X15 Turbo Actuator failure?

[Josiah Harder]

Its been about a month since I first encountered this issue where my truck would start up and idle very badly with rpms fluctuating greatly and the fuel pedal wouldnt be providing any input past certain rpms and then not at all almost as if I was being derated. I restarted the engine and problem persisted but after shutting down for a couple minutes and starting again the engine ran perfectly. This happened again 2 weeks later and again resolved quickly after restarting the truck. I dismissed these events as random glitches until last week when it really worsened and I was having this issue every other day until finally last weekend I was unable to run my truck at all because it would start up and slowly die. Each time I tried to restart it the truck would run for less time till it would be stalling out almost immediately after start up. I had to get towed to a Cummins shop where they had no clue what to do because they had no active engine codes. What they did have though were inactive codes for the VGT actuator but they were reluctant to even consider that since it was inactive.
I should mention that a month prior to ever noticing the truck running weird on start up I was getting codes for that VGT actuator that would only come up at key on or start up but was told by several shops that it could just be a voltage issue tripping the ECM up. That was before any problems actually occurred so I dont blame them.
Cummins inspected my turbo and my actuator, both functional even voltage tested my actuator I think. They checked my EGR cooler and removed and cleaned EGR valve. All good yet truck still wouldnt run by the end of the day.
Next morning truck started and ran fine even though nothing was done. Cummins replaced my fuel filters preemptively even though they only had 13k km on them and I left the shop with a big bill.

The very next morning I encounter the exact same issue and thought I would need a tow again. I tried restarting the engine several times and waited in between till it finally ran normally and I left it on till I got to the nearest Peterbilt.
One thing I have come to notice and be sensitive to is the sound of the turbo upon start up and how it sounds abnormally loud every time I encounter this issue. If I can hear the turbo spooling louder than normal as soon as the engine is started I know im going to have issues.

I wont always have a check engine warning when I notice the issue so its very odd. But Peterbilt was able to see that for the latest event I did have only 1 code for my VGT actuator though it was inactive.

Peterbilt thinks I will need a new actuator though they havent had the chance to fully diagnose it yet and will be doing that on monday.

Im posting here for your guys input and maybe some suggestions I can do or pass on to the mechanics to make sure they check everything. I cant afford to leave this shop and encounter this problem again on the road requiring me to be towed again.

Ill include links to 3 videos I uploaded to Youtube showing how the truck is running. In the 2nd video you can hear the turbo sound I mentioned which will subside after the truck runs for a bit.
Youll notice the RPMs going up and down but thats not me using the pedal the engine is doing it on its own.

https://youtu.be/BKbpnK2bjpY
https://youtu.be/ZM-omNKXtZI
https://youtu.be/_xSchL7N6Ro

My truck is a 2019 Peterbilt with an X15 efficiency series with 450hp. It has 950,000km on it so its getting quite high up there where I shouldnt be surprised if these things are failing I guess

[Bengy88]

Ok to start… is this truck demandated?

Second. In my experiences (I’m not saying it can’t) but I’ve never had a vgt actuator cause the exact issue you are describing…. I have had a turbo clogged with soot cause something really similar to this and 90% of the time when a turbo is giving issues the first thing to code is the vgt actuator. I know you said they checked the turbo but who’s to say they actually knew what they were checking. We will all tell you that 90% of dealership mechanics are just parts changers and just throw parts and guess. I know from experience…. I used to be a dealership mechanic. I would also be interested in the health of the circuits to the vgt actuator and the ecm it’s self. Just thinking out loud here. Some of us could tell you a little bit about what’s going on if you had insite hooked to it but without it we can only play guessing games.

Also. I wonder what the condition of the fuel pump is with over 500k miles on it. The problem you are having could be completely un related to the turbo or vgt and more fuel related.

[Josiah Harder]

(02-10-2023 )Bengy88 Wrote:  Ok to start… is this truck demandated?

Second. In my experiences (I’m not saying it can’t) but I’ve never had a vgt actuator cause the exact issue you are describing…. I have had a turbo clogged with soot cause something really similar to this and 90% of the time when a turbo is giving issues the first thing to code is the vgt actuator. I know you said they checked the turbo but who’s to say they actually knew what they were checking. We will all tell you that 90% of dealership mechanics are just parts changers and just throw parts and guess. I know from experience…. I used to be a dealership mechanic. I would also be interested in the health of the circuits to the vgt actuator and the ecm it’s self. Just thinking out loud here. Some of us could tell you a little bit about what’s going on if you had insite hooked to it but without it we can only play guessing games.

Also. I wonder what the condition of the fuel pump is with over 500k miles on it. The problem you are having could be completely un related to the turbo or vgt and more fuel related.

Thanks for your thoughts. The truck is not deleted and youre right the turbo could be going bad since it has almost a million km or 600 miles and Im not sure I trust the thoroughness of the last Cummins shop I was at. I will get Peterbilt to inspect it well. I myself tried to inspect the circuit and couldnt see any possibility of it being bad since the whole circuit is well covered in tubing and secured to the engine with no way of rubbing through. It all looked good to me unless maybe the pins in the plugs are bad.

I guess its pretty hard to figure out from just a description and few video clips yeah. Do you know if its even possible for the actuator to completely close the turbo and choke the engine? Seems odd there would even be a setting to suffocate the engine like that. Maybe its a fuel pump is that something that should be giving a code though for low fuel pressure?

[Bengy88]

I would say it’s completely possible. I’ve just never seen it myself, I’m sure someone here has though. I would say start with the known issue. You know your vgt actuator has a problem going on somewhere. Find that problem and fix it and then see what happens. It needs to be repaired anyway to keep your engine performance, emissions, and engine working properly. But most likely whatever is causing your vgt code is causing your other issues.

Just my opinion. But it appears your vgt is causing your turbo to spool very high on first startup and after it runs a second and doesn’t adjust properly then it’s hanging one way or the other. I wonder when you switch the key on does your vgt actuator make a full sweep back and forth or does it make a humming noise halfway through the sweep? Or maybe your ring inside your turbo is hanging and causing all of these symptoms, or maybe your turbo is just soot loaded, I’ve seen soot loaded turbos come from bad injectors, boost leaks, egr neglect, etc. Like I said I’m not saying these are your problems but you know there is an issue at your turbo or vgt actuator and an engine needs to have exhaust flow to run.

[schISM]

Sounds like the VGT/Actuator is nearing the end of its service life. Reference this thread

https://rawze.com/forums/showthread.php?tid=2290

If it’s only throwing codes for the turbo that’s where I’d start

[tree98]

Did someone have the actuator off right before this started happening? If so they might not have calibrated it and now the ecm doesn't know what position it's in. To me it sounds like the turbo is choking the engine off. You don't show a clear view of the tach in those videos but from what I could tell it doesn't appear to be rev-ing it seems to be dropping rpm from idle speed.

If you had insite you could take the actuator off and inspect the turbo VG ring

https://youtu.be/ZUpKb5umv_0

and if it checked out you could then calibrate the actuator and put it back on.

You could also run the hysteresis test (turbo test)with insite, and a fuel system leakdown test.............for about $300 you could get an inline adapter and the software needed to stay far away from the parts changers who will only drain your bank account and leave you stuck on the side of the road somewhere. What exactly was the inactive code that it had? We're all just blindly guessing here with zero information to go on.

[Josiah Harder]

(02-11-2023 )tree98 Wrote:  Did someone have the actuator off right before this started happening? If so they might not have calibrated it and now the ecm doesn't know what position it's in. To me it sounds like the turbo is choking the engine off. You don't show a clear view of the tach in those videos but from what I could tell it doesn't appear to be rev-ing it seems to be dropping rpm from idle speed.

If you had insite you could take the actuator off and inspect the turbo VG ring

https://youtu.be/ZUpKb5umv_0

and if it checked out you could then calibrate the actuator and put it back on.

You could also run the hysteresis test (turbo test)with insite, and a fuel system leakdown test.............for about $300 you could get an inline adapter and the software needed to stay far away from the parts changers who will only drain your bank account and leave you stuck on the side of the road somewhere. What exactly was the inactive code that it had? We're all just blindly guessing here with zero information to go on.

Hey yeah you're right it's not reving it's just dropping rpm from idle speed. No one had that actuator off before this happened so it wouldn't be a calibration issue. I'm not sure what the exact code was but it was for the VGT actuator is what I was told. I'm only 6 months into being an owner operator but Im quite certain I will be investing in the tools to do more work myself after this experience. Been waiting 4 days just to have the shop look at the truck and that's the case everywhere it seems. I didnt think InSite could be purchased by individuals though and thought it costed tens of thousands of dollars. There are some other products like Bosch and OTR performance I was researching though.

[tree98]

(02-11-2023 )Josiah Harder Wrote:  There are some other products like Bosch and OTR performance I was researching though.

For a cummins engine you want insite and only insite. One like this would be just fine.

https://www.ebay.com/itm/394344041238?mk...media=COPY

They say they have version 7.6.2 and version 8.7 since you have an X15 get the 8.7

[SquareOne]

Tree, will 7.6.2 work with the X15 or would I need to hunt down 8.7? All the trucks I'm currently hunting have X15's which is why I ask.