Engine/Transmission (1998.5 - 2002) Turbo barking to much

[M Evan]

Hi to everyone, hopefully somebody can help me I em little puzzled by my problem. I was on my way to Mexico, watch Baja 250 pulling my toybox trailer, around 10000 # loaded weight. I will try to explain my problem best I can. What happened after couple of hour driving that anytime I started to go little uphill and my speed lowered under 60 MPH my turbo started barking

( I think was the turbo ) and you can see on my boost gauge that needle started bounce up and down in difference about 5 PSI. Mostly happened when my boost gauge show 20 PSI, speed under 60 mph, 1600 RPM and transmission in overdrive, temperature of exhaust around 1000 and I hold steady on gas pedal. What I need to do is a switch from overdrive to stop this annoying barking. And look to me even that now turbo is a barking more often, even if I just let go on gas just a little bit and even on lower boost pressure. Before that I can make turbo bark, but only on pressure around 30 PSI and fast release of gas pedal. I em incline to say problem is the turbo, because I replace OEM one with a Pier 35 HX turbo about 3000 miles ego, but what could be wrong with it ? And was not a problem first 2500 miles which around 1000 was towing same trailer. If I look from compressor side, wheel spin freely and I don't have problem to pump 34 PSI like before. Could fueling have something to do with it ? I do run Power Edge on middle jumper and EDM 1. 5 injectors, for filter I use Scotty II system and I do have 4 inch exhaust. Any idea what is a problem ? Anything to help me to start fixing this problem will be appreciated very much.

m evan

 

[supeerman4422]

could it be the wastegate possibly?



-Tom

 

[Bob4x4]

It is normal for that turbo size,with that power and load. You can drive around it most the time with a slight change in driving habits



Bob

 

[M Evan]

could it be the wastegate possibly?



-Tom

My wastegate is disconnected. But I will pull turbo out and check that anyway. But if wastegate hold pressure 34 PSI, I don't think could leak on 20 PSI. But thanks for response, I will check everything.

mevan

 

[M Evan]

It is normal for that turbo size,with that power and load. You can drive around it most the time with a slight change in driving habits



Bob

You could be right, if I shift from overdrive sooner will be no problem. But because this problem don't started immediately when I installed Pier HX35,

somehow I think something is a bad and make me unconfortable to drive like that. Don't like to think that next time on my trip something will give up and left me stranded in middle of nowhere. But thanks for your response.

mevan

 

[Bob4x4]

You could be right, if I shift from overdrive sooner will be no problem. But because this problem don't started immediately when I installed Pier HX35,

somehow I think something is a bad and make me unconfortable to drive like that. Don't like to think that next time on my trip something will give up and left me stranded in middle of nowhere. But thanks for your response.

mevan

Give PDR a call they will releive your fears



Bob

 

[rweis]

Would the "Turbo Quiet" from BD have any possibilities here?



Bob Weis

 

[M Evan]

Would the "Turbo Quiet" from BD have any possibilities here?



Bob Weis

I don;t have any idea what is it. Can you please send me the link on this product.

THX mevan

 

[Bob4x4]

I don;t have any idea what is it. Can you please send me the link on this product.

THX mevan

A bit pricey but here you go



http://www.bd-power.com/ram/product.php?pn=BD TurboGuard&tt=ram



Bob

 

[M Evan]

A bit pricey but here you go



http://www.bd-power.com/ram/product.php?pn=BD TurboGuard&tt=ram



Bob

Thanks this could work, but you right it's bit pricey device. But if work how they say will probably solve the problem.

mevan

 

[JBlomenberg]

Re: Barking Turbo

It sounds like your turbo is going into surge, where the compressor can't make the required boost at the airflow you are running at. This usually happens at lower RPM's and high loads, which sounds like what you are explaining. Your larger turbo is sized to give you good power and airflow on the top end, but just can't move the air effectively on the bottom end, especially with the wastegate disconnected. That's also why your EGT's are so high. If you had a compressor map to look at, you'd be running to the left of the map. Shifting out of O/D increases engine speed, and move the engine airflow (breathing line) to the right on the map, and back towards the heart. This is a classic turbo matching issue that engineers like me get to deal with all the time on diesels. I'd bet the wastegate will fix it. If you continue to run there, you could have premature turbo failure. Either the thrust bearings will give out, or the nut will back off and you'll swallow it. Mega $$$ if that happens.



Good luck!



Justin

 

[moparguy]

M Evan, you're dealing with the same problem I have with the HTT 2 hybrid kit I installed in my HX35. After 3 years, I've come to believe it's OK to live with the problem, just adjust your driving style so it doesn't surge. As you've learned, a few more rpm is all that's required.



My turbo only surges above 5,000 feet or so. Don't quite understand that, but a quicker downshift makes it go away.



Good luck, RR

 

[rweis]

I have a thread on the BD site asking about exactely how the Turbo Guard works.



Apparently there are two different flavors of turbo bark:



A - 1 during acceleration which has its own set of parameters

B - 1 during rapid throttle release which has its own set of parameters



Mine is during the 3 -> 4 shift of the ETC transmission which is sort of like #2. BUT if the TurboGuard control is based on APPS input I do not think it will function in my case because the APPS is in the same position, but the 3 -> 4 shift changes the engine rpm and not the APPS.



However if the turbo bark is like WOT then idle go pedal, then the APPS is at an idle position and it might work like flavor B above.



The thread on the BD board talks about the A case of bark during acceleration.



Bob Weis

 

[JBlomenberg]

Barking is Bad

There seems to be a lot of good discussion going on about this problem. The info on turbo surge during cases where the engine is loaded and then the throttle is shut quickly (or in this case, we cut fueling very quickly since the diesel doesn't have a throttle), is accurate, and is very tough to prevent, especially in engines like our beloved 5. 9, which has air-to-air aftercooling. The build up of pressure in the cooler, manifold, and associated plumbing ahs to go somewhere, and sometimes it goes back out the compressor. The pop-off valve can fix this by relieving intake pressure temporarily during the event.



The surge that is taking place under normal driving conditions is difficult, if not impossible to correct if it truley is surge. A pop-off valve will not fix this since it is not an issue of too much pressure for the manifold, but rather a turbo phenomenon. Again, it happens when the engine is trying to consume more air than the turbo can provide at that speed. It is magnified at altitude since the air is less dense. It takes even more CFM (volumetric flow) to get to the same mass flow of air that is needed for combustion. This takes the engine off the compressor map. Being off the compressor map means that it is physically impossible for the compressor to move the required amount of air at the pressure level required to get it into the engine. The quicker down shift corrects the problem by increasing engine speed, and thus increases the air flow and moves back onto the compressor map.



The attached file is a sample compressor map. Along the x-axis is air flow, and on the y-axis is compressor out pressure. THIS IS NOT A REAL MAP FROM THE B5. 9, but is a stylized map that is representative of the problem. The pink line is the 1600 rpm case. As boost gets higher (corresponding to increasing engine load), the line eventually goes outside of the map. The second point on that line is mentioning what happens at altitude. The blue line is an example of what would happen when you down shift, and the red is an example of how it might be sized for maximum power at higher rpm. You can see that both of them are near the middle of the map, where the compressor is more efficient.



This is a little long winded, but I want to make sure you guys don't spend money on something that won't fix your problem. I didn't read the thread on the BD website, which probably gets into more detail as well.

 

[NoSeeUm]

Just a little related information, but not relation to fixing your problem.



Turbine style compressors can get into two conditions that I know of that are bad.



Surge



This is when the you back flow through the compressor. As an example, when you bark your turbo. This is cause by reversed direction air flow from the high pressure side of the compressor to the low pressure side. Immediately followed by, the return to the normal flow direction of low pressure to high pressure.



It can also occur on multi-stage compressors (turbine engines) on ramp up. The high pressure stages build pressure faster than the lower pressure stages. High pressure inter-stage bleed valves open during start-up to normalize this. (It is also to prevent snuffing out the flames at the lower RPM's)



Stall



Compressor blades, in many respects, are aerodynamic. Much like an aircraft wing. Air must more or less adhere to the surface of the blade. It is this loss of adherence that causes stall. Just like for an aircraft wing.



For the nuts and bolts of it. This is means that for a given compressor wheel RPM air must be traveling linearly through the compressor with in a given speed range to maintain the correct aerodynamics of the blades. AKA the compressor map.



Surge and Stall



The bad part is that you really can't have one with out having the other in some form. None of it is good. Surge causes stall and vice versa.



This is probably an extreme example so take this idea with a grain of salt. To illustrate the mechanical stress that the turbo is feeling. Imagine taking out your boat that has an outboard motor. Get going at a fairly good clip and then take the steering wheel and whip it all the way right and then all the way left very rapidly a few times. The prop will bite the water then spin freely at high RPM then bite the water again. The engine alternates between zero load and maximum load very rapidly. Engine RPM is very low under heavy load, then instantly over revving, and then back to very low again.



Not related, but multi-stage compressors can suffer from surge and stall at an inter-stage level. As well as the entire compressor globally.



Probably way to much information anyways.



Jim

 

[JBlomenberg]

Jim-

Very good info! I'm glad that there are others out there that understand this stuff, too. I work in performance development for Cummins on the High Horsepower engines (750hp +) and have to work through turbo matching issues all the time. Fun Stuff!



Justin