OK. So was at a family members for easter dinner on Sunday and meet a guy who had a mechanic shop a couple towns over from me. He has a couple Ford tow trucks, one with a 7.3 and one with a 6.0. He has had great luck with both.

Anyways, we were looking over my truck and when I told him I had a EGR delete he said to get rid of it because:
"The EGR system works as the blow off valve for the turbocharger, and if it gets deleted, your cylinders will see higher than normal boost pressure when you let off the throttle"
Does this make any since? I know there is no blow off or wastegate on the turbo, but thats not required for a VGT system system right? And since a diesel does not have a butterfly valve like a gasoline motor, boost wouldnt build when the throttle is released.

I'm pretty sure he has no idea what he is talking about, or maybe he is on to something. I just want to see if anyone who is experienced with these trucks can back me here.

 

You are fine. The egr valve is not used like that.

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But, can it really increase enough to damage or stretch the bolts?

https://www.ford-trucks.com/forums/1...l#post14186328

 

No, not a worry, boost is controlled by the VGT and is limited to 26 psi. If however, the VGT or unison ring are not working correctly, this can cause an over boost, but there is no strategy to use the EGR circuit to reduce boost that I am aware of.

 

It's not strategy, the spring in the egr valve acts as a blow off valve. I was told this by a ford fse.

 

http://www.powerstrokediesel.com/docs/EF_456.pdf

Look at the design of the valve, there is no way that it is going to act as any kind of a blow off valve.


The FSE is an idiot.

 

So, when the boost pressure overcomes the exhaust pressure when the throttle is let off at high rpm/high load that valve won't open? Explain this to me.

 

Did you look at the valve?

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Yes.... Have you? The boost pressure pushes down on the top part of the valve, exhaust pushes up, when the pressure on the top overcomes the pressure on the bottom the valve will open.

 

The exhaust comes through the middle of the valve...

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So after reading through the attached tech manual, and doing the research that I've done, I'm convinced that the EGR valve does Not function as a "blow off valve".

Here's why:
"The EGR valve is opened during steady
state throttle positions when exhaust back
pressures are higher than intake manifold
pressures (boost)."

So what thats saying, is that the EGR only opens when the turbo is not under boost, as soon as you "get on it" and create boost, the EGR valve will shut and allow boost to build. This makes since because I've drove around with a scan tool that allows you to see the EGR valve position, and the only time it is really open is at idle-1200 rpm. If you driving and get on the gas and create boost, its shuts.

So with that being said, it wouldnt make since for the valve to open to depressurize the pressurized intake manifold to the exhaust system. The valve would be working against the turbo pressure...

This is just how I believe the system works, I'm an engineer and spend hours every day reading through tech manuals and troubleshooting complex machinary. If an actual Ford Technician can say other wise, well i'll wait for that to happen...