Problem controlling Boost

[T-Type Mike]

I started to encounter boost issues late last season, Now that the car is almost ready to be driven again it's time for it to be addressed. I have a stock adjustable wastegate that does not seem to seal the puck at all. I adjust it longer to keep boost down, but the bloody puck just rattles away... Would you guys agree that it sounds like its the actuall actuator thats shot??? Any input appreciated, Thanks Mike

 

[blackbuick87]

I think you have the problem backwards. If you cannot keep the boost down the puck is sealing just fine. The problem may be the wastegate hole is too small and cannot bleed boost off fast enough.

 

[blackbuick87]

What kind of downpipe? Stock elbow? Is it ported?

I would port the elbow and you should see a mark on the turbo where the puck sits. If it is over to one side you may be able to open the hole some to that direction.

 

[BEATAV8]

Sounds like you may have a bad actuator. A hole or rip in the diaphragm would render it useless (i.e. it would not move) and the car would overboost.

OR... if you have an ATR 3" pipe with an integral wastegate, you may have a sticking issue. There was a known material issue with their early integral WG pipes. If you suspect this is the case, call ATR. They will take care of you.

 

[OKTurbo]

The WG actuator on a stock setup is fairly easy to check with a MityVac tool. (have to use the MityVac that can swith to pressure)

Hook it up to the diaphragm on the actuator and pump away.....you should see it start to move at around 10-12 psi....and it should hold the pressure. If you mityvac gauge starts dropping then you have a leak in the WG actuator diaphragm.

I've seen a lot of boost control problems be traced down to the 'Y' fitting orifice. There was a bad batch of these that got loose....genuine GM part, but the orifice measures at .026"....the proper size is .050".

If you've put a new one on recently, take the Y fitting off and check the size of the orifice with different sized wire....I used music wire....guitar strings also work....just need to know the size of wire.

Also...check your "base" boost setting by pulling the line off the WG solenoid and jamming a golf tee in there. Go for a drive....the boost should go up and stay steady at around 10-12 psi. This helps to diagnose a bad WG solenoid. If the boost is still crazy with the golf tee in start looking for a leak in the boost control lines.

Good Luck,
John

 

[Joel_E]

Since you said it was rattling away... I would agree with MJRWOOD that it may be your puck sticking. I had a problem with inconsistent boost then came a rattle. Traced the rattle to the puck sticking just off its seat. Sent the downpipe back to ATR and the replaced the puck assembly. If its rattling try using a wrench to close the puck even more, if its stops its stuck.

 

[T-Type Mike]

Thanks guys for your input. The Downpipe is a Kirban 3" with ported stock elbow. The wastegate hole is opened up to .900 on my TA-49. I do suspect the wastegate is bad, very hard to move, but will also check the "Y" aswell, I will let you guys know how I make out, Thanks again, Mike