John Deere Engine " Chuffing/ Fluttering?

[CrashWrench150]

Hello,
I have a Atlas Copco QAS-150kv generator.
It has a power tech PVX 6.8_6 cylinder diesel John Deere Engine. After it comes up to operating temp, it sits there and flutters or makes a chuffing noise.
The engine has a variable turbo charger on it. the
Actuator arm flutters it will not keep a constant rpm.
The turbo actuator module has been changed. It still makes the same chuffing noise.
I have changed all of the temperature and pressure sensors on both the exhaust and intake manifold.
Also the EGR cooler the bypass valve the sensors for it have been changed and the intake manifold air valve has been changed too. When you put the engine under full load, it stops chuffing.

 

[CrashWrench150]

Hi,
The Atlas Copco generator I am working on, the
John Deere Engine does not smoke, does not use oil, starts good, compression test is good on all cylinders. I have access to John Deere's diagnostic laptop. There are no trouble codes showing. All sensors and wire harness show okay. As said above, changing all of the pressure and temperature sensors, made the engine run a little bit better.
But still the same chuffing problem.

 

[heymccall]

Common rail injection or rotary mechanical injection pump?

Never mind. Reread. Has egr, so common rail.

You have software, so...does rail pressure vary, matching the flutter rate?

 

[MarshallPowerGen]

If it's an issue with hunting unloaded and stabilizes at full load, you might need to look into the sensitivity/stability settings.

Can always start out old school and check your exhaust manifold with a temp gun to be sure it's not a fuel/compression problem.

 

[Nige]

I see you did a compresson test but was a valve check/adjustment ever done.?

 

[mg2361]

Post a video of the issue fluttering/chuffing. Also supply an engine serial number.

 

[CrashWrench150]

Common rail injection or rotary mechanical injection pump?

Never mind. Reread. Has egr, so common rail.

You have software, so...does rail pressure vary, matching the flutter rate?

Good Morning Heymccall,
Yes, common fuel rail . According to "the JD Laptop, the fuel pressure are in specifications". The fuel
Pressure sensors have been replaced also. The rail
Pressure is " rock steady".
My Boss did a " cylinder/ injector drop test" , all Good Within specifications.
The software has been updated in the original
Computer. A new computer was tried, but still the same chuffing/problem. Put the old computer back
On, same chuffing/ problem.

 

[CrashWrench150]

If it's an issue with hunting unloaded and stabilizes at full load, you might need to look into the sensitivity/stability settings.

Can always start out old school and check your exhaust manifold with a temp gun to be sure it's not a fuel/compression problem.

Good Morning Marshall PowerGen,
Yes, tried changing the "Sensitivity/Stability" settings, it did not help.
This being a generator setup, it will not allow to Much Variation in "RPM's " . There is a computer for
the generator, which keeps track of the "RPM's,
Voltage and Amperage outputs. If this computer
detects a ie: over RPM's/ over voltage, under RPM'S/ under voltage, loss of engine oil pressure,
hi coolant temperature, low coolant level in reservoir, coolant pressure ( bad radiator cap ),
something wrong in the generator it self ,
It will go into " Emergency Shutdown".
I did check the exhaust pipe temperature, with a
IR Temp gun and " JD" Laptop . ( There are exhaust
temp sensors in the pipe). All good.

 

[CrashWrench150]

I see you did a compresson test but was a valve check/adjustment ever done.?

Good Morning Mr. Nige,
The engine has, 2,900. HRS. on it.
Yes, both a mechanical compression test and a cylinder/ injector drop test ( with the " John Deere
Diagnostic laptop). All test were with in a 10-30 rpm
Range . Valve lash within; .001- .0025 inch. Adjusted valve lash. All with in specs.

 

[CrashWrench150]

Post a video of the issue fluttering/chuffing. Also supply an engine serial number.

Good Morning mg2361,
The serial number is # PE6068R058676 .
John Deere ID#6068HFG94.
6 cylinder turbo diesel engine.
All this time , it has not shown a "Trouble Codes".
I have a video, need to change the file name.

 

[CrashWrench150]

Good Morning to all,
My Boss has had several " John Deere Tech's " to
Come out to look at this . One tech said, yep! Computer is bad! ( He never touched it, did not
Hook his Laptop to it )! Next Tech, did check out the
Computer ,sensors ,wire harness and turbo vane
Actuator ( I had already changed it) found nothing
Wrong, No Trouble Codes. Another Tech ,come by
To look at it. He seen the old turbo actuator laying
On my work cart , picked it up and anti freeze came
Out of the two bottom ports . YES, There is your
Problem! ( I TURNED AND WALKED AWAY !!! ).
The two ports on the controller, are " for coolant
Lines" to it, to cool the controller. Another Tech
Came by with a second Tech ( tag - team , HA ! )
TO work on it. Both said , the computer is bad .
They replaced the computer, No Change, Same Problem. Put the old computer back on, updated
The software ( original, never been changed before)
Same Problem, No Change. These two " TECHS"
recorded what it was doing and said they would
Talk to their 'JD Engineers '.

 

[CrashWrench150]

Good Morning to all,
So , I have already done a " PM service" on it.
All filters , all fluids ( including the engine coolant).
It has fresh diesel fuel, no water in the fuel tank And Filters.
one of our " peanut gallery ( supervisors ) " said
" The alternator/ generator is bad ! ". I told him,
" I had already rebuilt it along with updated switch
gear , circuit breakers , display/controller for the
generator itself". ( With help from Atlas Copco's
Techs, video chat).
another mouth said ," engine is bad"! . I said,
it doesn't burn oil, it doesn't overheat, it doesn't
use oil / leaking . Starts very good , cold or hot .
Again , No engine Trouble Codes.

 

[mg2361]

I have a video, need to change the file name.

You will have to make a YouTube video and post it.

Did the unit sit for a long time without use?

 

[CrashWrench150]

Hi mg2361,
Sorry , I got pulled off to do another job.
Came in last (03/27/2024) Wednesday and the
Generator had been taken to a John Deere Engine
Shop by my supervisor. I didn't get to finish it.
Oh Well ....... Oh ,you asked if it has sat for a extended period of time, YES, but it has a "auto start system on it.
Thanks to everyone who chimed in .
Catch you all on the flip side.
Thanks again, Mark.

 

[mg2361]

Let us know what the dealer comes up with.

 

[thepumpguysc]

PLEASE.. inquiring minds want to know..

 

[thepumpguysc]

U don’t suppose it’s something between the gen and engine scraping.?? And when under a load it stops..

 

[thepumpguysc]

I had an engine 1 x that was freshly rebuilt and had a tick..
Mechanics tore it apart 2x..
The faster the engine rev’d the faster the tick would get..
Come to find out the baffle in the VALVE COVER came loose and was ever so slightly touching the rocker.. lol

ALWAYS check your baffles.. lol