Any help will be appreciated, i have a 2004 ford f-150 heritage 4.6 liter v-8 and i took my truck to advanced auto parts to have it scanned, it is saying that 02 sensor is running lean what does that mean??? i changed out the two on the passeger side with new ones (bosch), cause they said it was on bank 2 side so i tried the old ones that i replaced put them on the driver side bank 1, and it is still running like crap it has a very rough idle and it will sometimes stall at a redlight it like jumps rpms between like 800 -1000 back and forth almost dying should i buy 2 more and try it ???? or do u think it could be something else and the computer is playing games ?????? thank you

 

The computer is telling you that the gas mixture is too lean, this can be caused by a number of things, but the most common is air leaks that allow air in behind the MAF sensor. Check for bad vacuum hoses and the PCV valve first off.

 

A lot of things could cause your symptoms. What were the codes? Could be a dirty thottle body, vacuum leak, COP issues, spark plugs, etc.

 

thanks guys im checking this stuff out to narrow it down

 

Having the same problem with my 2004 Heritage 6 cylinder. Runs fine but when I come to a stop it surges jumps and acts like it still wants to go forward. I put it in park and it settles down. A car salesman said it was a computer chip that controls the throttle. What is the best recommendation I am a bust at fixing things but advice on what to do truck has 205,000 miles but still runs strong other than this issue.

 

Codes would help us help you. Any DTC's?

 

the codes are po171,p2197,po174 the man said this was probably front and back sensors located near the converter.

 

he recommended first trying to use sea foam to help clean off the carbon buildup if that does not help he said I could replace the sensors. What do you think?

 

other suggestion was a pvc valve was clogged and needed replaced? what your thoughts on this?

 

For any lean codes the first thing to check for is always vacuum leaks. You would be amazed how much money people have thrown at vehicles to avoid paying a shop for diagnostic services. Always check the simple stuff first before believing anyone that tell you to buy parts.

 

I would follow the diagnostic routine in the Emissions and Powertrain Control shop manual. Vacuum leaks are a possibility as well. Using the diagnostic routine in the manual will save both time and money.

 

where can I get a emissions and powertrain control shop manual? Also the seafoam I used seemed to really help the truck has improved on the surging issues at stops and idles.

 

thanks for the help on this issue. I am at a loss on checking the vacuum leaks where would I start to look? How many are there? Should just take it to a shop and ask them to check for vacuum leaks? So many shops just want to start replacing parts that I am not sure I need.

 

That's a great question. Without having access to the PTS website or working at a dealership I don't know where one would gain access to the Ford PCED. Perhaps digital copies are available for sale somewhere?

 

Listen for hissing noises under the hood, wiggle vacuum lines to see if noise/idle changes. Pay close attention to the intake gasket and PCV system. Can also use brake parts cleaner, carb cleaner or propane to locate. If the engine revs up while you're spraying an area it is getting into the engine. DO NOT get carried away if using a liquid spray! Use lightly in suspected areas only. Keep in mind that you're using something flammable on a running engine. My favorite leak detection tool is a smoke machine for EVAP systems but I'm guessing you don't have one of those laying around the house.

If you can't find any leaks that would be a good time to find a good diagnostic shop. Good being the key word there. I worked on a Taurus one time that the owner had at 3 different shops. They had put on a total of 6 02 sensors and a MAF sensor for a lean condition. 15 minutes monitoring fuel trims and then hooking up a smoke machine led me to his vacuum leak they never even looked for and I'm far from a genius. Those places apparently just didn't care.