Wits End Turbo Owners (5 Viewers)

Joined
Feb 10, 2017
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Seattle
It seems that several owners of this kit are not seeing the 7 PSI boost that myself and others are. I like to keep things simple when troubleshooting, leaving the really complex failure modes until the simple stuff is ruled out.

The simplest explanation is that the boost gauge is reading incorrectly. I bought a cheep manual gauge two weeks ago to verify the boost on my rig, and it correlates to what the 14 in one gauge is telling me. 7+ PSI max (saw 7.6 PSI under full acceleration over the weekend, for just a second)

The next simple explanation is a boost leak. The compressor housing to the center housing is a possible leak path. There are only four connections after the turbo before the TB. Then you have the TB gasket to the upper intake, then the upper intake to the lower intake, then the lower intake to the head. There are numerous ports in those assemblies to look at, including the EGR, brake booster (should have a check valve from kit), and the PCV valve . The PCV should act like a check valve under boost. It could possibly be leaking at higher boost levels and dumping the boost into the valve cover? Then it flows back to the intake side of the turbo?

(Side question, with a large boost leak, isn't the turbo being turned at higher RPM's due to the wastegate not opening, as it is not seeing a pressure signal to open? Is over speeding the turbo a risk with a boost leak?)

Another simple explanation is that the wastegate is opening too soon. You verified you have the correct springs. The next step would be to pressurize the wastegate manually and verify that it is opening at the correct pressure. Probably not likely that the correct springs are out of spec, but, maybe?

On the exhaust side of the turbo, as you looked into, a restriction could be putting to much backpressure on the turbo, causing lower flow, lower turbo RPM's and less boost. You could also have a large exhaust leak, but, I think you would notice that.

Hope this helps,

Mike

I regularly am seeing 6.1psi, with the occasional blip to 7.
I was seeing higher consistent boost levels loaded down pulling grades.
If i'm empty and flooring it usually only see 5 or so since the motor isn't under enough load to boost to 7 before shifting.

This can be a lot of things.
is the truck driving normally turbo aside? Throttle position sensor functioning properly and adjusted correctly?
Holding gears properly? Trans kickdown adjusted properly?

I replaced my upper intake manifold gasket and TB gasket last weekend since i was seeing some signs of seepage at the joint of the upper and lower intake manifold and a slightly high idle.
Afterwards I wasn't seeing as high of boost and truck wasn't downshifting well or building as much boost. Pretty sure i need to tension the trans kickdown up a bit to get back to where it was.
Think of simple stuff.
Rule out the gauge first, and verify that it actually reads 0 at ambient for your elevation.
Check for boost/vacuum leaks between compressor housing and block. All gaskets appear leak free?
Do some reading about diagnosing turbo systems online, pretty basic across all turbo vehicles.
 
Joined
Oct 28, 2015
Messages
488
Location
CA
For my system i'm getting 5.3 on max boost typically. Verified against 2 boost gauges I have installed on my truck.
PLX Devices SM Pro digital
TRD OEM (made by Autometer) manual

PLX gives me a history graph and shows my max boost.
 
Joined
Oct 9, 2018
Messages
94
Location
Santa Rosa, CA
Thanks Mike, good writeup.

I was thinking of getting a Blue spring from eBay and combine that with the Green spring to see if I get past 5psi before I start looking for leaks and such. This will be a TEMP solution as I don't want to lean out the engine due to lack of fueling. Just a thought for now...
The boost goes pretty quick from 5 PSI to max under hard throttle. I would be careful in testing with that setup. You might try putting pressure on the wastegate to see if it actuates at 5 PSI or 7 PSI. Safer that way.
 
Joined
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Messages
94
Location
Santa Rosa, CA
I regularly am seeing 6.1psi, with the occasional blip to 7.
I was seeing higher consistent boost levels loaded down pulling grades.
If i'm empty and flooring it usually only see 5 or so since the motor isn't under enough load to boost to 7 before shifting.

This can be a lot of things.
is the truck driving normally turbo aside? Throttle position sensor functioning properly and adjusted correctly?
Holding gears properly? Trans kickdown adjusted properly?

I replaced my upper intake manifold gasket and TB gasket last weekend since i was seeing some signs of seepage at the joint of the upper and lower intake manifold and a slightly high idle.
Afterwards I wasn't seeing as high of boost and truck wasn't downshifting well or building as much boost. Pretty sure i need to tension the trans kickdown up a bit to get back to where it was.
Think of simple stuff.
Rule out the gauge first, and verify that it actually reads 0 at ambient for your elevation.
Check for boost/vacuum leaks between compressor housing and block. All gaskets appear leak free?
Do some reading about diagnosing turbo systems online, pretty basic across all turbo vehicles.
Good point on the trans kickdown. I have a shift kit in my trans and I have the trans shift linkage set to downshift early. Carries more RPM's, which means more flow through the exhaust.
 

Pierce

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San Antonio
I’m just a lowly supercharger guy but is air temperature being taken into account with your varying boost pressures?

During summer, 100+ degrees, my boost is usually around 5 psi. Now with temps between 55 and 70 degrees I see my boost averaging 6-7 psi with occasional trips up to 9 psi. Cooler the temperatures, higher the psi.

3rd gen Magnuson Supercharger, 5th gen rotors, 3” pulley (standard is 3.25”) for reference.

My point is that all of your turbos may be operating optimally for your conditions. My 5 psi in S. Texas may be 7 psi on the same day and time in Washington St where the temps are 30-40 degrees cooler.

Just theorizing:meh:
 
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Joined
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I’m just a lowly supercharger guy but is air temperature being taken into account with your varying boost pressures?

During summer, 100+ degrees, my boost is usually around 5 psi. Now with temps between 55 and 70 degrees I see my boost averaging 6-7 psi with occasional trips up to 9 psi. Cooler the temperatures, higher the psi.

3rd gen Magnuson Supercharger, 5th gen rotors, 3” pulley (standard is 3.25”) for reference.

My point is that all of your turbos may be operating optimally for your conditions. My 5 psi in S. Texas may be 7 psi on the same day and time in Washington St where the temps are 30-40 degrees cooler.

Just theorizing:meh:
I believe the turbo's with the wastegate operate independently of temperature. The wastegate receives a pressure reference from the boost side of the turbo. The springs in the wastegate are selected to keep the pressure in the manifold at a desired boost level by moving more or less exhaust around the turbine on the turbo.
 

Pierce

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Hahaha, thanks. I thought I understood it until now! :flipoff2: Or maybe I just didn’t care because a geographical feature where I live is a highway overpass. It gets murky when it gets into the efficiency/power/psi nonsense where you may be making more power with less PSI if it’s more efficient. I just turn my brain off at that point.
 

alia176

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Tijeras, NM
So, I was soaking in the hot tub last night and thinking about the P0171 code ;) This happens when the air/fuel ratio is too lean, meaning more air than fuel. Seems like we've been concentrating on possible pressurized air leakage around the intake air path but would it be worth steering our discussion toward fuel delivery? Before the turbo went on, I replaced the FPR, fuel filter and the fuel pump sock but the fuel pump is original from 1996. Is there a chance that this fuel pump isn't able to deliver fuel when I'm on boost? This is a two speed fuel pump so is it worth bypassing the fuel pump resistor and have it run on high speed mode all the time? How about capping off the FPR to deliver max fuel press to the fuel rail? I'm just thinking out loud here so feel free to blow holes in my suggestions!
 

landtank

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Groveland MA
The P0171 code is determined during closed loop. I don’t think that has changed since adding boost
 
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Joined
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Joey is going to roll his eyes at this...

I have been doing some testing with the turbo kit, WOT runs, looking for a lean condition at max boost. The Lambda never got even close to 1 during any of my testing, staying in the .6 to .7 range at max boost (7.8 PSI was the highest I saw).

So, I swapped out the wastegate springs to bump up the boost the next step. The kit comes with green and red springs in the wastegate for a set point of 7.25 PSI. I swapped out the red and put in a blue for a set point of 8.7 PSI. Did a bunch of testing easing into the runs until I am now doing hard WOT runs and the max boost I have seen is in the picture below with the 0.80 Lambda on the wideband A/F. Still rich even at 8.7 PSI.

The rig weighs in at 6800 lbs with all of the gear I have hung on it. It pulls hard at 8.7 PSI.

Fun stuff. Now watch me melt a valve or a piston....

Edit: New fuel pressure regulator, new fuel pump, serviced injectors, new O2 sensors.

Mike

IMG_3954[1].JPG
 
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Joined
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Wide open isn’t the only condition you have to worry about with the turbo, the concern is part throttle, low boost conditions. The kit was made to ensure it is safe in all conditions. Any changes from this kit removes any liability from anyone associated with the kit. You are on your own.





Joey is going to roll his eyes at this...

I have been doing some testing with the turbo kit, WOT runs, looking for a lean condition at max boost. The Lambda never got even close to 1 during any of my testing, staying in the .6 to .7 range at max boost (7.8 PSI was the highest I saw).

So, I swapped out the wastegate springs to bump up the boost the next step. The kit comes with green and red springs in the wastegate for a set point of 7.25 PSI. I swapped out the red and put in a blue for a set point of 8.7 PSI. Did a bunch of testing easing into the runs until I am now doing hard WOT runs and the max boost I have seen is in the picture below with the 0.80 Lambda on the wideband A/F. Still rich even at 8.7 PSI.

The rig weighs in at 6800 lbs with all of the gear I have hung on it. It pulls hard at 8.7 PSI.

Fun stuff. Now watch me melt a valve or a piston....

Mike

View attachment 2505946
 
Joined
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Messages
94
Location
Santa Rosa, CA
Wide open isn’t the only condition you have to worry about with the turbo, the concern is part throttle, low boost conditions. The kit was made to ensure it is safe in all conditions. Any changes from this kit removes any liability from anyone associated with the kit. You are on your own.
No problem on liability, I own anything that happens to it. I have been recording the data as I drive around and the only time I get a Lambda over 1 on the wideband A/F is at idle (1.04 to 1.1). I have a vacuum leak somewhere. Today I replaced the EGR valve, as it was not sealing all the way. Will be testing to see if that helped at idle.

But man, this engine sure likes boost....

Thanks,

Mike
 

NLXTACY

Wits' End
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No problem on liability, I own anything that happens to it. I have been recording the data as I drive around and the only time I get a Lambda over 1 on the wideband A/F is at idle (1.04 to 1.1). I have a vacuum leak somewhere. Today I replaced the EGR valve, as it was not sealing all the way. Will be testing to see if that helped at idle.

But man, this engine sure likes boost....

Thanks,

Mike

good to hear. And yes 7.25 was chosen for exactly the reason @scottryana stated.

The other aspect is the condition of your motor, vacuum, fuel system, etc will not match others so trying to get everyone’s engine to see what you see gets a lot more difficult than seeing 7.25.
 

alia176

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Joined
Aug 21, 2003
Messages
12,800
Location
Tijeras, NM
Joey is going to roll his eyes at this...

I have been doing some testing with the turbo kit, WOT runs, looking for a lean condition at max boost. The Lambda never got even close to 1 during any of my testing, staying in the .6 to .7 range at max boost (7.8 PSI was the highest I saw).

So, I swapped out the wastegate springs to bump up the boost the next step. The kit comes with green and red springs in the wastegate for a set point of 7.25 PSI. I swapped out the red and put in a blue for a set point of 8.7 PSI. Did a bunch of testing easing into the runs until I am now doing hard WOT runs and the max boost I have seen is in the picture below with the 0.80 Lambda on the wideband A/F. Still rich even at 8.7 PSI.

The rig weighs in at 6800 lbs with all of the gear I have hung on it. It pulls hard at 8.7 PSI.

Fun stuff. Now watch me melt a valve or a piston....

Edit: New fuel pressure regulator, new fuel pump, serviced injectors, new O2 sensors.

Mike


So, I did the same thing using Blue springs trying to figure out why i wasn't able to go past 5psi but now I'm going past 5 psi. I don't have a digital gauge so don't know the exact psi i'm achieving. At least now, she is on boost a little earlier and is able to climb hills with a little more authority. Still, I haven't gone on any sustained, long/steep hills to see if I can stay out of second gear but I'm hopeful.

Again, I'm doing this to understand what was preventing the engine from going to 7psi using the original springs provided with the kit. Unfortunately, I don't really know the cause, yet. I'm very cautious with this change as it can have dire consequences.
 

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