Ok guys took truck to shop got it back guy said nothing was wrong but something is sometime while driving on the hiway it seems to loss power and struggle on hills and other days it runs great any ideas?

 

Clean the egr. Test the map. Pull fuel pressure. Timing and tune up. Check the easy stuff first.

 

I've check fuel pressures it was good checked the regulator to just done a tune up plugs wires cap rotor pcv valve fuel filter and air filter checked egr vavle with vaccum pump it's working checked for vaccum leaks it was good I haven't checked the dphf for the egr I did replace the egr seloid cleaned maf sensor wonder if its the maf sensor going bad the only code that it reads is the rear o2 sensor behind the cat the check engine light is not on

 

Well fix the o2 and see what happens.

 

What exactly is the code. It can mean a few different things like an exhaust obstruction for example.

 

The code was po136 bank 1 sensor 2

 

What engine do you have. According to my list 136 should be the front sensor not switching, system lean. It appears to be a a fuel supply problem, but could be a dead cylinder or vacuum leak due to the limitations of the old diagnostic system. Test the O2 sensor. That's an easy test and will eliminate something. If you can check the fuel trim and MAF readings. Also test the coil and plugs for a good strong spark. Any incomplete detonation will result in a lean code. Also not switching means the truck never gets into closed loop so you are running on base timing, base fuel etc. I don't know how your mechanic said nothing was wrong with a code like that. It basically means everything is wrong.

 

It's the 5.8 it has the po136 witch said bank 1 sensor 2 and po141 truck runs great until it get warmed up and then it gets sluggish at hiway speed and on hills on the hiway but it's not all the time some times it runs good. My speedo bounces alittle around 55 so I don't use the cruise curse it goes crazy

 

I thought that sensor is the one behind the cat?

 

I'm getting 12.5mpg at the best!!