new injectors and fuel filter, still runs lean.

[sophiejoey]

Hey there, I just replaced the fuel filter last month after i got the P0171 and P0174 codes, both banks running lean. After a week I got both codes again so I replaced the 11 year old injectors. Another week later I got the same codes, and its getting worse. It's got 16Hg of vacuum which is way too low. Scoured the engine for vacuum leaks but cant find any. I looked all over the internet for answers but can't find any info to this. It's a 2000 5.4L Xlt 3/4T. Also its got all new coils, plugs, and wires, but doubt that would make a difference. Any info would be greatly appreciated! Thanks ahead of time.

 

[rburch]

You should check and clean the MAF. 90% of the time if you are getting lean conditions on both banks it is caused by a faulty or broken MAF.

After cleaning if it doesnt improve your problem you should try another MAF.

 

[sophiejoey]

ok, I did clean it but I didn't try replacing it, but they're rather spendy. Is there any way to check if it's working right nor not?

 

[rburch]

http://www.youtube.com/watch?v=goxRsNtY8DM

http://www.youtube.com/watch?v=JulcFtjirqs&feature=relmfu

 

[Walk03XLT]

+1 for this info. Not something I need for now but great to have for the future. Thanks Rburch

 

[Thermo]

sophiejoey, check something for me really quick. Look on the passenger side valve cover. You will find the PCV valve there. Follow that line back to the center of the engine and find where it taps into the intake. Is that rubber boot there in good condition or is it cracked and whatnot? I am better you have a cracked boot and that is causing your issues.

 

[rburch]

Thermo, That is the first thing that i thought of when i first seen the post but he says that he has been all over the engine for vacuum leaks. And if he searched for solutions like he says, that would have popped up everywhere!

 

[2000eb]

number one cause of runnin lean tho just did one today on someone elses expy their truck runs great now

 

[rburch]

Yeah i know. Second is COP. But like i said i think they would have found that one on their own.

Update Sophiejoey?

 

[sophiejoey]

hey again, sorry it took so long to get back, I was busy up north and in Fargo, i'm officially government property of the U.S. Air Force now! But I did the 2 tests from the videos and it confirmed the MAF sensor was bad, picked one up at O'Rielly's and it runs great now. Had trouble with the boot under neath it where the rubber boot plugs the hole the wires go through, got another 2 Hg of vacuum from fixing that but still ran horrible until I replaced the MAF. Gotta give ya thanks though guys I never expected this much info and so fast, you guys really know your stuff! Ya saved me hours of wasted time and money. Thanks!

 

[rburch]

Your Welcome!