guys I cant shake this check engine light, the OB2 codes read too lean on both banks. I have tried injector cleaner and resetting the codes, im going to change the fuel filter next (never been changed) after that im stumped ... any ideas?

98 v8 4.6 4x4, keep in mind I am a mechanical infant so you will have to explain it like im a 3 year old.

 

I had the same codes and it was the O2 sensors. Are you getting bad mpg? If so, most likely this. They are real easy and cheap. Find a Haynes manual and it describes it really well. How many miles on your truck? Probably wouldnt hurt to change fuel filter and maybe clean throttle body

Keep us updated. Good luck.

 

64k o2 you think so? not the right ob2 code for o2 though

 

What are the codes? p: I'm about 75% sure I changed mine and it fixed the CEL. I would change one o2 and see if it's the fix. If not, put it in the other one. If still doesnt take it back and try something else. Any vaccum leaks? PCV? MAF? Try this thread here. The O2 fixed my problem and others. GOod luck and let me know how it goes. I have about 58k on mine and the o2's went out about 51k

 

Sorry forgot thread here you go:

http://www.f150online.com/forums/sho...ighlight=p0171

 

ok ill replace that too, the ironic part of that post is all the AZ bashing ,and I just started as a GM for AZ, but hey they didnt hire me to be a mechanic they highered me to run a store, I have 5 ASE guys on staff, but I trust the forum more.

 

I actually like AZ. Free codes! Had no problems out of them. Bosch parts seem to be the most of the bashing. Most of the bashing has a lot to do with Bosch plugs but I personally have no problem out of Bosch except for one of the O2 sensors that I bought was defective, which they replaced (1 year warranty). Maybe before buying the o2's, clean what you can clean. MAF, Throttle body, egr ports. I got a lot better performance after i cleaned TB and ports. I replaced my fuel filter and cleaned EGR today just for kicks. FF is real easy (5 minutes) but have to have special tool($5). I didnt relieve the fuel pressure. Just open gas cap and let sit for about 5 minutes and go at it. Let me know how it works out for ya.

 

how do i clean the throttle body?

 

First take off the intake. The intake leads to the throttle body. Then take off the IAC valve and hoses on the TB. After that there are 4 bolts that hold the entire TB plenum on. Take those 4 off. Then if you look on the back right of it the EGR has to be removed from the TB plenum. You can remove the EGR also but a Pain. Anyway there are two screws that you have to unscrew from EGR leading to plenum. After that the plenum should be able to lift straight off. Take at the gaskets you have (TB gasket, IAC gasket, and EGR gasket.) i didnt have to replace mine. NExt take about 2 cans of Carb cleaner, 100 q tips, a toothbrush, and a wire brush if you have one. Some people have to drill the carbon b/u out, but w/ 60K miles you shouldnt have to. Then clean all the carbon out of all the holes in the plenum and then replace.

Found a perfect site that shows pics and process. Hope this helps
http://www.fordf150.net/howto/throttlebodyclean.php

Take a look at the MAF, PCV. May just need some cleaning or 3 dollar pcv. VACCUM LEAKS are a big problem. Look on the very back of TB and there is a Hose going back there that may have a hairline crack that could easily cause this

 

Breaker,
I had the exact two same codes for lean on bank 1&2 and o2 meter slow response also. Just yesterday I had my fuel filter replaced and my codes reset. The filter was completely plugged. My mechanic says it was the filter giving the lean codes and the o2's weren't acting correctly because of the lean problem. Today with around 60 miles since filter replacement everything appears to be ok. I suggest that you replace the filter.
He also replaced a piece to the very troublesome vacuum tubing that has given many persons on these boards trouble. Its the vacuum header off the top of the PCV valve on the passanger side of the truck. The particular piece that was suspected bad on my truck was a straight piece that connected to the intake area. This tube connects in several different places and if you squeeze the rubber connectors you will find that they are rotten or very gummy feeling. If they are you will need to replace the header. I think they are around $25 at the dealership.

 

My wife's Exp. and my 150 had the same problem and they both were the PVC rubber elbow. Both had a hole in them at the bend.

 

Well I guess I will try the 6 buck solution and replace the fuel filter before i replace the O2's at 50 a pop and since both banks read lean ill have to replace both. Then Ill go from there.

 

I have replaced my downstream O2 sensor with a Bosch and the check engine light came on with the same code. A ford mechanic told me the wiring could have a short in it. Could it be more likely a faulty sensor straight out of the box?

 

Yup, this is a VERY common cause of PO171/174. My CEL came on a few weeks ago (@ 125,000 miles), and sure enough, the PCV hose had a hole back by the engine, and another arm of the hose was collapsed and restricting airflow. Easy fix: the part costs about $40, and takes maybe 10 minutes.

I saw a post from a Ford Mechanic where he said this is the first thing he suspects when he sees PO171/174 (both banks running lean): he's replaced 100's of these hose assemblies...

Chris