A bit stumped
Thread Starter
|
New User
Joined: Sep 2011
Posts: 1
Likes: 0
A bit stumped
I have a 2003 F150 Supercrew with a 4.6 SOHC. I started having a rough idle and it would quit when stopped. It initially threw a code P0171 and P0174. I have replaced IAC and cleaned (multiple times) the MAF. Then found that the tube leading from the PCV to the back of the Manifold Intake had a big hole. So I replaced the tube thinking wah lah it should be fixed. Not so fast. Now the truck runs fine until it warms up then it seems like it can't get out of its own way. The funny thing is that it idles just fine. Its when I put it in gear and try to take off that it seems misfire and almost acts like it is drowning. More info ... In the midst of the first codes it threw it added 2 more codes P1131 and P1151 while I was monitoring it. I have a meter to monitor all the fun stuff and I am watching the 02S11 voltage bounce around quite a bit. the 02S21 not so much. Also this just in, it has a pending code of P0171 again and new code P0303. Any thoughts?
Hotshot
Joined: Jul 2005
Posts: 11,931
Likes: 180
171 and 174 normally mean you have a bad intake leak. This is normally the small vacuum hoses getting old, hard, and cracked. Could be intake manifold, but less common... the 303 code means the #3 cylinder is misfire.. that should be the third coil back on the passenger side. Most common misfire is bad COP.
Lead Driver
Joined: Sep 2006
Posts: 7,907
Likes: 143
Your stumped because you don't know what the codes are telling you.
All the codes except the 303 are telling you the OX sensors are seeing an issue with the motor.
They are not the problems themselves.
The code 303 is a hard fault with cylinder 3.
This is likely causing much of the codes you see along with any intake air leaks.
Service the 303 code first or you can't get anywhere with the other causes because that cylinder may be pumping raw gas into the cats if it is an ignition fault or just excess air if the injector is not working.
Looking at the OX sensor switching; it's normal the see the upstream values moveing (switching) under normal conditions.
The rear sensors will be slow because they are only monitoring the OX stored in the rear cats and do not do any fuel control like the fronts do.
Good luck.
All the codes except the 303 are telling you the OX sensors are seeing an issue with the motor.
They are not the problems themselves.
The code 303 is a hard fault with cylinder 3.
This is likely causing much of the codes you see along with any intake air leaks.
Service the 303 code first or you can't get anywhere with the other causes because that cylinder may be pumping raw gas into the cats if it is an ignition fault or just excess air if the injector is not working.
Looking at the OX sensor switching; it's normal the see the upstream values moveing (switching) under normal conditions.
The rear sensors will be slow because they are only monitoring the OX stored in the rear cats and do not do any fuel control like the fronts do.
Good luck.
Thread
Thread Starter
Forum
Replies
Last Post
