[cumminsfan88]

Okay so hopefully I can get some input from yall on here. When my 05 shifts into overdrive the turbo will bark/surge. If I turn my programmer from economy to performance it will surge/bark while shifting into third. I have to let off the pedal while the truck shifts into overdrive to stop the bark. Do I have a turbo problem or a tranny problem? I built it myself last spring with a list of goodies and followed the instructions on disassembly and reassembly as far as all gaping with the flat feeler and micing and checking the valve body with compressed air.

 

[cumminsfan88]

Nobody has any input?

 

[IndyTruck]

your truck shouldnt be surging when shifting unless your romping on it and letting off fast

 

[cumminsfan88]

I do not romp on it and definitely dont romp and let off. But I just am curious if anyone has had the same thing or close and know if it is a pressure issue in the trans or if the converter is locking up to soon or to late ( the truck hits overdrive at 55-58 with 3.73 gears and 35's). Or if there is something I can't see or don't know about in the turbo. Turbo has very little shaft play. I haven't pulled the turbo off yet to actually examine it.

 

[waywardtravel]

There is two different scenarios that create the bark.
Romping on it and letting off too fast or A solid shift.
You have to learn to drive around both. It's not as common to have a 3rd gear bark but the 4th or OD TC lock at 50mph will do it on most built transmissions. Try getting on it way harder and the bark might go away because of the later in RPM shift, Or let off early like your doing.
If your getting it in third you have a very strong holding trans and torque converter and or your TC is locked during the shift.

 

[cumminsfan88]

Okay. So when I get on it hard it still barks but not as bad. And then it didn't bark a few shifts after that. So is having a torque converter locked during shifting a bad thing?

 

[waywardtravel]

It should not be locked going into 3rd. ON an 04.5 it will lock with tow/haul on in 3rd at 50mph and not go into O/D. I'm pretty sure your tow/haul does not lock out O/D though.

Mine will lock the second it shifts into O/D under most different load ranges.
Light throttle it doesn't and heavy it doesn't.

Barking is bad for the turbo and will shorten it's life for sure.

The cure is

 

[NeMachinist]

After I put in a shift kit and some other stuff in the trans I had a serious problem with turbo bark.
This was only in od converter lock up, and it would bark 3-4 times if I didn't pay close attention.
I swaped my he341 for the 351, like you have, and mine won't bark at all...I have a stock torque converter though.
So maybe there could be a turbo that would be less prone to bark. Expensive fix, just a thought.


Sent from AutoGuide.com Free App

 

[cerberusiam]

They will bark, not surge, into 3rd and OD if you have the TC locked. They will bark in 3rd or OD on TC lockup if the conditions are right. They wil generally bark less if you keep your foot in the throttle on the shifts.

A solid shift and firm TC lockup will bark them even with stock fueling. Just the nature of a big compressor wheel and small housing.

As soon asr your rpms drop on a shift point of TC lockup the fueling is dropped accordingly so that drops the exhaust flow and it won't support the boost the compressor is making. The more fuel you add the worse it gets.

Mine has done this for over 150k and the HE351 hasn't given up yet. Now tomorrow it will blow up the first time it happens. :rof The turbo is pretty tough and even thouhg the compressor stall (bark) is not a good thing it is not instant death. Stalling the compressor when it is at +10l rpms, that is a different story. They really don't like that at all.

 

[cumminsfan88]

Okay. Well im glad to know this is a normal thing. And it probably doesn't help that the truck has been chiped since off the lot and 100 horse injectors since 100k and she now has 230k and the turbo is original. So if I were to upgrade turbos to say compounds ( really want a stocker/s475) would the turbos still bark and would it be worse?

 

[cumminsfan88]

Also I understand it barks because the rpm drops when it shifts (and it drops almost as fast as my dads vett) but could the problem be to high of line pressure or say I built the overdrive section to tight and it will cause some kind of failure?

 

[cerberusiam]

Nope, nothing in the trans working right will cause a turbo bark. That is purely loss of exhaust flow when rpms drop. On compound swhere the big turbo is feeding the samall one it should less usceptible to that kind of problem whne fuel is cut abruptly, more pieces in there to buffer the effect.

 

[cumminsfan88]

Okay. So basically when I get the cash upgrade. That is a no brainer!!!! And drive easy to prevent or lessen the bark like I have been doing. And as far as the shift into o/d could I have built it to tight and it shift to hard?

 

[waywardtravel]

No it's very common on the TC OD lock on any built trans. It simply grabs harder so we can go faster and or get a more solid connection.

 

[cerberusiam]

Shift to OD is the worst offender becasue of the rpm drop. It is a big jump from 1:1 to 1:.69 on the ratios. The shift is actually not the problem, it is the almost immediate lockup after the shift that cause the bark. If you could slow down the lockup apply it would elminate the bark.

The shift-lock just drops exhaust flow too much and the bigger the injectors and the hgher the SW setting sthe worse it gets.

 

[cumminsfan88]

So it wont snap a shaft or anything like that in the turbo? I know it is possible just want to make sure im not killing my turbo to early.