RTH: GTurbo got lazy after highway drive, slow to build boost, lower boost levels than normal (1 Viewer)

[IanB]

Can you hear any exhaust leaks by chance? I blew out a manifold gasket once and it did some wonky stuff to performance. Just a thought. They usually give you some weird sounds associated with it though.

There is a noise/tone change compared to before I was having issues, sounds like a tractor is the best way I can describe it. It improved after shimming the wastegate actuator, so I'm pretty comfortable with the theory that it's exhaust leaking past the wastegate flap and bypassing the turbo. I have no muffler currently, so you get a real good idea when something has changed in that respect, lol.

 

[gerg]

Different exhaust sound before and after shiming sounds like the wastegate flapper was opening a bit. The turbine wheel soaks up a lot of the engine noise.

 

[Rock40]

Another thing to do would be adding a Hallman Boost Controller like this one: Hallman Pro Boost Controller Black

I swapped out to an "adjustable" Kinugawa wastegate actuator and went through a BUNCH of springs trying to make the damn thing create and hold boost No go. Once I installed the Hallman, all the problems were solved and I adjusted it to max out at 15 psi (stock CT26)

 

[gerg]

Inline controllers work great. Do you find the hallman gives you fine control? I've found with cheaper ones it's tuff to accurately set them, especially when you tighten them up.

 

[Rock40]

Yeah, the Hallman isn't cheap but you can really, really dial it in. The fine control is quite precise.

 

[IanB]

I have a Dawes MBC, seems to work pretty well. I don't believe it to be the source of my issues.

Dawes Devices Diesel MK II Hybrid Boost Controller

 

[Tapage]

Yeah, the Hallman isn't cheap but you can really, really dial it in. The fine control is quite precise.

I have a Hallman too .. it's not that fancy model but I was able to tune it very precisely to 24 PSI ..

 

[Imwhere]

Where is the sound coming from you mention? If disconnecting the wastegate doesn't produce uncontrollable boost there is something else wrong.
Exhaust manifold gasket? Exhaust manifold to turbo gasket?

Sounds like something has failed.

I was thinking perforated boost compensator diaphram but the change in sound makes me think an exhaust leak.

 

[DancesWithMutts]

Where is the sound coming from you mention? If disconnecting the wastegate doesn't produce uncontrollable boost there is something else wrong.
Exhaust manifold gasket? Exhaust manifold to turbo gasket?

Sounds like something has failed.

I was thinking perforated boost compensator diaphram but the change in sound makes me think an exhaust leak.

They prevailing theory at this point is that the wastegate spring has failed, so the wastegate is being pushed open by exhaust pressure, not by the actuator.

 

[IanB]

Where is the sound coming from you mention? If disconnecting the wastegate doesn't produce uncontrollable boost there is something else wrong.
Exhaust manifold gasket? Exhaust manifold to turbo gasket?

Sounds like something has failed.

I was thinking perforated boost compensator diaphram but the change in sound makes me think an exhaust leak.

There is an exhaust leak, at the wastegate flapper. The sound is coming from the exhaust (no muffler so you can hear even slight changes in tone and volume easily). My 1st thought was to check the fasteners and gaskets at the head/manifold and manifold/turbo connections, and they were fine. The wastegate spring would appear to have broken internally, it's not able to hold shut with any load on the engine, before I shimmed the wastegate it couldn't even hold at idle, yet it sealed shut with the engine off as I had the dump pipe off and inspected closely. Putting pressure to the actuator opened the flap as expected, it would snap shut when the pressure was relieved. With the actuator line removed it drove the same, except max boost was higher, but still very slow to build boost, and wouldn't hold boost at steady loads.

GTurbo is sending a replacement wastegate, but it won't be here in time for my trip. The Lexus is getting the nod this time around, which is pretty disappointing for me.

 

[Rock40]

@IanB, As an alternative to not taking it on your trip, you could install an oem wastegate actuator and run a MBC. I have 3 wastegates just lying around, I'll donate one if you're interested.

 

[IanB]

Well, as an alternative to not taking it on your trip, you could install an oem wastegate actuator and run an MBC. I have 3 wastegates just lying around, I'll donate one if you're interested.

I appreciate that, but I've run out of time on this.

6000km road trip with the family requires a vehicle I trust completely, and I have shifted my focus to getting the wife's truck ready at this point. I should have been spending the last few weeks getting the tune on the HDJ81 dialed in, and it just won't be at the point where I'm comfortable taking it. We leave next Friday and there's a lot of other stuff left to do to get ready.

 

[cody c]

Why not just tie wire it shut and see how it runs/run it?

 

[Tapage]

Why not just tie wire it shut and see how it runs/run it?

waste gate can be easily tested with a home compressor. If it's capable to make 20PSI at least with a gauge you can test how it is opening ..

 

[cody c]

Yeah, but I believe he said it seemed to work with a bicycle pump but the belief is that it is still the route of the problem.

Perhaps that engine can't handle the boost, but I'd say wiring it shut maybe a clamp on the line to it and see how it performs. If it runs decent the OP has moved forward in a diagnosis.

I have had similar issues with a leaky diaphragm on the boost compensator on my 6BT, but only after running for a while and it would leak diesel out of the atmosphere vent side of it

 

[cody c]

Sorry I should add, the leaky component flooded fuel on one side of the diaphragm not allowing it to move this cut off fuel essentially. It wasn't the diaphragm itself but a shaft seal near the diaphragm, a diagnosis for it is to pull the diaphragm and see if there is fuel pocketed under it.

 

[IanB]

Why not just tie wire it shut and see how it runs/run it?

Would you expect wiring it shut to be a whole lot different than disconnecting the reference line from the actuator?

It's going to take like 4 hours to pull the driveshaft and exhaust out, wire it shut, and put it back together, and even if it makes a difference it won't "fix" it. I need to drive it to work in the meantime, and I just don't have time anymore. I'll hold off until I have a new actuator and do it once at this point.

 

[cody c]

I think we must be talking about different things here.

I'm really not sure why you would have to pull a drive shaft or exhaust, and I have done this before in a few minutes. If your spring is faulty in the actuator the exhaust pressure can still deflect the diaphragm without the airline on it.

Anyways, I'm out on this, best of luck.

 

[IanB]

I think we must be talking about different things here.

I'm really not sure why you would have to pull a drive shaft or exhaust, and I have done this before in a few minutes. If your spring is faulty in the actuator the exhaust pressure can still deflect the diaphragm without the airline on it.

Anyways, I'm out on this, best of luck.

The wastegate flap is under the manifold, between the turbo and the block on the 1HD-T, you can only get at it from the bottom, and to get room to get at it to wire it up you'd need to remove a bunch of stuff.

Cummins has a top mount turbo, does it not? No big deal on that application to wire it shut.

I appreciate the suggestion all the same.

 

[Rock40]

Hey Ian, You CAN get to it from the bottom without removing anything but it is a complete PITA. I know this because the wastegate actuator rod blew off the fitting for the flapper on me once. I considered wiring it shut (I was 200 miles from home and towing) but I ended up rigging it together so I got about 1/2 the boost I normally did. To fix it right, I had to take things apart.

Anyway, wiring it shut doesn't have to look pretty but it certainly won't be anywhere near right. I'd also be concerned about having totally uncontrolled boost. With the flapper wired shut, the engine is going to build boost really quickly and then have no way to release it if it gets too high. Your foot (and a really close eye on the EGT gauge) is the only thing regulating boost and temps. Pretty risky if you ask me.