Truck Repair 2008 Single Valve Cover CAT. HELP PLEASE!!!!

Thread starter #1
I have a 2008 peterbilt 389 with the single valve cover cat.
Engine came factory with twins and actuators and DPF filters of course....

It's haunted.

Looking for a guru....

Please read entire post before suggesting a fix.... as I will tell the whole story and what I have done thus far.

About six months ago the truck started vibrating/sputtering like it needed a fuel filter.
So I stopped and changed filters. It seemed to have fixed it. Until about 20 miles down the road it started sputtering again.

It continued like this until I got it back home. If you ask the truck for full throttle for too long it will start missing/sputtering etc....

It feels EXACTLY like a fuel filter.

So the first thing I did was replace the fuel lines.
Then I changed the draw tubes.
Then I put a new fuel pump.
Then I replaced the fuel pressure valve and the check valve in the filter housing.
Then I thought maybe air was getting back in the fuel so I replaced all the injector o rings.
Then I bought two new injectors and replaced #2 and #4
Then I swapped them to #5 and #6
Then finally I swapped them to #1 and #3

Nothing has changed at all.

The truck is fully deleted, and is set somewhere around 600-650hp

No DPF no intake actuators.

The truck acts the same every time, and is extremely consistent.

When you leave the house for the first time the truck will build 50-55 pounds of manifold pressure, and smoke slightly at full fuel.
After about 5 miles the truck will only make about 38-40 pounds of manifold pressure and no smoke.
That is the first step....

After the initial loss of power the truck will run that way for the rest of the day, unless you ask for full throttle for too long.

If you stay in it while pulling a long hill or if you run 75-80 mph for longer than a few miles then the truck will begin missing/vibrating/sputtering/etc... and will only make about 28 pounds of manifold pressure.

Once it does that if you keep your foot in it it will sputter all the way to Mexico. But if you let off and let it coast for a while it will come back and be the 38-40 pound truck again and run smooth. But will only go back to being the 55-60 pound truck if it is left at an idle for a while.

Like I said it is extremely consistent, which is what made me think it was gradual loss of fuel pressure... but the truck maintains 90 pounds of fuel pressure at every stage of its horsepower. Fuel pressure NEVER drops. That's with a manual gauge hooked to stratoflex at the fuel filter port.

The last piece of the puzzle I have will be for someone who has more knowledge than I do.

I hooked it to my laptop the other night.

While looking through different things in ET I saw something that said fuel delivery rate. And also something that said engine derate percentage.

My mechanic kept an eye on these two things while I held the truck at full throttle.
The engine derate percentage never changes. The engine IS NOT derating.

The fuel delivery when I first crank the truck is 585mm of fuel when held at full throttle. The truck will make 55 pounds of manifold pressure there.

When the truck falls to 40 pounds of manifold pressure the fuel delivery is showing to be around 480mm of fuel.

Any suggestions would be greatly appreciated.

Is a turbo failing? Causing air loss which translates to fuel cut back?
Or is there another fuel problem I could have?

6 months of hard searching and I finally need help.

Thanks for having me
 

r3gulator3

Friendly Neighborhood Former Technician
Staff member
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#2
First question I have, when was the last time you replaced the air filter?
 

r3gulator3

Friendly Neighborhood Former Technician
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#4
Was the code a 64-11 or. 64-9?
 
Thread starter #5
what code?

The engine is not throwing any codes
 

r3gulator3

Friendly Neighborhood Former Technician
Staff member
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#6
Ok so no codes thanks.
Single valve cover, so c-13?
 

r3gulator3

Friendly Neighborhood Former Technician
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#7
Have you verified fuel pressure with a mechanical gauge?
 
Thread starter #8
No. C15

Post says pressure has been verified
 

r3gulator3

Friendly Neighborhood Former Technician
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#9
I apologize I must of missed that. Saw a lot about manifold pressures. Ok well hip shot is a turbo issue or your fuel pressure regulator is sticking open under load.
 
Thread starter #10
Fuel pressure regulator has been changed.

A turbo issue can come across as a dead miss?
 

r3gulator3

Friendly Neighborhood Former Technician
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#11
You didn’t describe it as a dead miss you described it as a loss of power with a vibration. Which is comin when having fuel issues. And since you verified fuel pressure with a mechanical gauge and not a laptop that system should be in order.

Two things left turbo and cylinder pressures. Have you checked blow by?
 
Thread starter #12
Blow by appears to be normal.

Do you have an explanation as to how or why the turbo or blow by can intermittently cause loss of power and extreme sputtering?
 

r3gulator3

Friendly Neighborhood Former Technician
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#13
Not enough cylinder pressure,
 
Thread starter #14
Truck does not have excessive blow by. Turbos feel and sound like they are in good shape. No shaft play. Truck acts the same with or without the wastegate hooked up.
 

r3gulator3

Friendly Neighborhood Former Technician
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#15
what’s your injection acuation pressure actuator percentage with the pressure turned up full?
 

Dauntless

Active Member
#16
All Twin Turbo Cat Truck Engines had IVAs and those systems had a lot of problems. This video describes what they are, how they work, and how to troubleshoot them.
 

Dauntless

Active Member
#17
These engines are know for bad injector/IVA wiring harness. Check where the wiring harness connects to the valve cover housing. If there is lots of oil in that area that could be your problem. The oil shorts the connectors and gives you a bad miss. Sometimes mine will miss and briefly give me a code 74, on dash, injector 5 or 6 current high. I also have a 05 Cat 15 ACERT engine in a 387 Peterbilt. Had to change all the IVA connections on the harness.
 
Thread starter #18
The intake valve actuators have been deleted.
Can they still cause problems after deleting?

Also has anyone had a wiring harness issue that was this consistent?

Hard pull means harness failure... reducing throttle causes harness to make connection again?
 

r3gulator3

Friendly Neighborhood Former Technician
Staff member
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#19
Vibration yielded terminals and oil wicking are all common injector harness problems. Easy check is unplug your harness at the pass thru in the valve cover, if there is oil there it’s bad
 
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