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[Kenny Rogers]

If that's the case you might see a little improvement.  As the saying goes, your exhaust is only as big as your bottleneck.  If that 2" section is on there it still might choke.  Meh, give it a try.

[glustic]

Damn I forgot about your cherry bombs... Unhook that shit where they begin and see how it goes.

Question:

How long have you had the cherry bombs + 2" of pipe and stock muffler on for? Have you ever been that hard on your car after you installed the restrictive shit?

[patsmx5]

Damn I forgot about your cherry bombs... Unhook that shit where they begin and see how it goes.

Question:

How long have you had the cherry bombs + 2" of pipe and stock muffler on for? Have you ever been that hard on your car after you installed the restrictive shit?

The cherry bombs are wide open 3", so they don't cause much backpressure. The 2" pipe and stock muffler went on in Late July, and I haven't driven it hard since then till just a few days ago when I got my ignition to stop cutting out after 4500.

[glustic]

Damn I forgot about your cherry bombs... Unhook that shit where they begin and see how it goes.

Question:

How long have you had the cherry bombs + 2" of pipe and stock muffler on for? Have you ever been that hard on your car after you installed the restrictive shit?

The cherry bombs are wide open 3", so they don't cause much backpressure. The 2" pipe and stock muffler went on in Late July, and I haven't driven it hard since then till just a few days ago when I got my ignition to stop cutting out after 4500.

Thats probably your problem then man...

[bigdaddyvtec]

If you have a flex pipe in the setup... make sure that the insides of it havent collapsed in on itself... Seen it more than once....

[patsmx5]

No flex pipe on here. Never would have though of one collapsing though. Hell something in the stock muffler could have collapsed for all I know.

[HiProfile]

If the diaphragm in the WG has a hole in it, it will leak boost from there. It won't open the valve, but you also won't make boost. This will overspin the turbo, pushing it into an inefficient portion of the flow map. Check those lines on most maps, 150k on most turbos is 60% or less...

The other thing is the seal around the WG's valve, specifically the 'valve guide' seperating the upper bulb from the exhaust gasses. If manifold pressure leaks in there, you get that pushing the valve open, and boost crashes.

Lastly, and most likely, your stock 2" muffler is holding it back a lot. With the EBC at a fixed duty cycle, I get 10psi with my e-cutout closed and >18psi (most I've tried) with it open. Same stock-muffler deal as you.


One thing you might try is to pressure leak the ENTIRE system, exhaust and all. Get a plumbing test plug for your exhaust, and replace the filter with a pvc cap w/valve stem. You'll get some leakage through the rings and head, some though the CHRA since it's not oil-pressurized, but you'll be able to find some other large leaks. Just don't go crazy with pressure if your PCV setup sucks, you'll blow out an oil pan or VC gasket.

[skaterdudz02]

I have the same issue and it's a little tricky. Having a pcv setup with catch can could do it along with no check valve on the booster.

[patsmx5]

I suppose if exhaust was leaking in through the valve guide then it could push the diaphram open. That's the only scenario where I could see getting less than wastegate pressure. But I doubt that's the case as it didn't do this before, and I had the WG off a couple months ago and the valve guide was tight like new.

The exhaust system doesn't leak, none. Last time I had it off, I found two tiny tiny pinhole leaks. I welded them up, ground them down, and they were fixed. I ground all the flanges flat before reinstalling and have inpsected them with a mirror and light; they do not leak.

[bigdaddyvtec]

If the diaphragm in the WG has a hole in it, it will leak boost from there. It won't open the valve, but you also won't make boost. This will overspin the turbo, pushing it into an inefficient portion of the flow map. Check those lines on most maps, 150k on most turbos is 60% or less...

The other thing is the seal around the WG's valve, specifically the 'valve guide' seperating the upper bulb from the exhaust gasses. If manifold pressure leaks in there, you get that pushing the valve open, and boost crashes.

Lastly, and most likely, your stock 2" muffler is holding it back a lot. With the EBC at a fixed duty cycle, I get 10psi with my e-cutout closed and >18psi (most I've tried) with it open. Same stock-muffler deal as you.


One thing you might try is to pressure leak the ENTIRE system, exhaust and all. Get a plumbing test plug for your exhaust, and replace the filter with a pvc cap w/valve stem. You'll get some leakage through the rings and head, some though the CHRA since it's not oil-pressurized, but you'll be able to find some other large leaks. Just don't go crazy with pressure if your PCV setup sucks, you'll blow out an oil pan or VC gasket.

I have had a diaphram fuck up, and the fucker will creeep NOT drop boost.  BUT also had a issue with Joe from speed factories car and Dropouts with the flex pipe issue... SAME fucking symptoms

[HiProfile]

I have had a diaphram fuck up, and the fucker will creeep NOT drop boost.  BUT also had a issue with Joe from speed factories car and Dropouts with the flex pipe issue... SAME fucking symptoms

It probably is mostly exhaust, but on smaller motor/turbo cars, a torn diaphragm + mbc/ebc will allow boost to drop from the weak spring still opening as air leaks out. I've had that issue on a setup more similar to his, 50trim T3 and 1.6L motor, and mine barely boosted at all.