Intermittent code p0171 and p0174

F

FTC

Just a dumb welder
Dec 18, 2012
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Hawaii
Sup guys I have a 02 4.8 RCSB. Over the past few months I've been getting random p0171 and p0174 both banks lean codes. It'll be on for a few days then go back off, my initial thoughts were vacuum leak. But I cant find one, I've changed MAF, intake and throttle body gaskets, and the evap vapor purge solenoid(I have the canister solenoid but I think that would be unrelated to the codes). Then I looked at possibly a fueling issue so I changed fuel filter, and the reg. Im getting 50psi key on/engine off and holding for 10+ minutes so I think the fuel pump is ok. The manual calls for 55-62 psi KOEO is the 5 psi low enough to throw codes? Any help is appreciated, thanks


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I had to put my stock manifolds back on for smog and take my long tubes off.
Where my manifolds connect to my Y Pipe, I definitely have an exhaust leak, before both front 02's. Throwing a p0171 and p0174.
Check for exhaust leaks
 
Moore said:
Usually leaky intake manifold gasket

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Changed them out to the updated teal ones, I don't think they were leaking before anyway tho


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j.mo said:
I had to put my stock manifolds back on for smog and take my long tubes off.
Where my manifolds connect to my Y Pipe, I definitely have an exhaust leak, before both front 02's. Throwing a p0171 and p0174.
Check for exhaust leaks
Click to expand...

Sounds like you may be right, I do have LTs and a small exh leak. I will check that out thanks


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I'm getting p0171 without the p0174 cleaned the maf a couple days ago hasn't come back hope all is good, any ideas why only p0171 would come up?


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