po171 & po174

[2Sluggos]

I have a 2003 suburban 5.3 and I'm getting bad mileage and po171 and po174 codes. (bank 1 & bank 2 is lean) any ideas? MAF sensor was replaced 2 months ago.

[MT-2500]

Originally Posted by 2Sluggos

I have a 2003 suburban 5.3 and I'm getting bad mileage and po171 and po174 codes. (bank 1 & bank 2 is lean) any ideas? MAF sensor was replaced 2 months ago.

Start with a good fuel pressure check.
Also fuel filter.
Any vacumn leaks or sucking air any place?
Post back fuel pressure readings.
How many miles and last good tune up?
Any other codes or engine missfires?

Has codes been cleared and see what returns?

[j cAT]

Originally Posted by 2Sluggos

I have a 2003 suburban 5.3 and I'm getting bad mileage and po171 and po174 codes. (bank 1 & bank 2 is lean) any ideas? MAF sensor was replaced 2 months ago.

fuel pressure should be 53-62psi. the fuel filters need replacing around 30-40,ooomi..usually this fuel pressure issue , would cause poor/slow start...

both banks lean gets into intake leaks,vacuum lines,air ducting from maf to the throttle body leaking...

If you use an oil on your air filter , this may need the MAF cleaned , with MAF CRC MAF CLEANER.

intake gaskets are a very common problem...I use propane to find intake leaks. small torch with a rubber hose connected the the end..with gas turned on very low probe gasket areas for a rpm rise..

the idle air control will drop idle so with too much propane you can make this test for a leak harder , as the IAC will inhibit rpm rise..


what is your idle in drive/neutral ? should be 600-650 rpm...

if higher this would be vacuum leak[s]..

[usamarshal]

Are you losing any coolant?