Need some Suburban Help..

[rogerwa]

I have a 2004 Suburban that has been not running well in the cold lately. It runs rough and the RPM rises and lowers when warming up. I pulled the codes and it gives me a p0171 and p0174 which amount to bank 1 and 2 lean condition.

Anyone have any experience with this set of copes and common problems I should check for??

Thanks..

 

[DJ]

Re: Need some Suburban Help..

When is the last time you changed the fuel filter?

 

[rogerwa]

Re: Need some Suburban Help..

I have not changed it since new. However, it runs just fine once it is fully warmed up. While the filter may need changing, if clogged it would give me other driveability problems.. It seems as if the motor doesn't know its cold.

 

[SpinnerBait_Nut]

Re: Need some Suburban Help..

P0171

Fuel trim bank one condition
The powertrain control module uses the oxygen sensor to calculate the air/fuel ratio of the engine. The computer has recognized a rich or lean condition on one engine bank only.

Probable Causes

1. If bank one and two codes set together suspect fuel pressure or MAF (Mass Air Flow) Sensor
2. Oxygen sensor defective
3. Ignition misfire-repair
4. Fuel injector problem

P0174

Fuel Trim Bank Two Condition
The ECM has detected a rich or lean air/fuel ratio condition on engine bank two

Probable Causes

1. If bank one and two are set together suspect a fuel pressure condition or MAF sensor fault
2. Failed HO2S21
3. Ignition misfire condition
4. Fuel injector problem
5. Engine mechanical condition

 

[Reel Poor]

Re: Need some Suburban Help..

How many miles are on the vehicle? It's unlikely that it's an O2 problem on both banks. Seldom would you have a problem with two O2 sensors at the same time. It's also unlikely injector problems. If mileage is high 80,000+ it's time for a major tune up, plugs, wires, cap, rotor, fuel filter, and clean the throttle plate.

First I would clean the the throttle plate and replace the fuel filter. The lean condition is most likely related to a partially clogged filter and the surging idle is most likely due to dirty throttle plate. Air flow sensor is also a likely culprit and can be removed and cleaned with carb cleaner and compressed air.

BTW, poor fuel filter maintenance can and will cause premature fuel pump failure.

 

[rogerwa]

Re: Need some Suburban Help..

It has about 65+K on it.

 

[Reel Poor]

Re: Need some Suburban Help..

Tune up shouldn't be need for another 30 to 40K. But highly recommend doing the filter and cleaning.

 

[rogerwa]

Re: Need some Suburban Help..

Intake manifold gasket gets the prize.. $400 for R&R and $45 to update the software..