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Discussion Starter · #1 ·
I have a 2000 7.3L PSD. Recently, I went through a lot of preventative maintenance for a family vacation out west. I was mainly trying to discover why this thing only seems to get 15/11 MPG! So I've swapped a number of sensors that seemed suspect and changed out the EBPV tube and sensor. After I did that I've heard the EBPV engage during warm up (ambient air 65F). It was just a light hissing, but enough to know that it was engaged, then after 10 mins it would go away on idle or immediately when I drove it. This is probable the first time that I've heard the thing engage and I live in Wisconsin and have owned the truck for 9 years! The tube and sensor were packed full so I had to replace them.

While during a test drive after doing the harpoon and hutch mod, stock turbo, stock tune, 4" Turbo back exhaust, Ram air intake, I've heard my wastegate flutter under hard acceleration. I read the forums and passed this off as "turbo surge" so I ordered the WW2 and a SCT flash tuner so the truck wasn't such a dog. So I played with 3 tunes and it woke the truck up, but suddenly my flutter problem was getting more prominent, so I installed WW2. (No play or binding in turbo shaft whatsoever)

After the WW2 (using the SCT for the gauge data), wastegate would dump the boost after about 7-10 PSI. If I drove over 55MPH, the wastegate would blow wide open. So I put the stock tune back in and unplugged the WG actuator and capped the bleed line and even unplugged the WG solenoid at the IC spider. I took off the wastegate actuator and tested it. The rod move at around 7 PSI So I maxed it out to hold the WG shut. This help it not blow till about 15 PSI, but still could not pull a trailer above 60MPH without a flutter and anything above 65MPH sounded like WG was open constantly. Throughout every test drive, when you let off the throttle with any boost over 7 psi, the WG would dump the boost and close under acel like a blow off valve. Strange!

So I replaced the WG actuator with an AFE actuator that is set at 40PSI. With everything still capped off, vacuum line wise (tested both ways), the WG still blows wide open after around 12-15PSI.

My thoughts - being that the EBPV had been sitting for so long that when it attempted to engage, it got stuck partially closed on some built up carbon. After that event, is it possible for the EBPV to be partially closed enough to create enough back pressure to blow open the wastegate during deceleration? That's over 40PSI! OMG! The computer can't seem to sense this because the MAP is on the compressor side of the turbo. The computer doesn't seem to set a CEL based on Back Pressure readings from the EBPS.

Anyone experience this issue? Never heard of anyone talking about WG opening during off gas.
 

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Wire the ebpv open or get rid of it. Mine would partially close as well and cause power and shifting issues. You can also unplug the connector at the base of the pedestal to make it stay open.

How are you reading ebp?

Backpressure should be equal to boost at anything under 20 psi. After 20 psi backpressure starts to get a little higher. Obviously if your ebpv is staying closed that's going to make it a lot higher.

Also you will never hear a wastegate on These trucks. They just don't make enough noise to be heard over the loud engine.
I'm thinking you might have an issue with a torn intercooler boot or some other boost/exhaust leak.
 

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Discussion Starter · #3 ·
Quick update - I unplugged EBPV actuator at the pedestal wiring connector. I was able to verify the EBPV seemed to be in the open position (the bottom of the butterfly is against the tang) and I was able to move it by pushing on it (yes my EBPV actuator rod is leaking) and it seemed to return back to the tang. I took it for a test and no change.

I think I can rule out the EBPV as the problem, but I'm still really confused.

I do have to admit it does sound like when you have an IC boot blow off. The difference is that I don't seem to lose power. It could be on the exhaust side though.

It never happens under boost and it sometimes occurs when you hit a bump in the road normally driving over 55mph.

Under 50mph everything is normal unless you're stomping on it.
 

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Discussion Starter · #4 ·
Wire the ebpv open or get rid of it. Mine would partially close as well and cause power and shifting issues. You can also unplug the connector at the base of the pedestal to make it stay open.

How are you reading ebp?

Backpressure should be equal to boost at anything under 20 psi. After 20 psi backpressure starts to get a little higher. Obviously if your ebpv is staying closed that's going to make it a lot higher.

Also you will never hear a wastegate on These trucks. They just don't make enough noise to be heard over the loud engine.
I'm thinking you might have an issue with a torn intercooler boot or some other boost/exhaust leak.
I was using the SCT flash tuner to read EBP, but it was saying it was 175psi, and something like 85psi with engine off, so I ruled that out as credible. There may be an ECU problem too that I'm unaware of. Is there a better way to read EBP? I don't have any gauges yet so I'm probably shooting blind on this. I was mainly trying for better fuel economy added performance is a bonus, but I wasn't trying to get too crazy with mods.

It seems to happen after you let off the pedal and the turbo spools down from a boost of over 10psi. Maybe the turbo can't take the boost anymore and starting to take a dive, but I'd really like to narrow things down before I invest another $2k in a rust bucket. In has 180k on the engine, so it's worthwhile to fix, but I need to budget the repair.
 

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Discussion Starter · #5 ·
I am going to make a boost leak detector that I'll hook in-line with my home made smoke tester. If there are any leaks I should be able to find them quickly. This will only show leaks on the compressor side correct? I know my IC boots are good, but will be interesting to see. I did the CCV delete mod so I won't be pressurizing the crank.:lol:
 

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It's easy to check for shaft play.

In and out play is bad. You can have very little side to side play.

Check the compressor housing for blade contact.
 

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Have you checked the up-pipes for leaks?
 
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