2005 8.9 ISL needs key reset to run properly

[All_Mountain]

Yesterday a new boost pressure sensor was installed on the engine.

This morning I went for a test drive. Yesterday, I had noticed that at idle, when the engine was running properly, I would have 1.3 psi of boost pressure. This morning when I started it, it read .1 (zero) on my ScangaugeD.

I also noticed when I was doing my pre-drive walk around that I never heard the turbo whistle like it normally would.

I did the test drive and sure enough the engine did not work properly.

I called Cummins of Kenly and they told me not to turn the coach off. Last night the service manager was at home thinking about my problem. He thought maybe it could be a stuck air control valve to the turbo. Maybe some moisture got back there.

I told him my air line from the air control valve to the turbo actuator was replaced in July of 2019 because it had a hole rubbed into it from the transmission dipstick tube. It took me about four months to find the leak so more air than normal would have flowed through the valve. (I'm a little slow finding air leaks. I had called Spartan and Newmar and told them my dryer was cycling too much and I was losing air pressure only when the engine was running. I could sit on or off airbags and the pressure would leak down very, very slowly)

They hooked up the Cummins INSITE computer and ran a turbo test. The turbo never whistled and the actuator never moved. It failed the test.

They asked me to turn off the engine and restart it. Immediately I saw 1.3 psi of boost pressure on my ScanGaugeD. They ran the turbo test again and during the test the engine rpm cycles, the actuator stroked and you could hear the turbo whistling (like normal). Guess what, it passed the turbo test.

They are ordering a new air control valve, P/N 3770743 from Cummins in Atlanta. It should be here in the morning.

My current opinion of Cummins of Kenly is that they are a good shop. They seem compassionate and caring and give me the impression they are doing their best to get me out of here. They are going to reinstall my original boost pressure sensor and the new air control valve in the morning with the engine cold so I can test drive it tomorrow and possibly leave, not losing another day.

I spoke with another coach owner this morning that has been bringing his motorhomes here every year since 2007 and he felt the same way. This is a good shop with caring people. Unfortunately a sticking turbo air control valve doesn't set a check engine light because electrically it is working properly. It does not have a position indicator for the ECM to know it didn't cycle.

Let’s hope this solves my problem. Stay tuned.

[All_Mountain]

Cummins of Kenly installed the new turbo air control valve this morning and reinstalled my original boost pressure sensor (located on top of inlet manifold behind the inlet elbow).

Here are a few things that I learned during this ordeal.

- If my ScanGaugeD doesn't read about 1psi at idle it's not going to run properly
- If I don't hear the turbo whistle once the bus airs up to a high enough pressure to actuate the turbo VG (variable geometry) actuator, it's not going to run properly (this also makes the turbo whistle I believe)
- If the turbo actuator is bad (it has a diaphragm in it, not a piston) it will leak air. You won't be able to hear it with the engine running. It's a lot easier if you have a computer with Cummins INSITE on it because you can command the actuator to cycle (put air on it) without the noise of the engine. Or you could connect an air line to the actuator and pressurize it with another air source.

Now I'm hoping the Cummins Customer Advocacy team will make things right. My bills have added up to $5813.47 If you read through this thread you will see all the work that was performed.

4 hours of labor and a new turbo air control valve is about $2200, not $5800.

I will let you all know how I make out with Cummins. I'm very hopeful. They definitely seem like they want to help.

[Ljwt330]

Originally Posted by All_Mountain

Cummins of Kenly installed the new turbo air control valve this morning and reinstalled my original boost pressure sensor (located on top of inlet manifold behind the inlet elbow).

Here are a few things that I learned during this ordeal.

- If my ScanGaugeD doesn't read about 1psi at idle it's not going to run properly
- If I don't hear the turbo whistle once the bus airs up to a high enough pressure to actuate the turbo VG (variable geometry) actuator, it's not going to run properly (this also makes the turbo whistle I believe)
- If the turbo actuator is bad (it has a diaphragm in it, not a piston) it will leak air. You won't be able to hear it with the engine running. It's a lot easier if you have a computer with Cummins INSITE on it because you can command the actuator to cycle (put air on it) without the noise of the engine. Or you could connect an air line to the actuator and pressurize it with another air source.

Now I'm hoping the Cummins Customer Advocacy team will make things right. My bills have added up to $5813.47 If you read through this thread you will see all the work that was performed.

4 hours of labor and a new turbo air control valve is about $2200, not $5800.

I will let you all know how I make out with Cummins. I'm very hopeful. They definitely seem like they want to help.

Great news and thanks for the updates.

I followed this entire thread for educational purposes, even though my own engine does not have the same turbo set up. One question, however. Obviously the turbo actuator did not fail due to a bad diaphragm, otherwise an ignition reset would not "fix" things. Can we assume, then, that the actuator has some electronic component with printed circuitry that was responsible? (I have never seen one.)

[All_Mountain]

Yes, I think it’s a pretty sophisticated electro-mechanical valve. I’m not positive but I think it adds or vents pressure to the turbo actuator so it can have an infinite number of positions. I don’t believe it either vents the spring loaded actuator (contracting it) or adds full air tank pressure to extend it. If that is how it works then the actuator would only have two positions, fully extended or fully contracted.

[Flanz]

AWESOME!!!!

I’ve been following this thread hoping that you and Cummins find the problem and fix your coach. Very happy that Cummins hung in there and your satisfied with the repair. We know what its like to be stranded and to try to get a repair shop to work with us. Especially when the problem is intermittent.

Now the fun starts. I hope that your successful with collecting any money due to you from unnecessary parts or shop time....Pleas keep us posted.

Good luck, and safe travels!

[c_oneil]

I had replaced my turbo air control valve and then dissected the old one to see how it works. The air control valve functions as a variable pressure regulator that uses a PWM signal from the ECM that is processed by a circuit board inside the control valve. The circuit board moves a solenoid, a small diaphragm and piston assy inside that are the mechanical parts of the regulator. The air tank pressure coming into the valve is regulated down as called for by the ECM and then piped to the separate turbo control actuator that is mounted on top of the turbo. The actuator is has a bellows and spring assy on the inside that pushes on the VGT turbo linkage when its input pressure is increased by the turbo control valve. The spring returns the actuator to its zero position when the control valve drops the input pressure. The turbo control valve does vent excess pressure by design when a pressure drop on the actuator is called for. The actuator does not vent anything unless it is failed and is leaking air.

What All Mountain says in post 18 is right on.

https://www.irv2.com/forums/f104/com...-386522-2.html Post #25 shows what the inside of the control valve looks like.

[All_Mountain]

Final update:

Cummins is a great company. I have signed a release agreeing to not share the details of my resolution, let me just say, “I will buy Cummins products in the future!”

[vito.a]

That's great!