That's compressor stall. In gas vehicles, we use a blow-off valve (separate from wastegate) to prevent this problem, which can cause turbo damage - bearings don't like it - but I don't know what you'd do on a diesel because on a gas this problem is caused by closing the throttle plate which diesels don't have.

 

Diesels get the same thing by backing out of the throttle at high boost levels. The piston velocities change so the air required by the engine does too. Same principle. And yeah that sound may sound cool, but it really pisses off your turbo. A BOV is still a viable solution it just has to be set at a higher boost level than what you plan to operate the turbo.

 

Here is a good explanation and recording of what I would call turbo surge. Albeit it is a gas burning ricer, but you get the idea.

<iframe width="420" height="315" src="http://www.youtube.com/embed/nCj6Spwl1CU" frameborder="0" allowfullscreen></iframe>

I guess in principle it is the same thing as the "bark" I was talking about but the difference being that it is happening when you're in the throttle and the compressor can't flow any more air into the engine. I am guessing that this car has neither a BOV or a wastegate, as I can't see it doing this unless it didn't have either one, or they were adjusted incorrectly. Anyway, I digress as this little tangent doesn't really have anything to do with solving the OP's issue.

 

Well after listening to the video what i'm having happen does not sound like that at all. I may be imagining what I'm hearing more than hearing it, but it is a muffled sound incorporating the turbo whine. I am starting to wonder more and more if it is a boost leak... I will not know till i get a boost gauge on there. I am planning giving a stab at getting the entire setup welded the weekend after this one and hoping the new boots and new plenums will solve any concerns of a boost leak.

Are there any threads regarding removing the intake plenums? Replacing them with 3 inchers. Once I get this done I will throw a gauge on there and see what happens. Untill then its towing in a stock tune. I will be quite happy when i get to the bottom of this....

If its not a boost issue then I'm wondering what is next....

 

Do you still have the EBPV plugged in by chance?

 

I'm guessing so, I have never unplugged it. Where is this located?

 

You might want to unplug that thing and see if it acts any differently. It is a 2 wire connector under the intake side of the turbo. The EBPV is a flapper valve in the exhaust outlet of the turbo that is supposed to close to aid in warmup when it is cold outside. However, they are known to close when they shouldn't. They typically make a distinctive "whooshing" sound but if your happens to be closing it would certainly account for your high EGTs and strange sounds from the turbo. They usually malfunction due to a cracked or clogged EBPS (Exhaust Back Pressure Sensor) Tube. The EBPS is at the front of the engine, up top right beside the square HPOP reservoir. It has a tube that runs down to the passenger side exhaust manifold. That tube gets clogged or cracked then the sensor reads incorrectly or not at all and the flapper valve (think throttle butterfly on a carb and you're not far off) can close when it shouldn't.
I would unplug it and see if it makes a difference. It won't hurt anything to unplug it. In fact quite a few guys here, myself included, have completely eliminated the entire EBPV.

 

damn I'm headed down to the garage to do this...going to see how it reacts in the morning....

 

Ok its unplugged...pretty sure I got the right one. Its a plug with two larger pins correct? at the base of the turbo under the intake hose? When I unplugged it, the plug itself was coated in oil and the two plastic prongs were cracked. If anything it wasn't making a good connection. I'll give it a hard run in the tunes without towing and see if there is a difference. I won't be able to know for sure till I pull something behind the truck.

It would be nice if this were as simple as this..jsut have that gut feeling it may be a bigger issue.



Any one have a link to what it takes to install new plenums?????? Not sure what all needs to be removed under there to do so since this is my first go at it.

Part number for the special grey ford intake plenum sealant???? Who carries it?

 

That's the one! Here's to hoping it is something as simple as the EBPV!

I am no help on the plenum swap, but as for the special Ford Silicone, you will have to get it at the dealership or from Riffraff Diesel. It comes in a short caulk tube, and I want to say I paid around $20 for mine the last time I got it. Just tell them you need some of the special silicone for a 7.3 Powerstroke. They will know exactly what you mean. It actually says it is for the Powerstroke right on the tube. It's good stuff.

Edit: I found a part number and oddly enough it seems they spec a different sealant for the intake plenums than they do for the rest of the engine. And riffraff carries the TA 31 but not the TA 30 that is recommended for the plenums. I'd like to hear someone else confirm this as I though that the agreement was generally that the TA 31 could be used for the plenums as well.

"RTV Silicone Sealer (special sealant for powerstroke)
(Ford) F5TZ-19G204-AB (5oz caulk tube for oil pan etc)
(Motorcraft) TA-31 (5oz caulk tube for oil pan etc)
(Ford) F7AZ-191554-EA (5oz, 1/2 caulk tube for intake plenums)
(Motorcraft TA-30 (5oz, 1/2 caulk tube for intake plenums)
(Wacker) T-442
(Internatioal) 1830858C1



Not sure if this is 100% up to date but it should help esp for online ordering.

In Edit TA-31

 

Well I really did not notice a difference this morning... like I said I will not be able to really test it till there is a load behind. I hope that valve is not stuck in a certain position and I do not know it. Is there some thing I should be listening for in tone when its unplugged?

Thanks for the heads up on the sealant. I will try to find out what the exact number is and go pick some up.

 

Typically if the EBPV is plugged in and working as it should be, when you start the truck it will cycle closed and then open again. You will hear the sound of the exhaust change and then go back to normal. When it closes you can hear it kind of whoosh like there is air under pressure escaping. If you have the time and want to check it the easiest way to be sure where it is at is to disconnect the downpipe and then look in the turbo outlet. You will see the butterfly valve there in the outlet. You can try to operate it by hand as well, but it is difficult to reach or see the linkage since it is under the turbo outlet and with the firewall and cowl in the way you can't really get back there to see it unless you use a mirror. There is a rod that actuates the butterfly valve and I want to say that the rod is extended toward the passenger side of the truck when the valve is open, and then pulls back into the turbo pedestal to close the valve. I can't remember for sure which way it mopves to close the valve though so your best bet is to see if it will move freely (there should be spring pressure to hold it open) or to pull the DP and take a look see.

Here are some pictures for reference:

 

I've gotten my stock charger to surge, and let me tell you. It is hard.

Very very very hard. I had a sensor issue at the time, so it was causing some weird stuff to happen.

Gqqsb is a 450-500 hp turbo.
She's an idiot.

Actually, it looked more like she was just trying to sell you expensive turbo's which wouldn't fix your problem.
Yeah, the 38r is good too, but you'd have to buy so much stuff to get any of those turbo's to work.

The stock charger on our trucks is amazing.

Lots of good info in this thread to help you out.

Make sure that air filter is clean and check the other stuff these guys are suggesting.

 

It sounds like once you get up to a certain boost pressure, you may have a good sized boost leak or drive pressure leak. Build yourself a boost leak detector or buy one, hook up the air compressor, and spray down the connections with soapy water to find any leaks. Also, check the uppipes for signs of an exhaust leak(IE soot on pipes or firewall).

 

Agreed.




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