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Its a diesel you no about diesels. 2004 not sure. Its a

Its a diesel you...

Its a diesel you no about diesels

Mechanic's Assistant: How old is the engine? And when was it last serviced?

2004 not sure

Mechanic's Assistant: What is the make/model of your car?

Its a truck do you guys have information on diesel trucks

Mechanic's Assistant: Are you fixing your vehicle yourself? What have you tried so far?

Yes

Mechanic's Assistant: Anything else you want the mechanic to know before I connect you?

Diesel is surging at low idle and is limp mode

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Answered in 49 minutes by:
3/11/2018
GM Tech (Cam)
GM Tech (Cam), Chevy Technician
Category: Chevy
Satisfied Customers: 30,405
Experience: GM Grand Master Technician 2007. 14 years experience.
Verified

Hello there, I am Cam.

I am Licensed technician at a GM dealership with more than 16 years experience. 
Like you, I am a user of this website and as such, any billing questions should be sent to customer service.

I ask that you please provide details and communicate with me so we can make your experience here worth 5 stars! I am around most days but not every minute of every day. If you reply while I am offline, I will respond when I am next online. 

I am reviewing your request and will post in a moment.

What is your truck make and model please.

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Customer reply replied 4 months ago
2004 chev 6.6 duramax diesel

OK the I'm your man.

Are there any codes set?

Is this the LB7 or LLY?

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Customer reply replied 4 months ago
lly p0088 I have changed out fuel rail regulator
Customer reply replied 4 months ago
still surging at low idle and code p0088 came back on

Was this the pressure regulator on the pump or the pressure sensor on the fuel rail itself?

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Customer reply replied 4 months ago
actually I changed both
Customer reply replied 4 months ago
the one on the rail is the low pressure one right

on the 2004, the one on the rail is the sensor and the one on the pump is a regulator. On 2011 it changes and there is a regulator on both.

So is there wiring issues between the ECM and the regulator on the pump?

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Customer reply replied 4 months ago
sorry im lost now I wouldn't now about wirring issues

There regulator is run by the ECM and there is wiring that runs from the regulator to the ECM. It runs through the 2 large connectors at the drivers valve cover. These are common for wiring issue in that connector and open circuit would cause this.

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Customer reply replied 4 months ago
I have to go when I get back can I just call you and maybe we can figure this out how late are you on line I would rather talk to you

I am around most of the evening, but planning on movies with my family. Chat works better at the moment.

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Customer reply replied 4 months ago
how do I get back to you when im back on

Please be sure to save this page as a favorite in your web browser so you can reply back to me easily. you can reply at an time, even after accepting or rating me.

GM Tech (Cam)
GM Tech (Cam), Chevy Technician
Category: Chevy
Satisfied Customers: 30,405
Experience: GM Grand Master Technician 2007. 14 years experience.
Verified
GM Tech (Cam) and 87 other Chevy Specialists are ready to help you
Ask your own question now
Customer reply replied 4 months ago
Cam its dave again with the 2004 chev duramax LLY
Customer reply replied 4 months ago
the surging at low idle and its in limp mode

Did you have a chance to look at the wiring?

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Customer reply replied 4 months ago
I looked ball looked good no breaks

ok, does your scanner show live data? IF so, with the key on and engine off, what is the fuel rail pressure show?

Is there a chip or programmer on your truck?

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Customer reply replied 4 months ago
26106
Customer reply replied 4 months ago
no chip or programere
Customer reply replied 4 months ago
I just started it scan tool is reading 9200 psi for fuel press at idle at 720 RPM
Customer reply replied 4 months ago
if my primer on fuel filter was letting air in would it cause some of theses issuse
Verified
Phone call session started
Customer reply replied 4 months ago
you still there

Sorry yes, was out for a run.

So its reading 9200 for actual pressure, what about desired pressure? The system works by having the computer request the pressure it wants, and then the system responds. It needs to be with in 2 MPA or about 300 psi at all times. When its outside of that 300psi range from desired is when it sets that code, a P0087 for too low and 0088 for too high.

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Customer reply replied 4 months ago
ya the only code im getting is the 0088 one about the primer does that effect any thing

Leaking primer would go the other way, a p0087 and lower pressure not a higher pressure.

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Customer reply replied 4 months ago
ya I don't have anything but that scan tool so I don't no what the desired pressure would be

Ok so thats where we run into to issues. WE need to see what the computer is wanting and commanding for pressure as well as what the actual pressure is. Without that its hard to diagnose.

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Customer reply replied 4 months ago
well I cant do much without a machine so I don't no what I will do wait till I have extra cash take to service department

Unfortunately that is where we are at and I don't have any alternatives.

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Customer reply replied 4 months ago
ok thanks for the help
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GM Tech (Cam)
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