hi guys I working on a 98 f250 with the 5.4 vin code L 180,000 miles, It idles rough and is short on power. I tried to pass a truck on the interstate today and It wouldn't do it.
I put a fuel filter in it and that made it drivable again. then I did plugs and o2 sensors, I couldn't get the one on the passenger side at the manifold, but changed the other 3. The only code it's showing is "bank two o2 sensor 1 blank signal" I can't see a mass air flow sensor on it and I've heard there's a way to reset the timing, but don't know how

 

do you have a scan tool or lab scope access. as far as the 02 sensor goes you need to see what is reaction is when hot how does the truck run cold. it would help to look at your fuel trim. when this happened was after fuel up. why do ask about the timing. the MAF should be in your air cleaner. some of those sensors are not the same as the other you have down and upstream sensors. check fuel pressure yet.

 

fuel pressure is 35 at an idle, un hook the regulator and it will go up to 40. As with the timing sometimes with these computer motors you just need to reset them, I had the battery unhooked overnight, but I don't know if that reset it or not. I'll look again but the only sensor I see is a single wire air intake sensor. I think my scan tool will monitor the fuel trim,

 

Just suffering from the same issue.. Check your fuel pressure.. I've changed MAF to o2 sensors, working off vacuum readings and engine codes.. lol..

Under load I've having a faint sputter, and loss of power.. Just a thought..

 

I need a different gauge to check it going down the road, I leaning towards a weak coil pack, but I check the pressure again, I don't think it was idling very rough when I checked it before.

 

do you have a spark tester. check your system voltage when its running bad. try to find out what cylinders are misfiring if any . does this truck have cats in it still tried feeling the pressure out the tail pipe. what type of scan tool are you using.

 

actron is my tool I've worked on v10s and it will show the mis fire codes

 

I figured it out, I had a broken vacuum boot on the back of the intake.