I have a 99 ext cab f150 with a 4.2 v-6 and a standard. The cel came on after I put in a bottle of fuel system cleaner. So I ran the truck out of gas and reset the computer. Which it came back on so I took it to Advance and their computer said that banks 1 and 2 were running lean. My first thought was fuel pump or clogged line. I just changed the fuel filter a couple of months ago. Im in the works of getting a fuel pressure gauge to check the pressure. It has sluggish accelleration but runs and drives great. Its always had sluggish accelleration though. My question is what could it be? And also what should the pressure be when I check it? Any help is greatly appreciated.

 

I had same condition on my 4.6l (lean codes) found a crack in pcv hose and cleaned the MAF. Codes have gone away

 

First i would check the pcv and maf because those dont cost anything to check. Then i would look into o2 sensors. My truck threw lean codes and i had to replace my front two o2 sensors. Cost about 85 dollars and about 45 minutes. If you can change a light bulb you can do this. Ford charges about 700 dollars for parts and labor. If it's not your pcv/maf then it's most likely your 02 sensors. Go to search feature and you can read all about them; plenty of threads on it.

 

I replaced 3 of 4 o2 sensors.... didnt know it had four until today. But CEL hasnt came back on. It has better accelleration. Thanks for the input.

 

Probably too late to help....the forward O2's are the ones that affect performance, and should be replaced at 30 - 40 k.... the back ones can wait until they go out.

 

Well it was going good until i let off the gas while cruising and the light came back on.... go figure. The maf and pcv are clean. Im going to take it back to Advance or call a friend that has the Snap On computer. Also there has been a ticking noise for about a year now and I thought it was exhaust but come to find out that its coming from inside the bellhousing. The clutch is hydraulic. There was a rubber boot I pulled out and was looking at the flywheel when it was running and it looked fine. Also what kinda flywheel and clutch does this year model utilize? Looks like a triple disc set up. I dunno its to new for me.

 

Also Ive been reading on here that some people getting those codes are for a pcv hose problem but the truck doesnt run radical at idle it only goes up and down a few times but thats because Ive reset the computer but when the truck is running I here air sucking from somewhere and when I pull the pcv and put my finger over the hole it runs the same. This was just a thought.

 

If it's sucking air from some other source then blocking the PCV won't make a difference.
Find the air sucking problem should find your fault. It's unmetered air that causes the trouble.
Even the dip stick has a seal around it's pipe seat, so it's all important.

 

I found a rubber elbow under the throttle body that went bad for the pcv and went to the ford house and got another so we will find out if the light comes back on.

 

I know some don't agree with this, but seeing as the rears are just heater circuits, you can buy on ebay an 02 simulator that will "simulate" the signal of a functioning rear sensor. Its cheaper and easy to do. They run like $25 plus shipping

 

Let me know what you find out I am having the same problem, I have changed the plugs, coil pack and fuel filter reset the computer and still have the cel on. Good luck to both of us I guess.

 

98, are you saying the rear ox sensors are just heaters?
They report their switching signals to the PCM as part of a calculation done to evaluate the operation of the convertors.
This is done by comparing switch rates for the front sensors to the rears after the exhaust has passed thru. A record is stored in PCM with a reference table to tell when the cats fall below performance, lighting the CEL lamp.
Also the Ox sensors detect raw fuel should cylinders missfire and pass fuel thru that could overheat the cats and ruin them. This shows as a blinking CEL lamp.
Maybe I missunderstand what you are referring to. If so disreguard the above but, it's how the system works.
Just eliminating things brings on more change than is realized.

 

For a week now the light has been off thanks to a $10 part at the Ford parts house. Looking through here and looking over the engine I found a rubber elbow that goes to the pcv. The elbow Im preferring to is right under the throttle body and you can barely touch it with a finger. Wish I would have known this sooner before the O2 sensors. Thanks yall.

 

man at least take one of the 02 sensors back ( the rear one) Waste of money unless it was broke. If it aint broke dont fix it! But if you do have alot of miles on your ride the front two could have used a changing. It helps w/ mpg. Good job finding the problem though. Took me 6 months and 500 bucks to find the problem on my old 01 w/ only 55K miles on it at the time. Crazy huh?

 

hey oldgrey, I am in the same mess right now. You say changing the elbow connected to the pcv was the problem? Was it hard to change? I have already done the o2 sensors, plugs, fuel filter, mas clean, others have suggested a vacum leak and thats what I am left thinking. What are your thoughts-and how did you know the elbow was bad, a crack or sucking noise? Thanks