Turbo Power loss Need help to diagnose

[JohnC3]

Hello Everyone, I have a problem I have seen here and could use some help trying to find a tool to find the real problem. I will (especially when going up/down hills have my warning light come on. This seems to frequently occur on a trip where turbo pressure drops to 0 for about 6 seconds when I am trying to accelerate. The Turbo recovers, I would describe it as it 'wakes up' after ~4 seconds and pressure builds and power returns. Couple of notes. Exhaust Brake use (or not use) has no impact on this. It happens either way. Occurrence is not frequent (Maybe every 6-8 hours of driving if there are hills, less frequent if flat). I have the Variable geometry Turbo that has an actuator to adjust the vane angle. The turbo will develop 33-35psi when fully engaged.

 

My first thought is the turbo itself seems ok, it will provide boost up to ~33psi as required (unless this issue is happening). SO I suspect the Actuator. But is thinking about this I am wondering if it could be the control signals (Sensor(s), connections, Control module, etc.). This is where I could use some help. I have had this checked more than once and no codes are thrown. The warning light comes on, but they cant see the cause for it. 

Is there a product that will let me record the sensor data and commands sent to the turbo via the ODBII Port? (I know its a J89 or something, but  can't remember the name at the moment 😉) I know this will be a lot of data, and I will need to figure out WHAT to track (which sensors come into turbo boost setting, etc) I believe the Warning is for a reading out of spec, and hope this will track down to a proximal cause of the turbo issue. I don't want to throw parts at it if I can help it.

I have taken it to the local shop and to Cummings, but they never find any evidence of what's causing the problem.

Thanks,

John

 

[Rikadoo]

We had one in our shop, that intermittently would blow black smoke an no powerwe had the turbo rebuilt 2 times an replaced 3 actuators, we had a “cummins” tech come help us an said to overlay a couple wires. Nothing we did made ANY difference, after a period of lenghty time we had it towed to cummins. They had it two weeks an decided the turbo was the problem, new turbo an 9k $$$ later its running like new. We couldnt charge one dime for anything we did, were gonna try to recoup our $$$ from the turbo rebuilder…

That said the lesson here is if YOU discover you have a bad turbo, just get a new one!

P.S. The rebuilder swore that we had something else wrong besides the turbo cause in his words, “were done looking at something that doesnt have a problem”

[BradHend]

That was the starting symptom of an exhaust manifold leak for me.  

[tmw188]

Curious how many miles is on your rig?

[MrAmbassador]

Question, how many mile do you have on your primary and secondary fuel filters? If there is not sufficient fuel to the injectors it feels exactly like the turbo is not working. If there is insufficient fuel to the injectors, the turbo cannot compress air. Wish you the best. 

[JohnC3]

My fuel filters were replaced in April and made no difference in the way this problem presents itself.

John

4 hours ago, MrAmbassador said:

Question, how many mile do you have on your primary and secondary fuel filters? If there is not sufficient fuel to the injectors it feels exactly like the turbo is not working. If there is insufficient fuel to the injectors, the turbo cannot compress air. Wish you the best. 

 

[timaz996]

Check all of your boots in your piping by flexing them and looking with bright light. What is your boost pressure when your power comes back?

[JohnC3]

22 hours ago, tmw188 said:

Curious how many miles is on your rig?

My 2008 Camelot has 140165 miles. I have put 35K on it since Sept 20. This issue started about 18 months ago and is slowly getting more prevalent.

John

14 hours ago, JohnC3 said:

My fuel filters were replaced in April and made no difference in the way this problem presents itself.

John

 

Sorry, in rereading my response I realized I didn't answer the question. There are about 5000 Miles on the filters, but they have been replaced maybe 3 times since this started and didn't seem to have an impact when replaced.

John

1 hour ago, timaz996 said:

Check all of your boots in your piping by flexing them and looking with bright light. What is your boost pressure when your power comes back?

When the power comes back the boost rises to over 30 (33-35).

John

[timaz996]

I doubt very much you could have a leak in the charger cooler or the boots with that kind of pressure. The only thing I can think of is a fuel issue and I’m not saying just the filters. Do you have any way of reading any codes?

[Gweedo]

Look into your Turbo Air Control Valve.  I found it for $359, lot of places had it for 7-800.  In a nutshell I had blk smoke, no power at take off, turbo kicked in at about 7-10 lbs of boost, blk smoke while cruising.   I discovered after waring it up to temp, shut it off for 10-minutes restart and worked normal.  Took it to cummins for computer update no diff.  Old time mechanic at cummins saw my issues a few times and suggested the control valve.  $1500 there but they didn't have it in stock, I found it for $359 and took a chance.  Solved my problem.  I don't if your issue can be solved by this but it's certainly worth looking into.  It took about 15-minutes to replace, sits on top.  Mine is a 400 ISL

[Frank McElroy]

On 7/18/2023 at 3:19 PM, JohnC3 said:

Hello Everyone, I have a problem I have seen here and could use some help trying to find a tool to find the real problem. I will (especially when going up/down hills have my warning light come on. This seems to frequently occur on a trip where turbo pressure drops to 0 for about 6 seconds when I am trying to accelerate. The Turbo recovers, I would describe it as it 'wakes up' after ~4 seconds and pressure builds and power returns. Couple of notes. Exhaust Brake use (or not use) has no impact on this. It happens either way. Occurrence is not frequent (Maybe every 6-8 hours of driving if there are hills, less frequent if flat). I have the Variable geometry Turbo that has an actuator to adjust the vane angle. The turbo will develop 33-35psi when fully engaged.

 

My first thought is the turbo itself seems ok, it will provide boost up to ~33psi as required (unless this issue is happening). SO I suspect the Actuator. But is thinking about this I am wondering if it could be the control signals (Sensor(s), connections, Control module, etc.). This is where I could use some help. I have had this checked more than once and no codes are thrown. The warning light comes on, but they cant see the cause for it. 

Is there a product that will let me record the sensor data and commands sent to the turbo via the ODBII Port? (I know its a J89 or something, but  can't remember the name at the moment 😉) I know this will be a lot of data, and I will need to figure out WHAT to track (which sensors come into turbo boost setting, etc) I believe the Warning is for a reading out of spec, and hope this will track down to a proximal cause of the turbo issue. I don't want to throw parts at it if I can help it.

I have taken it to the local shop and to Cummings, but they never find any evidence of what's causing the problem.

Thanks,

John

 

You have a sticking turbo actuator or a sticking turbo VGT mechanism.  When you go from coasting or engine brake mode to acceleration and the boost goes to zero, the turbo is getting stuck in the engine brake mode as the engine ECM cycles the turbo actuator to clean out the carbon buildup..  After a few seconds, you should get boost back IF you take your foot off the throttle.  If you hold your foot on the throttle for more than about 20 seconds, a check engine light will come on saying that the turbo actuator is not responding.  If that's the case, the turbo and electronic actuator needs to be replaced or rebuilt.

[Tom Cherry]

19 minutes ago, Frank McElroy said:

You have a sticking turbo actuator or a sticking turbo VGT mechanism.  When you go from coasting or engine brake mode to acceleration and the boost goes to zero, the turbo is getting stuck in the engine brake mode as the engine ECM cycles the turbo actuator to clean out the carbon buildup..  After a few seconds, you should get boost back IF you take your foot off the throttle.  If you hold your foot on the throttle for more than about 20 seconds, a check engine light will come on saying that the turbo actuator is not responding.  If that's the case, the turbo and electronic actuator needs to be replaced or rebuilt.

@JohnC3

Trust Frank.  He KNOWS.  I followed his saga through this when he diagnosed his own rig.  He has more “insight” (yes….a PUN) into the Cummins Insight software than maybe 80% of the “techs” and has helped more members than i can count analyze and find their problems by actually “reading and diagnosing” the problem from a Cummins’ dealer’s printout.  He has a long list of “that fixed it”.  I would PM him a d discuss offline….

He downloaded my ECM several years ago and I often discuss any issues or he explains how the data should be interpreted…I have also been on the periphery of him helping many others.

He had the same issue…and he will tell you offline how he resolved it…

Good Luck….