boost problem

[gndeligirl]

Help, I cant seem to get the right amount of boost. My boost is to high. 93 chip my boost runs away at full throttle 25psi. lots of pinging of course. New boost solenoid, solenoid disconnected its 10psi. The knock sensor does not seem to work scanmaster reads 820 o2 but no knock retard is this related. Adjusting the waste gate actuator lower for less boost looses power. Whats a good starting point for adjusting the wastegate. Thanks

 

[UNGN]

You may need to check the orifice size on the wastegate Y fitting. Has this been changed in the last year? Some wastegate orifi were made with a .030" restriction instead of a .050", causing the boost to be too high.

Has the wastegate actuator been changed to a high boost actuator or HD actuator? This is a No-no for a street car, unless you have a monster sized puck on your down pipe or elbow and have ported the wastegate hole to the max. Otherwise, the force it exerts on the wastegate will be so great that only boost greater than 18+ psi will allow it to open, even at the maximum rod length setting.

If the wastegate actuator is not a highboost model, set the wastegate rod length to somewhere between 5.25 and 4.90 inchs from the center of the hole to the face of the actuator (with the rod disconnected from the flapper arm of course) The longer the rod the lower the boost will be. The above dimensions should get you back close to stock boost levels (if your orifice is .050")

 

[Turbosix6]

My best advice would be to replace the vacum lines leading to the turbo from the solenoid and install a new Y splitter - but, at the end of the day, if your still running the stock wastegate you will never have steady boost numbers anyway.

This usually takes care of any boost control issues:

Terry Houston DP
New Wastegate actuator
Replace all vacum lines, BC solenoid and Y splitter
Remove or replace Cat
Good exhaust system

 

[JToups386]

Yep,,, first check for cracke/split lines that affect this part of the system. If you are using the wastegate solenoid to control boost, make sure you're not running a chip that was designed to max out the boost. I realize you said it's a 93, so I'm assuming it's not one designed to run higher boost levels for alcohol setups or low timing? Never hurts to ask...
Is this car new to you? Do you know about all the components on it? Check the things mentioned in these last few posts, and get back to us with further info, if you don't solve your problem thereof.