turbo/wastegate

[hate my 6.5]

Hello guy and gals
I drove my truck the other morning an it ran great. Drove it after lunch and not so great!
At idle it is loping like it has a big cam in it, but when i give it the pedal to get up to speed it will puff out thick thick black smoke then run good.
I am leaning toward something wrong with turbo system. I have good vacuum from the vac. pump, good vac. to the waste gate can. With engine off waste gate arm moves freely, with engine idling I can not move the arm at all, ( I am thinking that is correct).
There are no codes showing.
My question is if the wast gate is stuck open that would account for the bad idle and running better at higher RPM. Is that correct?

Thanks

 

[79jasper]

Imo, Wastegate will in no way affect how the engine runs.
Now if the turbo was seized, would be another story.
I would start simple. Check fuel pressure (maybe replace fuel and air filter)
Check the accelerator pedal position sensor assembly.

Sent from my SM-G892A using Tapatalk

 

[hate my 6.5]

Sorry I guess I should have said that both air and fuel filter has been replaced. How to I check the accelerator pedal?

 

[MrMarty51]

At idle, I think that there should be no boost, so the boost system should be out of the equation.

 

[hate my 6.5]

I believe the waste gate is closed at idle and opens at higher RPM to reduce over boosting, I might have it ass backwards tho.

 

[ak diesel driver]

Wastegate is closed until the ecm commands it to open with high boost being be the main factor. Regardless the turbo system won't affect idle, but it would affect acceleration. If it was stuck open you'd have lots of black smoke. I'd start by trying a different pmd, checking for air,(do you have the clear line on the IP?) And also grounds, these are in no particular order.

 

[MrMarty51]

I had a lot of problems with grounds and connectors in general. cleaned every terminal in every block at the back of the engine.
I`m still not sure if I have the problems figured out, I`ll know more tomorrow when i make the pilgrimage to church again. LOL

 

[hate my 6.5]

i did throw i different pmd on with no change yes i do have a clear line on the IP dont see any air all the ground have been cleaned.
It does smoke alot at idle

 

[ak diesel driver]

My guess would be IP if the other stuff doesn't fix it. Have you verified fuel pressure?

 

[Will L.]

Check fuel pressure and volume going to Ip.
Pull a sample from there and let it settle in a glass jar.

make sure there isnt a restriction in the air going into the engine, -dead mouse or something in there.

My thought is all that will come up no results and you are fighting injectors, but NEEDS to be ruled out first, after that...

While it is idling rough, crack injectors one at a time trying to ID which cylinders are misfiring- when you crack it, no change will occur. Note The other cylinders that are ok and casue a dip in rpm when cracking the nut. Then swap a non effected injector with one that does, see if the problem follows the injector. If it does, plan on set of injectors. If not, do a compression test.

If all 8 of the injectors cause a dip in rpm, jump straight to compression test.

 

[hate my 6.5]

Thank you I forgot to check the fuel pressure, it seemed ok when I bleed the air out after the fuel filter change.
I will try to do the injector test tomorrow. thanks for your help

 

[WarWagon]

How many miles on the injectors? At idle what kind of smoke: blue, White, black? White that hangs around or dissipates like steam?

Pop the oil fill cap off and start it: does it "chug" blowby like a burned through piston? When spinning on the starter is it zinging past a low compression hole?

The above advice is a good place to start as air is the #1 troubleshooting step to take. Clear line on the IP return. Grounds getting cleaned fixes a lot of problems often on here. @Will L. mentioned pulling a fuel sample: to the point you are looking for water settling out or it smelling like gasoline. Not the first or last time a tanker driver mixes up the tanks at the station's fill up time.

Beyond that we are looking for a popped head gasket maybe pushing coolant out, rocker button failed and valve no longer opening, or high mile injectors pissed a hole through a piston.

 

[Paveltolz]

If it was running fine in the morning and not so fine in the afternoon I'd question the fuel itself. Recent fill up at a different station than normal? Get a great price on fuel? Happened to me and until I could burn off the tank, change several filters plus get the remaining contaminated fuel diluted out, it ran like crap at idle, coughed on acceleration, belched more smoke until it got up to a little more speed etc. Did this for some time. If the accelerator pedal is bad, it should code. "Should" being the operative word.

 

[hate my 6.5]

Sorry it has been so long about for an update.
First off I want to thank everyone for their thought and ideas.
What I ended up finding was the problem was the optical sensor I replaced about a year ago loosened up and was moving around inside the IP. Once I put it back in place an made sure the bolt was TIGHT! It has been running amazing.

Thank again everyone!

 

[MrMarty51]

Thank You for replying with the fix. That could definitely help someone down the road, including Me.
Now,with that said, I hope You no longer "Hate My 6.5." LOL
In this case, it would be Your 6.5. LOL