K, I think I may have purchased someone else's frustration. 2008 6.4l with 270,000 km. Truck seems meticulously maintained in the King Ranch trim. Did a mileage/hour calculation and the truck has averaged about 40mph through it's life (55km/h). Personally I have owned many diesel powered devices including 2 7.3 Powerstroke diesels. My issue is that this truck does not have the performance or fuel mileage I would expect (not even close). I suspect the previous owner was trying to resolve a problem through recommendations. First suspect (in my opinion) was exhaust pack pressure sensor. Next may have been a suspected exhaust system issue. Who knows what else. The previous owner installed a straight through (no muffler) exhaust, did the delete stuff and installed a Spartan tuner. He also (after I suspect was told to) re-routed the Exhaust Back Pressure tube to behind the engine near the top.
Here are the things (that I can remember) that I have found. At first, I thought it was the exhaust back pressure valve since it was generating a P0472 code. Seemed to fit the symptoms. I then discovered that the Spartan tuner could be 'opened up' for other sensor readings and could read the exhaust pressure in real time. The reading has been all over the board. At first I began to think I had a bad connection in the wiring. I just completed a 1200 km (750 mi) trip and watched the gauges quite carefully. The first half, I had the Spartan tuner set at 210 hp tow mode. The exhaust back pressure would bounce around in the 30 psi range most of the time, then would occasionally drop to zero. When the back pressure was indicating, the turbo boost would be above 20 psi (cruising at 70 mph). When the back pressure dropped off to nothing, the boost would drop, but the truck actually seemed to 'open up' and drive more freely (if that makes sense).
On the return part of my trip, I tuned the truck for the 40hp setting. Thought it should improve my mileage. Once again, set the cruise at 70 mph (Actually 113 km/h on the GPS). The back pressure reading never dropped to 0, but quite often was reading 50psi. As for turbo boost, it was always over 20 and more in the 30psi range. The whole time, I could hear the turbo whine. As for power, my 7.3 intercooled has more. When I arrived home, I fueled up and it worked out to an astounding 14 mpg for a US based gallon.
Here are my thoughts and I will let you experts tear me to shreds or give me more insight to what I suspect. I think there is a sensor/mechanical linkage that controls bypass (like a wastegate) that is malfunctioning. I can't imagine how many sensors there are on here, but I feel it might even be more than one that is an issue. I suspect that the Spartan tuner ignores some of the sensors on the higher hp settings and that is why it gives more 'real' power on the higher settings. I did briefly put it on the 310 hp and the 350 hp settings and it was completely scary (for a 1 ton lol). I just really didn't care for the coal coming out of the pipes. As for mileage, on the first half of the trip on the 210 hp setting, it was actually better.
Hope someone can help, or at least explain how all the systems/sensors function in this powertrain.
Thanks in advance.
Here are the things (that I can remember) that I have found. At first, I thought it was the exhaust back pressure valve since it was generating a P0472 code. Seemed to fit the symptoms. I then discovered that the Spartan tuner could be 'opened up' for other sensor readings and could read the exhaust pressure in real time. The reading has been all over the board. At first I began to think I had a bad connection in the wiring. I just completed a 1200 km (750 mi) trip and watched the gauges quite carefully. The first half, I had the Spartan tuner set at 210 hp tow mode. The exhaust back pressure would bounce around in the 30 psi range most of the time, then would occasionally drop to zero. When the back pressure was indicating, the turbo boost would be above 20 psi (cruising at 70 mph). When the back pressure dropped off to nothing, the boost would drop, but the truck actually seemed to 'open up' and drive more freely (if that makes sense).
On the return part of my trip, I tuned the truck for the 40hp setting. Thought it should improve my mileage. Once again, set the cruise at 70 mph (Actually 113 km/h on the GPS). The back pressure reading never dropped to 0, but quite often was reading 50psi. As for turbo boost, it was always over 20 and more in the 30psi range. The whole time, I could hear the turbo whine. As for power, my 7.3 intercooled has more. When I arrived home, I fueled up and it worked out to an astounding 14 mpg for a US based gallon.
Here are my thoughts and I will let you experts tear me to shreds or give me more insight to what I suspect. I think there is a sensor/mechanical linkage that controls bypass (like a wastegate) that is malfunctioning. I can't imagine how many sensors there are on here, but I feel it might even be more than one that is an issue. I suspect that the Spartan tuner ignores some of the sensors on the higher hp settings and that is why it gives more 'real' power on the higher settings. I did briefly put it on the 310 hp and the 350 hp settings and it was completely scary (for a 1 ton lol). I just really didn't care for the coal coming out of the pipes. As for mileage, on the first half of the trip on the 210 hp setting, it was actually better.
Hope someone can help, or at least explain how all the systems/sensors function in this powertrain.
Thanks in advance.
