Question Strange Subtle Symptoms - Advice?

[jascott]

2008 Job 3 F250 w/ 42k on the truck. I have run the Spartan 210 tune for the last 35k and have recently noticed a change in the way the truck runs. Looking for advice as I have a 4000 mile trip planned for July 1 towing a 12k 5th Wheel.

Problem: Trucks seems just a bit down on power, requires more throttle to do the same things as it used to. MPG seems to be down just a bit (maybe 1 - 2 mpg) "Exhaust Leak" type noise when truck is under load and above 1900 rpm. I've been all under the truck and can't find anything that looks like an exhaust leak. I have switched to the 150 Spartan tune to test, and the noise is less pronounced, but still there.

Before these problems started I installed new Michelin LTX AT2 tires (stock size) and installed an aux in bed fuel tank. The aux fuel tank and the factory tank run through a switching valve that switches the supply/return lines along with the sending wires to the fuel gauge. The problem happens regardless of what tank I am on. The aux tank is using 3/8" hose for the supply line.

Do you think the new tires are causing the performance/mpg changes? They are factory size and not all that aggressive.

Any chance the fuel switch valve is not supplying enough volume of fuel? According to the DashDaq, I don't have any codes.

Does any of this sound like an EGR issue?

I'm considering returning the truck completely to stock and taking it to the dealer. I just don't want to end up stranded on my trip... Wife and kids will not be happy at all...

[jascott]

Truck goes to dealer on Tuesday...

[BlueF350]

When did you last change your fuel filters? My truck was dogging it until I changed the fuel filter(s).

[superdutydixie]

let us know what they find, good luck. hopefully it's nothing serious

[kcschultz]

The added weight of the extra fuel tank may account for the loss in mpg. Is there a pump on the extra tank somewhere? That could be the source of your sounds.

[M90Ranger]

I would go after the exhaust sound first.
The RH turbo inlet pipe on these are know to leak at the flex joint.
You'll have a lack of power and usually no codes.
Look for soot on the foil insulation on the firewall.

[caliber]

The exhaust noise might not be exhaust,it could be boost pressure, look at charge air tubes and cooler.Check all the clamps, one could be broke or loose. A hole in one of the couplers or cracked cooler will give less power and less fuel mileage.

[jascott]

I can't find evidence of any leaks, loose boots, etc. I did detune the truck to stock no regen and don't notice the noise now at all. My guess is the EGR valve was sticking from running the 210 tune all the time. Running the other tune a bit has freed up the valve.

I'd like the dealer to replace the EGR with the new version, but we'll see if they will under warranty. I've also got a few other things for them to look at...

I'll update after I get it back. Thanks for all the help.

[jascott]

I drove it some with the stock/no regen tune and things seemed to get better. I do have an original design EGR and the dealer is replacing it because the symptoms match and EGR issue. Hopefully this will take care of it. Guess I'll start running the 150 tune from here on out.

[jascott]

I've been all over this again. I don't see any evidence of soot anywhere. I've also checked all the rubber boots. I can hit 40psi also, so I'm not sure what that means.

I have noticed my EGTs seem higher than normal, but I bet that is because of running the stockNR tune and the EGR being on. The DD Says 700-800 at a 70mph cruise on flat ground. It will hit 1000 easy just merging onto the hwy.

The truck should go back in next week and I am supposed to drive with the tech. I've got a 4000 mile 5th wheel vacation planned soon and I want the truck to be at 100%.

Originally Posted by M90Ranger

I would go after the exhaust sound first.
The RH turbo inlet pipe on these are know to leak at the flex joint.
You'll have a lack of power and usually no codes.
Look for soot on the foil insulation on the firewall.