I have a 03 7.3 4x4 crew cab. 125000 miles, Superchip Programmer & Airraid Intake kit. I run BF Goodrich AT 33x12.50x16.5 Tires With A Leveling Kit in Front End. I recently switched over to Synthetic Oil (Mobil 1 Delvac I think). Since the switch, I seem to have lost fuel mileage. I am only getting 13.5-14 mpg. This is mostly highway driving...cruise control on 80. That puts my RPM around 2150. I know many if you are going to say that is all I shold get, however I used to get 16-17 driving the same way. I also did switch out to the "blue" cps around a year ago. I did not see any significant change with the cps change (other than my truck started runing again). I live in south florida, so I do not think "winter blend" would be a factor. I changed my fuel filter at the same time as I changed the oil. I do not have any fluid leaks (oil or fuel). Tire pressure is up to snuff...Any Ideas???

2nd Question....

I am looking to upgrade my exhaust. I think I am going to go with a turbo back 4" system. I do not want the "over the top" sound of a straight pipe....
however I would like to let the engine breath easier. I have read about the changes in the tourque curve. Will this adversly affect my towing ability??? I tow a swamp buggy during hunting season, and boats in the summer. A good frien of mine just unhooked he exhaust right before the muffler, and claimed to gain almost 2 miles to the gallon. Does that even seem possible???

Thanks in advance for any and all help. This is by far the best place I have found for information!!!

Joe

 

welcome to FTE,
1. if you changed to synthetic and lost so much, change it back to dino and see if you get your milage back on track ,other than that if everything is up to par, you should not see drop like that
2. did he drop the muffler off? or he left it in ?
if he did you will gain a little, milage, you just removed the biggest restriction in you exhaust system, if you want to save money just remove muffler and put the piece of pipe there,

 

yes... WELCOME to FTE!!!

16-17 mpg is also consistent with the mileage I get when I'm running highway at the 80mph range. I've never heard of anyone losing mileage with a synthetic oil. I personally have seen increases in mpg every time I've switched an engine to synthetics.

Couple of questions for you....
1) Did you increase the oil weight with this change? That may have some impact.
2) Also, have you checked all your boots to see if something may have been knocked loose when you were doing the other work under the hood? This, too can affect mpg performance.

Regarding the muffler issue, you can look for the Walker Big Truck muffler as a moderated point between straight pipes and the stock muffler you have. http://www.blackclouddiesel.com/Ford/walkermuffler.htm

 

To my knowledge the oil is the same weight... I have checked the clamps on my boots. They all seem to be tight. I have not "pressure tested" them. I was doing some additional reading and saw people talking about EBPV tubing?? what is this, and how would it get clogged. I have never cleaned this out....does it make a big difference

 

also... what is the latest thinking on the blue cps

 

i've heard mixed results on the blue CPS, and there is another thread running right now where Ford has just released a "new" and "improved" CPS that is only $25. I ordered one from these folks, and it is $25 plus a few pennies, delivered to my door. http://fordparts.com/cart/?pn=F7TZ-1...&submit=Search

The CPS thread link is https://www.ford-trucks.com/forums/6...may-1st-2.html

The EBPV is the exhaust back pressure valve... but that hits the limit of my understanding. I'm sure that someone will chime in about how to clean it and whether or not that could be related.

 

The EBP (Exhaust Back Pressure) tubing runs from the EBP sensor to the passenger side exhaust manifold. It and the sensor is used to control the EBP valve to help warm the engine on cold days. Some say that it does improve your mileage some if the tube is clean and the sensor is working right. I don't think you would notice that much differance from that. I just recently had mine cleaned an the sensor replaced. I have not noticed any increase in my mileage. I have noticed a drop in my fuel mileage since I have had to start using the ULSD. I don't know if that is the whole reason for my decrease, but do feel like that has something to do with it. I also use DK additive in each tank and that may have something to do with it also. Mostly I think it is my heavy foot. Now that it has started warming up, I have my windows down more and the strait pipe exhaust turned up. I also haven't driven far without my boat hooked behind me.

 

does anyone know why people stopped using the blue cps???

ULSD ??? Ultra low sulfar diesel??

 

YES..... ULSD = ultra low sulfur diesel

Blue vs Black = more money. The new one is gray, from what I hear, and is less money.

 

Use your tuner to check for any DTC's. The exhaust backpressure system will set a "soft" code (meaning will not turn on the check engine light). If you a P0470 or P0478 that will mean you have a plugged tube/sensor or a bad sensor itself. Just a thought though, I know with my truck running 35" tires I am turning 2100 to 2200 at 80 mph. It sounds like your speedometer is not calibrated properly or if you have a catalytic convertor it may be plugged. (only very few trucks came with cat's) I really don't think the synthetic is the cause of your problem.

 

No catalytic converter... No codes...

I have a new black cps. Should I try changing back and see what happens?

 

If you happen to have an extra it won't hurt for the 10 minutes it takes to switch it out. I don't think that is your issue though. How many miles have you put on your truck since your oil change? Also my be something to do with the ULSD. Maybe try using to additive over the next few tanks and see if it rises. I use DieselKleen and love it. As for the exhaust system. If you don't want much louder than stock go with a good system like MBRP. It has a nice sound and isn't much louder than stock.

 

oil change 5000 miles ago. time to change again, and that's why the questions. Is it worth the extra $ to use synthetic? I use dk on every 4th or 5th tank. Engine sounds quieter with the dk, however no additional fuel mileage.

Jake, what mileage do you get on your truck? similar tires...intake..programer.
what is a 203*t-stat, and what does it do

 

203° thermostat allows the engine to run hotter than the OEM design, which is apparently cooler than optimal for a diesel. The higher temp stat allows the engine to run closer to optimium for diesel combustion.

 

I get about 13 to 14 mpg around town and I get 17 to 19 on the highway depending on how fast I drive. I have gotten 19.2 twice but that was driving at 62 mph with the cruise set. The 203 degree t-stat is to help the diesel burn better. These trucks have a t-stat that is too cold and can't get the oil temp to the most effecitive temp (220-230 degrees) because oil temp is usually 10 to 20 degrees over coolant temp. Personally I don't know if the t-stat has helped my mileage much because up here in Washington we just switched back to summer blend of fuel and I installed the t-stat in Feburary. It does help my truck warm up faster though.

As far as the oil change goes, I would give it one more shot. You are due for an oil change and I would give it another chance. I know synthetics clean engines better than regular dino oil. Maybe it had time to clean up some deposits that dino oil left behind?? Just a thought. I picked up about 1/2 to the gallon running Royal Purple. I know my fuel mileage dropped a bit when the switch to USLD, so I now run the DK additive every tank.