Lately my 04 6.0 PSD has been running crappy at startup and getting about 10 mpg. I started using diesel kleen and I took it to the dealer and had them replace the fuel filters. They found a bad injector and a bad sensor (SES I think). Both were fixed and no change, still rough start up and only 10 or 11 mpg. I requested the catch code be updated to FSM7. The mechanic said that after the sensor and injector were fixed they updated the code to the newest one(they couldn't tell me which one), and that after they update it they cannot use an older code. I would just like to know if there is a simple solution to these issues?

 

Perhaps a clogged/dirty EGR valve. I'd remove it and inspect and clean with brake cleaner if neccessary.

 

Could it be that simple? The truck got 16-18 mpg before the engine light came on and they replaced that sensor and injector. Would it help to disconnect the egr valve, or is it better to leave pluged in?

 

Personally I would loose the EGR as all it does is introduce soot into the engine. I would also block the EGR cooler as all your doing is adding extra heat to the coolant causing boilover in alot of cases leading to coolant loss out the degas bottle.

You can attempt to unplug the EGR, you'll want to do this while the engine is off. The check engine light may or may not come on. I personally tried this in my 05 excursion with a 04 motor, worked fine for about 50 miles then it came on and computer went into limp mode, running crappy. So I had to plug it back in. Though I never did mess with the throttle plate, maybe that had something to do with it. They say all California vehicles will throw the light immediately I believe. All I can say is you can try, some have luck others dont.

It could possibly be that easy just cleaning it. Doesn't take much to remove the valve, I think its two bolts and a matter of unplugging the harness. How many miles do you have on your rig now? Excessive idling does not help with the EGR fouling up. They say adding fuel additive such as Powerservice the full bottle will help with the EGR equipped engines.

I personally haven't had a issue at this time with 31k, I currently run the SCMT on Towsafe, I never see any smoke coming out my exhaust - when I tried on economy I noticed it'll throw the black smoke out alot. My conclusion is the SCMT must be helping me out there with the tuning.

As far as the flashing of the computer, well that could be good or it could be bad. I'm still on my original programming back from Sep-04. Others report after getting the flash it's made it worse fuel economy wise, some say their truck warms up quicker, but all say it definately makes the tow/haul less agressive with the engine braking. Once you get it flashed, you can never go back.

 

Thanks for the reply. I will disconnect the egr valve and see what happens tomorrow morning. The truck has 70,000 miles on it, and the build date was 9-03. And this all started about 3-4000 miles ago. I was also wondering about the sensor they replaced, if it were faulty would it cause this fuel mileage issue? I also read a post where someone had a bad injector and the mechanic recommended a new fuel pump? I would like the truck to go back the the way it was, this 10 mpg crap is not to much fun at the pump.