I have a 2001 Suburban with a couple of codes.. P0171 and P0174. I read a lot about these codes but nothing has worked. This is what I've done.....

Injectors cleaned, All new O2 sensors, Changed Crankshaft Position sensor, Cleared ECM, Changed the MAF sensor, Cleaned the throttle body, Changed Ignition relays, Changed the TPS, checked all vacuum lines, cleaned/check PCV valve, Sprayed 2 bottles of carb cleaner looking for a vacuum leak. Changed spark plugs, I'm going to try the fuel filter next, PCV valve, and maybe the fuel regulator. The truck idles fine just sitting there but under load it stumbles and stalls, going up hills at full throttle.

Once I figure this thing out I shouldn't have a problem for a while since I've replaced and cleaned everything on this motor.

Can I get some suggestions please....

Thanks

 

Fuel Trim too lean bank 1 and 2

Do you have any modifications to the truck?

 

No mods.

 

run some of that chevron injector cleaner in you gas tank....or whatever brand of good i cleaner you can find....

 

no mods. My first "guess" is the same as bud, clean those injectors. A 2001 with how many miles? O2's with alot of miles can be a culprit all on their own as well.

 

The first thing artmolina mentioned was that he cleaned the injectors and replaced the O2 sensors? Anyway it should not hurt to run some chevron cleaner through a tank of gas.

After you replace the fuel filter check the vacuum line at the fuel pressure regulator after you have had the suburban out for a drive. If there is any sign of fuel at the vacuum line then the FPR is bad and will need to be replaced.

If you still get the codes then have the fuel pressure verified at the port on the fuel rail both at idle, cruising and at WOT. Idle should be around 52-54 psi, deceleration 49 psi, general driving 54-58 psi and WOT 62+ psi.

I think exhaust leaks before the front O2s can cause bad O2 readings as well.

Good luck.

 

DOH! LOL See, missed that. Yep, exhaust leak will show as lean, but should make you run rich.

 

My first thoughts were FPR.

 

agreed, i think it might be a fuel pressure issue. Check the fuel pressure and report back.

 

woo slow down there with the parts. most of the time these codes are set from the intake gaskets leaking. you can't find it with carb cleaner. i have done a lot of these gaskets at the shop. go there next.