Boost control system

[kjhansen]

Having nothing better to do during this rainy weather, I was closely inspecting the boost control system on my TR. 

First: the wastegate control valve/solenoid was not attached to anything except its wires. 
Well, it is NOT the stock turbo, it's a Precision Turbo PTE 5858 and there is a tube running from it down under it towards the wastegate controller. So, obviously the stock wastegate valve thing is out of the loop now. However...

Second:  The tube running from the compressor side of the turbo and just long enough to reach around it and hook to the wastegate controller wasn't connected to anything either. I assume it was supposed to be attached to the wastegate controller?

Third:  I checked the adjustable rod from the wastegate controller to the wastegate.  There didn't seem to be any more threads left to tighten it up.  But I popped the clip off at the swivel and removed the rod from the pin to check it out.  It seems to be almost all the way back--maybe one or two threads showing.  Oh well.  But after I took it off, I tried to move the wastegate swivel and it would not move either direction.  Now, I admit it's been 12 years since I fooled with my first Turbo Regal, but I seem to remember that you could swivel that swivel.  I mean, it's the wastegate.  How does it open if it won't move? This is obviously not the stock system, and I don't know how it works, although it seems to work.  I understand how the stock system works, but this appears to be different.  I called Precision Turbo, but just got voice mail.  If anybody could explain I'd appreciate it.

Keith

[Steve Wood]

Factory set up used a "Y" style hose that connected the compressor and the actuator to the wastegate solenoid.

If the end of the hose that went to the solenoid was plugged, the wastegate would open and limit the boost to about 12 psi.  that with the wastegate rod adjusted to about 1/8" of tension on the waste gate actuator.  If one was to shorten the wastegate actuator rod so that it put more pressure on the wastegate flapper in the exhaust housing, one might get as much as 18-20 psi out of the turbo.

If the hose was removed from the solenoid and left unplugged, the boost would go higher and probably cause a blown head gasket.  It was popular in the early days to disconnect the solenoid and put an aquarium valve in the end and adjust how much boost was leaked out the valve.  The more, the higher the boost would go before the gate opened.

Now, as I mentioned, the boost would normally go under control to 18-20 psi.  When one wanted more, he went to a heavy duty actuator that had a stronger spring in it.  This would allow one a minimum boost of about 18 psi but might go as high as say 28 psi before the wastegate would open dependent short the actuator rod was shortened.

Next came "tuner style" boost control.  We eliminated the solenoid completely and did not use an aquarium valve.  The hose went straight from the compressor housing to the actuator.  This allowed boost to be controlled solely by the actuator rod length.  The down side often was that the boost spooled up slower as the actuator started creeping earlier and allowed boost to leak off prematurely.

Then we started using manual boost controllers.  They usually use a spring and checkball inside an adjustable valve that is adjusted by length.  These keep the boost off the wastegate in the exhaust housing until a desired boost level is achieved and that creates a faster spool up.  I suspect these are the most popular today as opposed to electrical controllers that control leakage thru a pulse width...they cost a bunch more.

It's a wonder that you have not blown it up if there was no hose connected between the compressor housing and the actuator.  It may be that the turbo has a larger hole in the exhaust housing that allows the gate to be blown open earlier, or maybe the hole in the housing as been opened up to a lot larger to handle the flow of a bigger turbo and it is not being sealed off so pressure is escaping much earlier than it should.

[kjhansen]

It's a wonder I didn't blow it up.  When I found out the tube was disconnected (today) I connected it and did a WOT run, but just in 2nd gear.  Even with the tube connected the gauge showed 29psi (!!!!) before I backed off.  No audible knock (!!), but Scanmaster replay showed it had a high of 4 degrees of retard during that run.  I've been driving it around this way for months!  Fortunately, not doing many WOT blasts. At first I was so focused on controlling the car during the WOT blasts that I did do that I had no time to watch the boost gauge, which is on the a-pillar.  I mean, the thing went so hard it was startling and would go sideways if you weren't careful.  Not surprising at probably 30+psi.   I'm still not a member of the DOTC Club though. 
Gotta tell ya, that much power is addicting.  I hate to but I have to give it up, I know, but it was fun while it lasted, and engine is still together!

However, I'm not sure I can adjust the boost down.  The wastegate doesn't seem to want to move at all (see point 3 in original message) with the wastegate rod disconnected.  I guess I need to take the turbo off, which I don't like to do.  It's when I replaced the turbo on my other car that I started having problems.  Couldn't get the exhaust-to-turbo gasket to seal properly after that.  Probably the cheap aftermarket gaskets I bought.
 
And I used to be one of those guys with an aquarium valve...  looked tacky but sorta worked.

Keith

[Steve Wood]

First thing to do is to lengthen the rod as much as possible until there is only about 1/10-1/8th inch of pull on it to connect to the wastegate arm (when it is closed).
If you have source to air, you can try blowing into the hose going to the actuator and the rod should move out of the actuator toward the wastegate arm.  If you try sucking on the hose, you should get a vacuum against your tongue.  If you can suck air thru it, then the diaphragm in the actuator has gone bad.

[kjhansen]

I'll give it a try.
Keith

[kjhansen]

So I disconnected the tube from the turbo to the wastegate controller and blew in it and sucked on it.  I couldn't blow hard enough to move the arm.  I connected a 12v tire pump to it and it moved the arm easily.  Sucking on it didn't show any leak.  However, when I hooked it all back up and attached the arm back on the wastegate lever and applied pressure from the 12v tire pump, the arm wouldn't move at all.  The wastegate is locked up.  I'm going to have to remove the downpipe and see what's going on.
Or live with 30psi boost.  Hey, I've been doing it for 8 months now.
Keith

[Steve Wood]

Lol! Frozen arm might give you some boost. Better pull the dp and unstick it

[Tim Hensley]

if it a TA down pipe they have a repair puck and arm to fix a small engineering mistake
you have to call and talk to Tim not one of those thangs he has in his catalog. It a easy repair, WD40 might free it up, but it was worth the effort, it hs never stuck again
 

[1 RARE T]

Likely just carbon is sticking the puck.

[kjhansen]

Not a TA downpipe unfortunately.  It was bought 10 years ago from Kirban, and they don't even remember who their source was back then.  Anyway, got it loose, sort of.  It will move but has to be forced both ways with a pair of vice-grips. Looks like the shaft is coming apart in the hole.  Time for a new downpipe.

[Tim Hensley]

This is a picture of a RJC biggie puck repear kit weld on arm , the TA kit bolts it’s not that hard to fix and the RJC would work on the TA. I think there all the same.

[kjhansen]

Thanks.

[kjhansen]

I know it's been a long time, but here's an update.  I sent my downpipe to RJC and they fixed it.  The wastegate swivels freely when not attached to the boost control rod.  I also ordered the boost controller from RJC.  We'll see how that works when it gets here.
Keith

[Steve Wood]

better late than never!  Glad you "gotter dun"

[Tim Hensley]

We are lucky to have people helping and supporting such a small community of people
Just look around how many turbo Buick did you see this week besides the one you walked by in your garage