2G Won't hold target boost, drops off

[Benjamin1997GSX]

As the title says I've got a 2g gsx that's tuned to make 17psi on a B16G. The target boost is 17psi or roughly 1.2 KgCm2. It will hit 17psi but it won't hold it for long before dropping off to around 14psi. The car hasn't had any major changes recently and has consistently held 17psi. My first thought is boost leak. I've looked and haven't found any obvious leaks but it's possible it's something smaller I'm missing since it's still holding 14psi. My botched homemade boost leak tester also probably isn't ideal. I have no reason to think its a Wastegate or boost controller issue since neither has been messed with recently. Any ideas?
Any help provided is appreciated. Thanks

 

[chrysler kid]

Does your exhaust manifold have any cracks in it? Is it original or aftermarket?

 

[Benjamin1997GSX]

Does your exhaust manifold have any cracks in it? Is it original or aftermarket?

It's a relatively new FP manifold. The last one had been on the car for a long time and eventually did crack.

 

[chrysler kid]

Then besides checking the obvious, like loose hoses or loose bolts on the exhaust manifold to the head, you will need to do a boost leak test.

If thats something you cant tackle at the moment, you can try removing and cleaning the pcv valve.

Are you running the stock blow off valve or an aftermarket one?

 

[Benjamin1997GSX]

Then besides checking the obvious, like loose hoses or loose bolts on the exhaust manifold to the head, you will need to do a boost leak test.

If thats something you cant tackle at the moment, you can try removing and cleaning the pcv valve.

Are you running the stock blow off valve or an aftermarket one?

It's a Greddy Type S, and I need to order a boost leak tester. With the amount of boosted cars I have, I should have one by now. I'll try the PCV valve but I don't know why it would cause these symptoms.

 

[slugsgomoo]

you can make yourself a boost leak tester with a couple dollars worth of parts at home depot- here's a handy how-to on vfaq.com - boost leak tester

 

[curt-s]

You can also create your own tester with ABS elbow, cap, a couple of rubber couplers and clamps, an air valve, and a threaded fitting. The couplers get dicey after 20psi or so, as they'll tend to slip but this can also be solved by making the surfaces of the ABS pipe grippy (rough, stepped, or threaded)

..
now that I've said all that, it's so much easier to just buy one.

 

[DSMPT]

What wastegate spring pressure and boost controller do you have?

 

[Benjamin1997GSX]

What wastegate spring pressure and boost controller do you have?

I'm not sure what spring pressure is. The boost controller is an old school HKS EVC3

 

[DSMPT]

I'm not sure what spring pressure is. The boost controller is an old school HKS EVC3

What boost pressure do you have when the boost controller is off? and how do you read the boost pressure? Log or gauge or boost controller display?

 

[Benjamin1997GSX]

What boost pressure do you have when the boost controller is off? and how do you read the boost pressure? Log or gauge or boost controller display?

I've never had it off but it's possible that one of the lines from the controller to the wastegate is leaking and that's causing it to drop to spring pressure. I assume that's what you're thinking? I read it from a GReddy analog gauge that's measured in KG/CM2.

 

[DSMPT]

I've never had it off but it's possible that one of the lines from the controller to the wastegate is leaking and that's causing it to drop to spring pressure. I assume that's what you're thinking? I read it from a GReddy analog gauge that's measured in KG/CM2.

I am thinking this may be just overshooting (spiking) by the boost controller's improper setting or installation. Did you set the EVC3 properly? I remember that the EVC3 was a bit complicated to set at the initial setup.

 

[Benjamin1997GSX]

I am thinking this may be just overshooting (spiking) by the boost controller's improper setting or installation. Did you set the EVC3 properly? I remember that the EVC3 was a bit complicated to set at the initial setup.

The boost controller has been on it long before my ownership. I think the records show it was installed around 2003. I haven't messed with any of the settings and it's consistently made 1.2kg/cm2.

 

[DSMPT]

The boost controller has been on it long before my ownership. I think the records show it was installed around 2003. I haven't messed with any of the settings and it's consistently made 1.2kg/cm2.

As much as I remember, the EVC3 unit needs to learn the stock boost pressure before start using and it will control the boost pressure based on that stock pressure. So, for some reason if the base stock pressure in the unit memory is gone, it needs to learn it again, otherwise it would act unstably until it learns the stock pressure again. This may not be the cause but just came to mind.
Also, I would check tiny air filters for valve unit if still has, since it's installed long time ago maybe clogged or cracked.