CODES THAT DRIVE ME NUTS

[caddypete]

I get a serice engine soon light on any given day,replaced the o2 sensor in bank 1 didn't change anything.So I will give the problem to you fine gents.Here it is can start car and pull codes there are none when cold,as soon as it hits operating temp there is a stumble, pull codes fuel trim lean bank 1, no service engine light.get on freeway drive for 20 miles, pull codes fuel trim lean bank1, and P1133 HO2S insuffcient switching bank 1 sensor 1. no SES light on, clear codes,Park car for 2 hrs get back on freeway pull codes,P0171 again, clear codes drive 10 miles SES light comes on P0171,P0131 and P1133. clear codes light goes off,sometimes stays off other times keeps on lighting right after being cleared,P0171 on the codes.If I drive my short ride to work days, 2 miles no codes,but car never gets over 1/4 on the temp gauge before it's parked.I thought it was a o2 sensor, but I have changed that and no difference, it seems it has to hit operating temp to set code,I cannot figure out what the problem is,have checked for any leaks in inake system can't find any.Also my buddy was following me one day and said I'm blowing black smoke out the exhaust, I have noticed the exhaust smoke when I nail it,but he said it is blowing black smoke most of the time.To me that means the engine is running rich but codes are telling me differently.I have checked plugs on front bank (bank 2) they are white.Have not pulled the rear bank yet, car was warm and I have to climb on engine to get to those.Anyone got any thoughts?fuel filter has been changed also air filter recently.Throttle body cleaned and EGR valve also.On a fuel pressure test 39 lbs at idle.

P0171 - Fuel Trim System Lean Bank 1

P0131 - Heated Oxygen Sensor (HO2S) Circuit Low Voltage Bank 1 Sensor 1

P1133 - Heated Oxygen Sensor (HO2S) Insufficient Switching Bank 1 Sensor 1

[Logan]

Something is causing the rear bank to be lean..

Check for the following conditions:

• HO2S wire routing -- The sensor wiring may be routed incorrectly and contacting the exhaust system.

• Fuel pressure -- Fuel pressure that is too low will cause a lean condition. The PCM will compensate for some decrease. However, if fuel pressure is low enough, DTC P0131 may set.

• Fuel injectors -- If the fuel injectors deliver improper fuel volume at the specified pressure, DTC P0131 may set. Refer to Fuel Injector Balance Test with Tech 2 .

• Exhaust leaks -- Exhaust leaks may cause outside air to be drawn into the exhaust gas stream, and pass the HO2S sensor. This causes the HO2S signal to indicate a false lean condition.

• Vacuum leaks -- Check for the following:

- Disconnected or damaged vacuum hoses

- Vacuum leaks at the throttle body, EGR valve, EVAP purge solenoid, and intake manifold

• Fuel contamination, refer to Alcohol/Contaminants-in-Fuel Diagnosis . Water, even in small amounts, can be delivered to the fuel injectors. The water can cause a lean exhaust. Also, excessive alcohol in the fuel can cause a lean condition.

If the condition is intermittent, refer to Intermittent Conditions in Symptoms.

If none of the above conditions are present, replace the HO2S sensor. Refer to Heated Oxygen Sensor (HO2S) Replacement Bank 1 Sensor 1 .

Review the front and rear long term fuel trim values on the scan tool fail records data. If both banks were lean, check for a condition that would cause a lean engine operation. If only the rear bank was lean, the lean condition is isolated to that bank (such as an intermittent short to ground on the signal circuit).

[Ranger]

Don't overlook the FPR. Very easy to check.

[caddypete]

I have a notion that it is temp related,don't know if there is a relay that opens at a certain temp maybe EGR valve.But I can tell when it sets the code because there is a stutter in the motor for a second right about when it hits operating temp then the bank1 lean shows up also the tach wil flucuate when coasting or when you hit the brake it will drop to 700 rpm and then stabilize at 1000.As you can tell I have been toying with this for awhile.It is confusing because it doesn't always set the SES light,but when it does then it will keep the SES light on even when you clear the code, if you stop and shut it off the light doesn't come back on but the code is present

[JohnnyG]

And remember to NEVER put silicone grease or anything on the O2 sensor wires. The sensors pull the reference sample of oxygen THROUGH the wires, anything that inhibits that action will render the sensor inoperable.

[Ranger]

And remember to NEVER put silicone grease or anything on the O2 sensor wires. The sensors pull the reference sample of oxygen THROUGH the wires, anything that inhibits that action will render the sensor inoperable.

HUH? How does it pull O2 through wires?

[adallak]

Some info concerning oxygen sensors:

http://auto.howstuffworks.com/framed.htm?p...ts.com/o-21.htm