My 88 turbo is overboosting bad. The boost goes to about 15-16 before it stables out then falls to about 13. Nothing I do with the boost controller changes anything. I hooked the wastegate back up to the turbo outlet like stock to check and see if it was the controller and it still boosted the same. My suspect is the wastegate actuator. Is this a common problem? It's an S5 turbo. As far is buying a new actuator can, are the wastegate actuators the same for the S4 and S5? This is my first post, I'm new to the forum. thanks, stephen.

 

Did you recently make ANY changes to the car, such as adding an aftermarket exhaust or a new boost controller?

If you DID recently add a full (no cats) exhaust, that's the problem.

If you have not made any changes, I'd check to see if your wastegate hoses, lines, and actuator are working properly.

 

I just bought the car. It has the full RB exhaust with no cats and the Blitz SBCID boost controller. I checked and replaced all the lines to the boost controller and wastegate actuator with silicone ones and it made no difference. If no cats is a problem, how can i gain control of the boost? Can i upgrade the actuator? Or will I have to add a highflo cat to the system? thanks.

 

I am assuming if you are hitting that kind if psi then you must have an fcd of some sort... I would find out what else the guy did to the car before u bought it and that may help in deciding what could be wrong

 

The car runs great and does have a FCD. I'm pretty sure it's the wastegate actuator. Anyone know if the stock actuator/wastegate is capable of regulating boost properly with a catless exhaust system??? Might have to put a highflo cat in to tone it down. thanks for the help, stephen.

 

wow, I'm dissapointed with the NE section

the stock wastegate can't handle a strait through exhaust. you need to port your waste gate. and I would do it asap because you turbo will blow if it sees that kind of boost for too long (i know from experience )

it doesn't have anything to do with the actuator.

if you have any more questions feel free to pm me.

-Mike

 

Hey, I got it right!

 

thanks alot, wargasm and mike. You guys are on it. I'm porting this week. I'll post again once it's complete. Til then, i'll just be driving miss daisy.....stephen.

 

Remember that its cold to so that might have some affect on it to. During the summer time my boost would be a constant 10psi but during the winter it sometimes spikes to 12. This is with an S4 turbo that has the wastegate ported to 35mm and a new flappper welded in place.

 

Yeah, that too. Bought the car in south FL and it's done it from the very first time I got on it. So for this one, I'm sure the wastegate needs some attention. out.