Lean Codes

[mille1cw]

I've replaced and properly gapped all 8 plugs
Replaced the PCV valve
Cleaned the MAF
Had it smoke tested and no leaks
Oil sending unit replaced

It runs fine and has absolutely no problem with gas mileage. Can ANYBODY tell me what i'm missing? My codes are P0171 and P0174 both showing- Powertrain System too lean Bank's 1 & 2.

 

[BANGEREXPO76]

Check the O2 sensors. Make sure they are functioning properly. If they are functioning then sometimes you have to take the throttle body off and the peice that the throttle body attaches to as well as the EGR valve and clean the gunk out of the EGR channels. Those codes are telling you the truck is not breathing well through the EGR system and the reason why usually is the system is clogged. Hope this helps. Good luck finding the issue.

Banger

 

[mille1cw]

Yeah the truck just hit 266,000 yesterday. I'll start cleaning the EGR and exhaust hoses. Thanks!

 

[MUSKYMAN52]

I'm running a thrush glasspack and it makes my o2 sensor think its lean but my mpg and hp increase about 20% (swear to God not kidding) did you do anything to your exhaust?

 

[expydaddy]

It sounds to me that your o2 sensors are working properly. I mean they are after all telling you something is too lean. When you replaced your pcv valve, did you replace the line that goes to the rear of the intake? That part has a tendency to develop a pin hole and collapse the boot attachment.

After a week of purchasing mine I got the dreaded po17something code of bank one being too lean. I searched on many a site and determined the pin hole thing was the culprit. i couldn't fit my sausage fingers back there to fix it. So I bought a scanner and would clear it for inspection time.

JDan has an amazing post on this. I found that my problem was a disconnected line on the drivers side that also plugs into a pcv type looking thing. It is kind of hidden under the factory black gauze looking wrap.

Good luck and keep looking!

 

[jbanks]

This could be a fuel delivery problem too. I had P0171(with no drive-ability problems)and replacing the fuel filter cured mine. But it could also be the pump or injectors. You might check the fuel pressure. I'm guessing my filter wasn't clogged enough to cause any problem at low RPM, but when more fuel was necessary it was restricted just enough to cause problems.

There is a whole checklist of things that can cause the lean codes. Someone posted the list from ford and it was quite a list. I think, vacuum leak, exhaust leak near 1st o2 sensors, fuel delivery, MAF, were near the top.

 

[mille1cw]

Alright, So i got fed up with my truck and actually broke down and took it to the stealership. I exhausted most of my resources and time (Va emissions inspection due in 2 days) so this seemed to be a last ditch effort. Well it turned out to be a successful visit, expensive, yet successful. When it was all said and done i dropped $1400 bones on getting the intake manifold/gasket and passenger side exhaust manifold gaskets replaced. There was a small leak from the gasket so this solved my problem. Add that to the generating list of potential problems that arise from those lean codes! Thanks for all of your help guys but at the end of the day my life got way to busy and had to take it in. And ain't nobody got time for that

 

[BANGEREXPO76]

Alright, So i got fed up with my truck and actually broke down and took it to the stealership. I exhausted most of my resources and time (Va emissions inspection due in 2 days) so this seemed to be a last ditch effort. Well it turned out to be a successful visit, expensive, yet successful. When it was all said and done i dropped $1400 bones on getting the intake manifold/gasket and passenger side exhaust manifold gaskets replaced. There was a small leak from the gasket so this solved my problem. Add that to the generating list of potential problems that arise from those lean codes! Thanks for all of your help guys but at the end of the day my life got way to busy and had to take it in. And ain't nobody got time for that

HIGHWAY ROBBERY.
But I understand the circumstances.