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Discussion Starter #1
Since there is a ton of respected Diesel people here. I need to ask a question on a on going problem. A 97 f350 7.3 power stroke is in bad shape. This thing has NO POWER 90% of the time.
When cold it's undrivable. top speed about35 mph. After it's warmed up it falls on it's face at higher rpm. It has a hard time at 50 mph on the interstate. it's gets a strange sucking sound like the wastegate is opening (a tone change) and it loses about 10mph. If i push the clutch in and let it go to idle and then accerate again i can get a increase in speed.. then the "noise" comes again and it loses speed. The other 10% of the time i don't hear this noise and it just flies. The tech that has been working on this thing has checked everything he can think of.. fuel pressure and sensor readings. changed fuel and air filters. The sensors are in parameters while this is going on. (according to him) He's leaning towards a pcm replacement. I'm NOT a Diesel tech and don't pretend to be. No black smoke.. He's lost now... I have a few ideas but no solid previous experience to back up my theories in my own mind...
I need a few ideas to send this guys way before this truck gets someone hurt..
Any ideas will be appreciated
Thanks :headwall
 

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Maybe it's something simple like a boost leak at one of the hoses ?

That would cause your noise too.

I have seen turbo bolts come loose too,and cause the same noise and performance problems.The exhaust backpressure valve could be closing too.
 

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Discussion Starter #3
Hey Chris
He did tighten the turbo bolts a few weeks ago. and the hoses seem solid.
The backpresure valve(waste gate?) is the same idea that I have. I thought he said he changed a sensor there or something along those lines. That valve is elect controlled i assume. I asked if he could bypass the valve and he said you needed a special harness to do that. I would be great to get that locked and see if that takes care of the issues.
Keep you informed.
thanks :salute
 

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the wastegate regulates boost (intake side of turbo). if the pressure gets too high- the wastegate opens to bleed off the extra pressure. Some guys switch out their turbos for van turbos, as they don't have a wastegate, allowing higher boost pressures.

The EBPV is a valve in the exhaust that closes in order to put a load on the engine at idle. This helps it come to operating temp quicker. I think I remember dockboy telling me that he doesn't run an EBPV.
 

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EZSnow,

You are correct:nod4 I have not had an EBPV in my truck for over 60k mi. I removed it from my stock turbo when it was on, but now run a Van turbo which has no EBPV or wastegate.

Plow Dak,

If you say it runs good some of the time, I would be inclined to say that you have a sticking EBPV or a bad actuator. Can you hear the "hiss" or noise at the tailpipe? Do you have a boost gauge? If it were a leaky Turbo hose and you were losing boost, it would probably never run right when you got on it instead of just sometimes. If the EBPV is stuck closed, you will still be able to make boost, so thats why I asked about the gauge. I have blown off my fair share of turbo and intercooler hoses and when it happens, it won't run right until they are fixed:zoinks

The EBPV actuator is located in the turbo pedestal and it actually uses oil to operate. I can't remember which way (in or out) the rod is when the valve is closed. You may want to check and see if the actuator rod is still hooked up and hasn't fallen off or gotten jambed. There is a slide connector that holds the actuator rod to the valve arm. Changing the actuator is pretty easy but you have to pull the turbo. And if you had the turbo out, you might as well just get rid of the EBPV anyway. All it is is a big restriction in the exhaust. It's also easy to remove. Just unscrew the flap, pull the snap rings, drive out the shaft, then put 3/4" freeze plugs in the holes for the shaft:D

You can check the wastegate and wastegate actuator also, but it would have to be basically "loose" for it to run the way you describe. And if it was, it would never run right.

Let us know what you find ;)
 

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Is the EBPV also active while driving, or just during idling? At throttle settings slightly above idle while driving (cold), mine makes a hissing noise that really sound like the EBPV at startup, but louder since there's some throttle applied. Add more throttle or drop it completely, and it goes away. Defintely an exhaust-kinda-hissing noise, though.

Sorry, Plow Dak- don't mean to hijack your thread... we're all learning- right?
 

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EZSnow,

The EBPV will be closed, or partly closed, under cold conditions at Idle and under light driving conditions untill the Engine Oil Temp or EBP sensor sees a certain value. It's been so long since I've had a working EBPV, I forget the values;)

What happens while you are under light throttle and the EOT is still cold, the EBPV stays closed or partly closed. But when the Back Pressure gets to great(EBP Sensor), it opens completely. What happens to allot of people, especially if you have modded your truck for more fuel and it smokes, is the EBP Sensor gets clogged with soot and fails to operate. Then the EBPV stops working and people wonder why it doesn't "hiss" anymore ;) Also, because the sensor now reads "out of range Hi", the PCM defuels the motor at high rpms because it's trying to lower the back pressure:eek: I actually have a plug(dongle) that plugs into the EBP Sensor plug and it fools the PCM into thinking the back pressure is always low. That way I don't have to replace or clean the EBP Sensor every 15-20k mi. and I get maximum fueling:burnout
 

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Discussion Starter #8
Great guys,, thanks.
I'm going to copy this thread and hand it to the Tech.
this is excellent info.
I knew you folks would have some good info for me.
Thanks

I LOVE THIS PLACE !!!!!!!!!!!!:drinkup :drinkup :drinkup

Don't worry about stealing the thread EZ. The more info the better..
Dockboy, I can't tell to be honest if the hiss is at the pipe. I'm going about 50 more or less and sometimes slower... It just starts to take off and the falls on it's face... The tech thinks it's taking away fuel. It feels like it .. I'll see if he put a boost gauge on it tomorrow..
He has some more ammo now.
YE HAAAAAAAAAAAA
 

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Discussion Starter #9
Location

Finally the Tech is going to look at this truck. Where is the PCM in this thing. Lots of stuff around the dash and trans tunnel and I thought i would ask so he doesn't have to take something apart he doesn't have to.
Thanks
 

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Discussion Starter #10
Thought i would bring this back to the top. Many thanks to all who replied to this. it turns out it was the EBPV valve. we took it right out and it's a pleasure to drive again. Thanks Dockboy and EZSnow .....
 
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