1G Car not building any boost

[Mikey_Dsm]

The issue I got going on right now is the car isn’t building any boost but I hear it spooling. I have a MBC, and a boost gauge that came with the car when I bought it. Every thing worked fine before, until I rebuilt the engine and recently reinstalled it.

I took it for a drive and noticed it isn’t building any boost. so I did the boost leak test on the car and didn’t find any leaks on the couplers or j-pipe connected to the turbo.
With that done I took it for another drive and paid attention to my gauge and as it tried to make a pull it gets close to 0 but climbs back down to 10inHg and doesn’t make any boost.

Car has new gaskets all around and the vacuum lines are all connected properly. But it still seems to have a big leak somewhere. Another reason I know it’s a leak is when I brake hard the car stalls when driving.

I’m running a rebuilt 14b with a 13g actuator arm. I did do some research and it could be the arm so I will test that tomorrow. The weather where I live makes it a little hard to get the chance to work on the car but I’ll continue to chase down what it could be.

Any pointers would help

 

[DSMPT]

Assuming you have zero boost leak, I would check for the possibility below.

- The boost gauge is broken or not installed properly. (Actually you have boost)
- The actuator rod. Maybe it is not installed properly, maybe popped out from flapper causing exhaust leak, no exhaust back pressure, etc.
- Dead turbo.
- Incorrect mechanical timing.

 

[Mikey_Dsm]

So I tested the actuator rod and it works. And the flapper moves freely and the rod isn’t dislodged from it. The boost gauge is connected from the bov line to manifold, could that be a issue?

I’m know my timing is correct, but what could cause the mechanical timing to incorrect? And how could I test the turbo to make sure it isn’t dead?

 

[DSMPT]

And the flapper moves freely and the rod isn’t dislodged from it.

Did you make sure if the flapper is fully closed after you attache the actuator rod?

I’m know my timing is correct, but what could cause the mechanical timing to incorrect?

Valve timing affect the turbo spool.

And how could I test the turbo to make sure it isn’t dead?

Just remove the intake pipe from the turbo and check for the shaft play and if the wheel contacts with housing or not. When the turbo is dead but if still the shaft is spinning you can hear it but it wouldn't build boost. When the turbo is dead and the shaft is getting stuck, you would start to have an experience of engine stall more since you technically have a huge restriction in intake and exhaust.

when I brake hard the car stalls when driving.

This made me think about dead turbo or/and wrong timing. It just came up to mind, nothing is for sure though.

 

[RamenPride]

I’m know my timing is correct, but what could cause the mechanical timing to incorrect?

Timing belt may have jumped and skipped a tooth

 

[Mikey_Dsm]

Timing belt may have jumped and skipped a tooth

I’ll have to double check timing then when I get a chance.

Just remove the intake pipe from the turbo and check for the shaft play and if the wheel contacts with housing or not. When the turbo is dead but if still the shaft is spinning you can hear it but it wouldn't build boost. When the turbo is dead and the shaft is getting stuck, you would start to have an experience of engine stall more since you technically have a huge restriction in intake and exhaust.

Minimal shaft play, but it does spin freely and I do hear it when I drive. But doesn’t make boost.

Did you make sure if the flapper is fully closed after you attache the actuator rod?

flapper is fully closed when the rod is connected, and the actuator works.

 

[pauleyman]

Did you check the turbo to manifold bolts and see if they are loose?

 

[chrisman287]

Is your turbo missing the o-ring between the compressor housing and center?

 

[Mikey_Dsm]

Did you check the turbo to manifold bolts and see if they are loose?

Yes, Those are nice and tight

Is your turbo missing the o-ring between the compressor housing and center?

I’d have to take off the turbo to inspect it but I know that it does in fact have it

 

[pauleyman]

Yes, Those are nice and tight

I’d have to take off the turbo to inspect it but I know that it does in fact have it

Which car is this? Have you made any changes? Are you running a ported manifold and turbine housing with the fire ring?

 

[Mikey_Dsm]

Which car is this? Have you made any changes? Are you running a ported manifold and turbine housing with the fire ring?

It’s for the Plymouth laser. Only changes I’ve made are to the manifold. I’m running a forced performance one. And I don’t believe it has the fire ring.

 

[chrisman287]

I’d have to take off the turbo to inspect it but I know that it does in fact have it

If you blt spray the back of the compressor housing

 

[dwb]

It takes a pretty big boost leak to not build *any* boost. If that were the case, the car would barely run (assuming MAF car). Same if the mechanical timing was off. To me it sounds like an issue on the hot side of the turbo. Wastegate flapper missing/held open or missing/damaged turbine wheel.

 

[pauleyman]

It’s for the Plymouth laser. Only changes I’ve made are to the manifold. I’m running a forced performance one. And I don’t believe it has the fire ring.

If it does have a ring I've seen those get hot, distort, and end up in the throat of the turbine housing. I've also seen the flapper arm not sit flush which means the flapper isn't over the hole. The arm should sit right up against the housing.

 

[Mikey_Dsm]

If you blt spray the back of the compressor housing

I did and didn’t see any leakage

I've also seen the flapper arm not sit flush which means the flapper isn't over the hole. The arm should sit right up against the housing.

the flapper does sit against the against the housing when I was inspecting it before install.

It takes a pretty big boost leak to not build *any* boost. If that were the case, the car would barely run (assuming MAF car). Same if the mechanical timing was off. To me it sounds like an issue on the hot side of the turbo. Wastegate flapper missing/held open or missing/damaged turbine wheel.

it is a maf car, I plan to inspect mechanical timing here soon in a couple days to make sure it didn’t skip a tooth

If I have to I will take off the turbo and disassemble it and to make sure it’s all in good working order

 

[DSMPT]

The boost gauge is connected from the bov line to manifold, could that be a issue?

Did you check if the boost gauge itself is not broken? Is this a mechanical gauge? And please provide some pics how you connect the boost gauge and BOV and MBC.

Also how is the idle? Is it stable?

 

[Mikey_Dsm]

Did you check if the boost gauge itself is not broken? Is this a mechanical gauge? And please provide some pics how you connect the boost gauge and BOV and MBC.

Also how is the idle? Is it stable?

Mechanical srt4 boost gauge that reads up to 20psi. Was already wired and set up when I bought the car.

Changed out the MBC to a different one to see if that fixed the issue but it didn’t. the way it’s connected is correct.

The purple line that’s highlighted is T’d to the boost gauge.

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[DSMPT]

Mechanical srt4 boost gauge that reads up to 20psi. Was already wired and set up when I bought the car.

Changed out the MBC to a different one to see if that fixed the issue but it didn’t. the way it’s connected is correct.

The purple line that’s highlighted is T’d to the boost gauge.

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Just in case, let me ask again, did you confirm that the gauge is not broken or reading correctly?

it tried to make a pull it gets close to 0 but climbs back down to 10inHg and doesn’t make any boost.

I am asking because of what you described, this ^.

If I understood well according to what you described, you did a pull (WOT) to see if you have the boost, and then you are seeing only 10in/Hg of vacuum after gas pedal off, this sounds very weird to me. You should have had much more vacuum. That's why I keep asking about the gauge and the valve timing as the first things came up to mind were the gauge is not reading correctly for some reason or the valve timing is wrong (actually you have boost or slow spool).
If a healthy turbo dsm is building absolutely zero boost due to massive boost leak or exhaust leak, the car would respond obviously slower with no power than as it should, you even didn't need to check the gauge. You could have felt it.

One thing, please don't guesstimate. Physically check everything agin by yourself, even you think it's not necessary.

 

[Mikey_Dsm]

If I understood well according to what you described, you did a pull (WOT) to see if you have the boost, and then you are seeing only 10in/Hg of vacuum after gas pedal off, this sounds very weird to me. You should have had much more vacuum.

Under WOT trying to hit boost I can feel the spooling of the turbo and see the boost gauge go up to 0 and then go down to 10inHg while having my foot on the pedal. But when I let my foot off the pedal it drops down close to 20inHg. Almost feels like driving a n/a car, it doesn’t bog or anything it’s very steady all the way through just doesn’t build power like it should.

One thing, please don't guesstimate. Physically check everything agin by yourself, even you think it's not necessary.

You’re right, I do plan to go over all vacuum lines to everything including the gauge and double check timing to make sure it didn’t skip a tooth and another do another blt before removing the turbo as a last resort to inspect it properly.

Will update what I find as I need to replace my headgasket before any further driving

Just in case, let me ask again, did you confirm that the gauge is not broken or reading correctly?

Yes the gauge works as needed and isn’t broken

 

[pauleyman]

Under WOT trying to hit boost I can feel the spooling of the turbo and see the boost gauge go up to 0 and then go down to 10inHg while having my foot on the pedal. But when I let my foot off the pedal it drops down close to 20inHg. Almost feels like driving a n/a car, it doesn’t bog or anything it’s very steady all the way through just doesn’t build power like it should.



You’re right, I do plan to go over all vacuum lines to everything including the gauge and double check timing to make sure it didn’t skip a tooth and another do another blt before removing the turbo as a last resort to inspect it properly.

Will update what I find as I need to replace my headgasket before any further driving

Replace head gasket? Elaborate please.
As far as boost goes, if you've elimated gauge and leaks the only thing left is turbo and timing. Even timing shouldn't do it in my opinion as it would still build boost. If timing were off that bad car wouldn't idle or even run or would've bent a valve.
The last possible thing would be is if you have an exhaust restriction so large the turbo can't function. Only time I ever saw this was on a super cheap downpipe and the flex section collapsed internally and was about the size of a golf ball. You could rule out exhaust if you just drop the downpipe and go for a short drive. Gotta wonder why we're discussing this if you think the car has a bad head gasket.

 

[Anfurnyy]

Mechanical srt4 boost gauge that reads up to 20psi. Was already wired and set up when I bought the car.

Changed out the MBC to a different one to see if that fixed the issue but it didn’t. the way it’s connected is correct.

The purple line that’s highlighted is T’d to the boost gauge.

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Isnt that purple line the PCV check valve?

 

[19Eclipse90]

How did you verify the wastegate actuator is fully closing the flapper?

Seems this was breezed over, even though you pointed out using a 13g actuator on a 14b turbo in your original post. I’ve never had a 13g so I can’t speak to compatibility, but it is something to check considering different part numbers.

Isnt that purple line the PCV check valve?

PCV is on the valve cover. It is not shown on that diagram.

 

[Mikey_Dsm]

Replace head gasket? Elaborate please.

as I try and figure out why it isn’t building any boost I check to make sure all the components are in working order when I take it for test drives to see if it was fixed as I’m still breaking in the engine. and found out recently the head gasket isn’t sealing properly and don’t want to risk it messing up the engine. Sorry for any confusion it brought by saying it randomly

You could rule out exhaust if you just drop the downpipe and go for a short drive

I’ll give that a try when I get the car running and driving again.

How did you verify the wastegate actuator is fully closing the flapper?

took the actuator off and moved the flapper by hand to it’s open and closed position. And in its closed position the actuator bolts up no issues.

you pointed out using a 13g actuator on a 14b turbo in your original post. I’ve never had a 13g so I can’t speak to compatibility, but it is something to check considering different part numbers.

ill definitely keep that in mind and look further into it

 

[19Eclipse90]

I may be on an island with this, but I would suggest keeping the actuator bolted on and arm attached, remove the O2 housing to physically verify it is closed.

Fought a similar issue and couldn’t prove it until I did that. Changed the actuator and got boost back.

 

[import solutions]

pull o2 housing and be sure flapper is sitting