Was boosting 11-12psi / now only 8-9psi

[SuperFast3000GT]

I have a electronic boost controller and a actual boost gauge in the car. (Stock 9b's. Vac reduction/block off plates)

It's set to-

start boost 9psi (when wastegates are supposed to start opening)
Gain 38% (how fast the wastegates open)
Target boost set to 12 psi

Before I was holding in the 10-11psi range steady and spiking in the high 12's-low 13's.

I walked into a store last week and when I came back out and ever since I'm now only holding 7-9psi with the same settings and spiking no more than 10.5 and that 10.5 usually only happens on the first or second boost of my cruise. I made it boost a little higher by cranking up the boost setting to 13-13.5 but it backfired afterward. (running to rich?)

So, I just bought a 3sx pressure tester. When using a 12v tire pump I found a couple small leaks and fixed them (all i could find with such low pressure-biss screw/vaccum cap where the clutch booster was/BOV... and had already replaced my rear turbos intercooler pipe o-ring) but I'm still having the same issue. The tire compressor won't build any decent amount of pressure to do a real test so I need to get my hands on more air power, I know.

Until then, anyone have any ideas? Bad boost controller solenoid? Wastegates not sealing right? Or just a random boost leak that suddenly opened up?

I wouldn't think a turbo went bad. The car still doesn't smoke at all (rare for a 3/S) nor is there oil in my intercooler pipes. Also, the turbos sound fine...there's no whining sound or anything weird or different.

Someone, please tell me a boost leak could cause my car to still be able to hold a pressure that's steady because that's exactly what it does....it's just less now.

[VR-4 0wnz j00]

I would get a MBC and call it a day. A friend with a EBC had a similar problem. It wouldnt boost past 14.7lbs. He switched in a MBC and hasnt had a problem yet boost 18lbs. From what Ive been, EBCs are pretty unreliable.

[SuperFast3000GT]

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FYI- Before I went to into the store, everything was fine and the car was boosting fully according to my settings. I was probably indeed "raising some hell" though, just prior. (but no more than usual)

I usually sit and let my car idle and cool down before shutting it off but on this day, I was in a hurry. I was in the store for no more than 10-15 minutes. When I came back out, that's when the boost issue had started.

My electronic boost controller has a built in turbo timer but I haven't hooked it up yet due to being lazy and feeling like I don't need it. I just usually use good judgement and don't boost a lot when I know I am not far from my destination. If I do boost hard and come to a stop, I usually let the car continue to cool down a minute or two before shutting it off.

On this day I didn't, I just waited 20-30 seconds and went in the store. But, I did come back out and restart it not long afterward. (which is why I thought it would be ok)

Could that have caused this issue? Oil sludging in the turbo or whatever happens?


Something in the back of my mind said, "sit, and let this bitch cool before you go in" LOL but I didn't.... and now this. Just a coincidence?

[SuperFast3000GT]

I would get a MBC and call it a day. A friend with a EBC had a similar problem. It wouldnt boost past 14.7lbs. He switched in a MBC and hasnt had a problem yet boost 18lbs. From what Ive been, EBCs are pretty unreliable.

thanks for the reply! Did he change the settings any? I can raise the actual boost I'm getting up by raising the boost setting or increasing the gain on the controller... but under the normal settings that I have been using for a while... it's not the same anymore.

[O_ROD]

Sounds like a boost leak to me. Find someone with a compressor and pressure test up to around 15psi. Make sure to disconnect and block your PVC return line when doing so.

After you get that out of the way, if the problem still persists, we can look at other things.

[CoreyB]

A leak in the exhaust could do it. Like the rear manifold warped, as they all do eventually.

Steve

Or a cracked front manifold which is super common as well.