Boost control issue.

[shadows672]

So I've had my R33 for a few months now and I've recently been having boost control issues. I have Greddy profec B Spec II and its acting very strangely. It drives fine and holds boost until it hits peak boost (14psi) then it will no longer make any boost. The display says it's making around 1psi. But then after leaving it for a while it will work fine again, rinse and repeat. Is it the solenoid sticking open? Any help would be great. 

Cheers 

[vetter2769]

does the car feel like it drops 14psi?

you'd certainly feel the cut or decrease in power,

if not its probably a setting within the boost controller,

look into how to set it up correctly.

 

[shadows672]

Yeah it definitely boosts to 14psi, change gear and then no boost. I've set it up properly and had a look at the settings, everything seems in order. 

[shadows672]

when I say everything is in order, I mean the settings look right but the problem is still there. 

[admS15]

Possibly wastegate is getting stuck open. That makes sense from what your describing. Disconnect the wastegate arm, operate the flapper by hand and check that it opens and closes freely. Is the dump pipe stock or aftermarket?

[shadows672]

I'll give it a go but I'm not sure that's it's the wastegate because when I take out the power from the Greddy unit it makes boost. It's an aftermarket split dump. 

[admS15]

Well if it works fine with the boost controller unpowered then the issue definitely lies there. The thing is, if it's switched off, the lowest the boost can go is wastegate spring pressure and i would expect that to be between 5-7 psi. You said when it plays up your only getting 1 psi. Since you have an aftermarket split dump, i would definitely check the flapper opens and closes smoothly and doesn't get caught open. Some of the split dumps have a reputation for causing this. Wont take long to check and rule it out as a possibility if it's all good. Cheers.

[shadows672]

So I had a look today and it does like the waste gate is getting stuck open, any ideas for a fix? Looking to get a tune soon so need to get this sorted. 

[admS15]

You're going to have to determine why it's sticky. Most probably it is fouling the inside edge of the dump pipe. You will have to take the dump off to take a look and either dremel it for clearance or replace it with a bell mouth dump. The other possibility is the flapper mechanism itself is faulty and sliding in and out. Pull the dump, diagnose and then take action. Cheers.

[shadows672]

Alright mate, thanks very much for your help

[admS15]

No probs. You could also try spraying some wd40 or similar on the shaft of the flapper and open and close it quite a few times and see if that frees it up before you go pulling shit off. I use to have a turbo on an old car of mine that had a sticky gate and doing that would remedy it for a few months. Give it a shot, can't hurt. Good luck