Boost control issue help

I’ve got a 2000 mr2 spyder with a 1zzfed and an internally wastegated Garrett turbo. Suddenly the previously well controlled hallman boost control is all over the place, when its cold it way overboosts and when its hot, it takes forever to build boost then overboosts. I run 8psi and it’s spiking to 15(!). I took off the wastegate actuator and manually moved the wastegate and it felt kinda crunchy, so I sprayed some lubricant in there and it freed up but did not resolve the issue. It’s my daily and taking the downpipe off to inspect is going to really suck. I think I’m going to take out the hallman and see if it does this on straight wastegate, ana swap out the spare diaphragm that I have.  Anything else I should check? I have a spare car with a similar(ish, 2zz swap) setup to swap parts for diag.  

If you have some sort of electronic boost control, make it go away.  Either the controller or the bleed solenoid is pooched.  

Its got a hallman manual boost controller. 

I'd wonder if that wastegate arm is still moving well when the housing is hot.

Could be lots of things.  In no particular order, exhaust leak, intake boost leak, wastegate signal line leaks, wastegate flapper not moving smoothly and sticking open, or MBC ball valve sticking.

I'd start by reverting to a mechanical wastegate setup and carefully inspecting all of the intercooler/intake lines and couplers for leaks.

I smoke tested the intake and exhaust, both pass. Has anyone encountered a wastegate that seizes when hot? It’s tough to test cause, well, it’s hot when it’s hot. 

If you have a Mityvac style hand pump you can pressurize the wastegate cold and check it again when everything is hot.

Manual boost controllers can get sticky as well.

Carbon said:

Its got a hallman manual boost controller. 

I bet it leaks 

Knurled. said:

If you have a Mityvac style hand pump you can pressurize the wastegate cold and check it again when everything is hot.

 

Manual boost controllers can get sticky as well.

Good call, I have one of those. I was dreading trying to manually actuate the wastegate hot, this is a better simulation of real world operation anyway and I won’t burn the berkley out of my hands doing it! Well done! 

So i deleted the boost controller, no change at all running boost pressure straight to the wastegate actuator. Tomorrow I’ll use the mightyvac on it but it’s looking like a turbo or actuator problem.

Thrilled. 

If you're lucky it's a actuator problem, if you're not so lucky it's the wastegate coked up. You could try some marvel mystery oil and lots of moving back and forth or take it apart and oven cleaner. 

"it takes forever to build boost then overboosts. "  Like the waste gate is stuck partially open.

In reply to Dr. Hess :

It does doesn’t it. :-/ 

Thats where this whole thing has been leading me. Got an aching feeling this things gonna need a turbo. Well, opportunity for upgrade I guess. I think if that’s what it ends up being, I’m gonna do a rally potato on the 2zz car and steal that cars gt28 for the 1zz car. 

Edit! Woah those are expensive! Nevermind!

Er?

I thought the GT28 WAS the "rally potato".

G Pop Shop is a nationally known turbo rebuild house the tooner kids use and is located about 30 minutes from me.  I had them do the turbo in the 4th gen 3SGTE I put in the RAV. The first one was grenaded and not rebuildable, which was a bit of a problem with a turbo built specifically for one application, JDM only.  So I bought a whole other motor just to get a rebuildable turbo core.  The turbo on it was OK (I made sure on the phone talking to the guy in the warehouse,) and G Pop Shop said it was runable as it was, but I had them rebuild it anyway just because it's made from unobtainium.  Anyway, I recommend them for rebuilds.

So the wastegate was seized, i hit it with copious amounts of penetrating lubricant and worked it while flushing with penetrant, seems free now. Time will tell, but it seems good for now. Thanks for the insight.