- Bad fuel injector(s)
- AOS failing
- Oil filler cap leaking or oil fill tube cracked and leaking

[geraintthomas]

Originally Posted by thstone

- Failing MAF
- Intake system air leak
- Low fuel pressure
- Low fuel volume
- Bad fuel injector(s)
- AOS failing
- Oil filler cap leaking or oil fill tube cracked and leaking

I'm aware of the symptoms - it's not fuel as it's fine under load, it's not the MAF as I've tested it, it's not the oil cap as the engine stalls when removing it.