Code question

[99screaminregal]

Been getting a P0171 code for a few months off and on. Got 122k mi. so went ahead and replaced the O2 sensor last week. Ran fine then it came back a few days later. Guy I know at AZ cleared the code. Well it came back. Looked all over the hoses and lines and all looks new. Went to http://www.wellsve.com (Auto Zone's electronics mf) and pulled the code up. It says O1 issue or fuel injector issue. I've heard LIM may be an issue too.

 

Any thoughts?

[Schurkey]

P0171 is a "lean (not enough fuel) condition".

 

Low fuel pressure/volume (plugged fuel filter, defective fuel pump)

Vacuum leak including manifold gasket problem

Partially-plugged injectors

Defective O2 sensor(s)

Fuel contamination

Air leak into exhaust including defective AIR system

Defective PCV

 

There are other things as well.

[99screaminregal]

Fuel pressure and pump were checked and tested a few months ago when it first started and had some other problems thought to be fuel related. O2, fuel filter, pcv all canted recently. And I use Lucas in the fuel regularly.

[Z34guy]

http://www.obd-codes.com/p0171

[Schurkey]

I use Lucas in the fuel regularly.

Certainly not my first choice.

 

If you need anything in the fuel, I'd suggest Chevron Techron, or the AC-Delco equivalent (Techron in a GM bottle)

Delco suggests a bottle of fuel system cleaner at each oil change.

GM Bulletins # 04‐06‐04‐051 and # 05‐00‐89‐078 for every oil change treatment recommendation

 

http://www.acdelcotechconnect.com/pdf/07TSS-135.pdf

ACDelco’s Fuel System Treatment Plus

ACDelco announces the availability of a 20 oz. bottle of Fuel System Treatment Plus, part number 10-3003 (88861013). This product is currently also available in a 12 oz. bottle, part number 10-3004 (88861262). ACDelco Fuel System Treatment Plus cleans and protects the entire fuel system from carbon deposits build-up and harmful sulfur contamination. ACDelco Fuel System Treatment Plus:

• Helps restore performance lost due to deposit build-up.

• Helps clean up deposits from:

o Port fuel injectors, which can restrict fuel flow and cause improper fuel injection operation

o Intake valves, which can cause poor drivability or difficult starting problems

o Combustion chamber, which can cause engine knocking, pinging and run-on in older vehicles or loss of power in knock sensor-equipped vehicles

• Can help clean sulfur corrosion from fuel sending units.

• Coats and helps protect all metallic surfaces of the fuel system.

• When used regularly, helps prevent fuel gauge malfunction caused by harmful sulphur components found in some gasoline.

• ACDelco recommends a bottle of ACDelco Fuel System Treatment Plus be added to the fuel tank at every oil change.

• ACDelco Fuel System Treatment Plus is the only fuel system cleaning preventative maintenance treatment currently endorsed by ACDelco for its gasoline engine fuel systems.

 

I don't know about you, but my Luminas go ~6,000 miles between oil dumps.

 

Techron has been on a "two for one" sale at O'Reileys auto parts recently.

[99screaminregal]

I think I'll go with the Techron and a MAF cleaning. Time for an oil change while I'm at it.

[AL]

A vacuum leak is usually the main cause of this code

[99screaminregal]

Well, light was off all day yesterday. Go figure. I noticed it on the way to work before I posted this. Probably will stay off for the next several miles until it wants to go off.

 

Put the cleaner in, gonna clean the MAF and spray every hose, insertion point, and any possible leak point on the top end. Hope I can find something. Hit every base I can.

 

And now the exhaust sounds plugged or blocked. Oh well, I got a do to help remedy that. Just need a 3in gasket to bring it together.

 

Just want to find he previous owner and whack them over the head. They must not know a damn thing about routine basic maintenance of a car.

[AL]

Its common for the cat to plug in these cars which would block the exhaust

[91luminaz34]

Well the first thing i would do is get a can of brakecleen or preferably something not flammable. Spray around throttle body and intake areas. also spray along all vacuum lines. Do this while engine is running listen for the engine to change rpm. you probably have a vacuum leak somewhere. if you have access to a decent scan tool look at your fuel trims. Very high fuel trims set this code to begin with. Engine is trying to correct a lean issue. Very rare that the o2 sensor is ever the fault. If fuel trims are very high at idle only you have a vacuum leak. Also hold rpm at 2200 to 2500 rpm, car in park, if fuel trims are lowest around that rpm range compared to higher and lower rpm you have a fuel issue. If they stay high all through rpm range or are only high at higher rpm I would suspect Mass air flow sensor issues.

[Schurkey]

Well the first thing i would do is get a can of brakecleen or preferably something not flammable. Spray around throttle body and intake areas. also spray along all vacuum lines. Do this while engine is running listen for the engine to change rpm.

If the spray is non-flammable, why would the RPM change?

 

The whole point of spraying chemical at a vacuum leak is so the vacuum leak draws the chemical into the intake system and the chemical burns with the air, richening the mixture and increasing the idle speed as a tell-tale. You WANT a flammable aerosol, such as aerosol carburetor cleaner.

[95 vert]

If the spray is non-flammable, why would the RPM change?

 

The whole point of spraying chemical at a vacuum leak is so the vacuum leak draws the chemical into the intake system and the chemical burns with the air, richening the mixture and increasing the idle speed as a tell-tale. You WANT a flammable aerosol, such as aerosol carburetor cleaner.

 

A non flammable spray (I use silicone spray) would not ignite on top of a hot engine. If you have a vacuum leak, it will "bog" the engine, dropping rpm.