Help with overboost

1986 Buick GX1

GX1 #001 [The One and Only]
Joined
Apr 24, 2015
I'm going to have to find something to use to pull the vacuum. Parts store had no idea what I was talking about. Go figure...how would I use regulated air to do it? Also, can I disconnect the hoses at the solenoid and pull through the Y effectively? I had a difficult time replacing those lines and they are zip tied. I'm thinking that a medium size syringe might work (but obviously no guage) Also Chuck, I removed the arm and the wastegate lever moves very easily. I went ahead and put penetrating oil on all the bolts. If necessary, can the wastegate portion of the turbo be separated and serviced without removing the rest of it? Thanks in advance!

Remove the hose from the wastegate actuator, connect an air compressor to the actuator. Start at zero and increase the air pressure to see when the wastegate starts to move.

The wastegate solenoid opens, bleeding air to atmosphere causing the wastegate to shut so the engine sees more boost.

It seems like you’ve checked everything except the actuator.

You could bypass the wastegate solenoid by running a manual boost controller. Any ball and spring type will work. Run one hose from the turbo compressor housing to the manual boost controller inlet and one hose from the manual boost controller outlet to the wastegate actuator.

Scoob mentioned connecting it tuner style which is connecting one hose from the compressor housing to the wastegate actuator. It seems a stock non-adjustable wastegate actuator starts to open at 8 psi or so, the ECM uses the wastegate solenoid to raise the boost from there.
 

Lockman

OH, OK .......Now I get it
Joined
Dec 6, 2018
Donations
$25.00
Sorry to butt in with my stupidity here , but if the waste gate actuator works on vacuum , how does it test with compressed air ?
 

1986 Buick GX1

GX1 #001 [The One and Only]
Joined
Apr 24, 2015
Sorry to butt in with my stupidity here , but if the waste gate actuator works on vacuum , how does it test with compressed air ?

That’s ok.
The wastegate actuator should really be referred to as a pressure diaphragm as it’s pushed open by boost pressure. Compressed air simulates the boost pressure from the turbo to open the wastegate.

The vacuum test is a quick check to see if the diaphragm leaks or not. If the diaphragm leaks, the wastegate will stay shut and you’ll have over boosting.

Even if the diaphragm does not leak, over boosting can occur due to the wastegate being stuck shut.

I hope I explained it better this time.
 

Lockman

OH, OK .......Now I get it
Joined
Dec 6, 2018
Donations
$25.00
Thanks, Man....you did. I don't want to steal any body's thread , but does this diagram look correct to you ?
WasteGate 'Y' Pic.jpg
 

SCOOBY DOO

I'M NOT A MONSTER, I'M JUST AHEAD OF THE CURVE!!!
Joined
Feb 18, 2007
I've HEARD if you mix up the tee you won't be able to go over 10 lbs of boost. As to the diagram, I don't know.
 

Kyleh24

86 GN , 87 White T
Joined
Jan 15, 2014
Thanks for all of your helpful comments and suggestions. Here is hopefully the final post (from me) on this issue. My OR wastegate actuator looked bad. The rubber that I could see was cracked. The rod moved under pressure, but I was unsure how much it should have moved. I had a used adjustable actuator. I matched the length to the OR non-adjustable actuator rod. I logged the next ride. Did I mention that I have a Powerlogger? I saw no change. Still around 30psi boost (with knock). I had a Map sensor in my parts box, that I didn't know if was good or not, so I plugged it in. The next recorded run showed boost topping out at 3psi. So I figure that I have possible 2 bad Map sensors? Did I mention that the Powerlogger gets its boost reading from the Map sensor? I had not removed the OR Map sensor, only plugged in the other one right beside it. So I changed it back to the OR map sensor. I had decided to order a replacement Map sensor and an adjustable wastegate actuator. I also decided to log one more short drive. The Powerlogger now showed normal (14psi boost) readings. See the attached picture. I still have the replacement Map and Actuator on order and will replace both. By the way, before someone comments, I know I still have the knock issue. It starts at 10 psi of (actual) boost. I will be addressing that issue next. Thanks, Kyle
 

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