Oh and also how can I find out if it needs reflash?? And If i have to take it there what are the recomendations the EDGE chip do I leave it in or pull it all out so they never know I had it. Will they make note on the warranty account if they think I have one?? And can they tell I had a chip even whenI uninstall it?? Thanks A million.

 

I have about 69K and my last trip I got just over 21mpg. Key to good mileage is driving less than 70mph and easy on the starts and stops.

 

kertoncol.

You have a 2003 and the complaint is with the 2004.5. Your year usually does great mileage. Many 2004.5's suck - - literally.

 

Good point. I didn't notice that.

 

I need to fill up tomorrow, I refused to fill up today, I need five more miles to crack the 400 mile mark on the tank.... 230 miles of which was cruise controlled to just under 2k rpm so we will see what it gets me. this was with half a bottle of ps white bottle. I am most likely going to dump a whole bottle in this tank and see if I notice anything great.

 

i have the same problem....14.5 around town barely cracked 16mpg's at 2k rpm too.....its been in to reflash...powerpup is updated...but it also got terrible mileage in the beginning...told me to wait til 15k i am now at 28k and nothing better

 

Yep there is a big difference between 04.5s for some reason.

Mine has been gettting around 18 mpg with mixed driving and pulling a 8000 lbs trailer 50 miles. And that's one winter grade. The fuel does make at least 1 mpg diff. I am thinking more like 2 mpg diff! All in all I am very happy with my mileage so far. I hope it keeps it up!

 

How does one check the over pressure valve?
That is the valve comming off the top of the rail with a return line on it right?

 

I have over 38,000 on mine and the lowest mileage I ever got unloaded we between 17-18 traveling on the highway at 70+mph. The highest I've gotten was 24.4 unloaded on the highway 60+mph during the summer. I've hand calculated every tank since it was new and winter runs between 19-20 and summer between 21-22. I've had 2 trucks and both got about the same mileage. The first one was stolen in Montreal with only 10,000 miles on it. I'm not sure why some 04.5's get good mileage and some don't, but I can say I love mine. I believe something is wrong with the ones that don't but I also know that it has a lot to do with the way you drive too.

 

> How does one check the over pressure valve?

either get a scan tool on the engine and take it for a drive, comparing desired rail pressure with actual rail pressure OR

put a piece of hose on the return line and see if any fuel is coming off it while you are driving.

>That is the valve comming off the top of the rail with a return line on it right?

Yep.

 

I did a 300 mile trip last weekend, 60-65 MPH, and got 20.5 MPG. That includes a bit of stop and go, lots of hills, and up to the ski area at 9,000 feet. I'm happy with that. Truck is stock. I agree that these trucks like to be worked. Over the holidays we did a 2,000 mile trip with the slide-in camper (1700 lbs. loaded), worked it hard, and got a little over 15 MPG for the trip (70-75 MPH). After hauling the camper, the truck is really running well.

 

You can disconnect the line from the valve going to the fuel filter housing. If you have any fuel flow at all, the valve is probably bad.

You should have no flow from that valve. If it is open, you will be limited to somewhere around 70MPa. Its supposed to be like a switch. Its either fully open or fully closed. If its leaking, its bad.

I bet most (90%) of the problems with fuel economy on 325/610 engines are related to manufacturing tolerences associated with the injectors that affect the pilot quantity that is actually being injected.

 

"I bet most (90%) of the problems with fuel economy on 325/610 engines are related to manufacturing tolerences associated with the injectors that affect the pilot quantity that is actually being injected."

Amen, brother ! No pilot shot and you just lost about 2 degrees of timing. I am not getting into this except to say I agree. BigBlock: its your baby.

 

well it paid off, keeping it below 2k rpm netted me a whopper, 14 mpg....... momma dawgs that bites, I'm goin back to driveng it like I stole it, more fun and humph, only a half mpg difference..... warm weather will find me layin under the truck doing the tone ring mod. MPG was hand calculated, overhead guessed 17 mpg, quad box on 100 hp setting.. wonder if a tank at 140 setting would be better?

 

Something is wrong if you are hand calculating 14 and the overhead is saying 17. Do you reset the overhead when you fill up?

I agree that you should drive it like you stole it. There really isn't any other way.