To start off with, I am driving a 1996 f150 5.0L. I am posting in this section because it is running the OBDII system.

I have a check engine light with four codes coming up, p0155, p0135, p0141 and p0171. I think its funny how all three of my oxygen sensors take a **** at the same time. I ohmed two of them out and one was 3.7 and the other was 3.9. i read on autozones website that they are supposed to be "around" 6 ohms. I also own a ford van that is also OBDII so I took one of the sensors off and ohmed that. I got 4.0 ohms. They are almost the same so i dont think its the sensors themselves that are bad. i went through and cleaned out all the grounds and checked all the vacuum lines I could find. I am thinking its and electrical issue. What does everyone else think it could be? It also runs rough at idle but smooths out as the RPMs increase.

 

Look for a vacuum leak...Check fuel pressure...When is the last time the fuel filter and air filter was changed?

 

fuel filter was like six months ago. i have not touched the airfilter but ive also read it could be a dirty MAF sensor

 

Cleaning the MAF is a good start...The P0171 is a lean code and might be caused by a dirty MAF or low fuel pressure...but that is only for bank one side...You didn't have a P0174 did you?

 

no it was only the 171 and I was gonna try and find a fuel pressure tester