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Early 99 Turbo/Waste Gate Problem
I am new to this site and hope someone can give me a little help or maybe they have experienced the same thing.
I have an early 99 F-350 Crew Cab, 7.3L, 6 spd manual transmission. I have an Edge Tuner installed. The things I will describe happen on all 5 settings and in “Stock” mode. Two things are happening that I am a little uncertain about.
1- At a low throttle, in 2nd or 3rd gear, around town I hear a hissing sound from the Turbo and then I look at the boost gauge, it will go from approximately 2.2 psi to 0 psi. As soon as I get back on the throttle the boost will jump back to 2.2 or a little higher depending on how much I get on the throttle. If the boost gauge is at 0 psi and I add throttle very slowly I can keep the boost at 0 psi all the way to 2000 rpm.
2- If I have the pickup on cruise at approximately 65-70 mph, with no load, and the boost gauge reads 6.0 psi it will drop to approximately 5.3 psi -5.5 psi and then go to 6.2 psi -6.3 psi and then settle back to 6.0 psi and start all over again. When the pickup is doing this you can feel it surging. If it stays above or below 6.0 psi it seems to work just fine. If I am pulling my 32 foot fifth wheel the pickup acts like there is no problem at all. If I have it on cruise with the fifth wheel it will range form 8.0 psi to 12.0 psi on the boost, depending on wind, grade of the road, ect. No problems at all, no surging.
Fuel mileage is 14 mpg -18 mpg depending on how I drive while empty. Fuel mileage while pulling the fifth wheel is 10.0 mpg – 12.0 mpg. I took the vehicle to a local mechanic and he said it was a sensor that cost $186 plus labor. He also added that this may not be the problem and this was the place to start. I have not changed the sensor yet, was looking for some input from you guys first.
Thanks in advance for all your help.