I have had very erratic boost pressure readings for quite a while in my 87 TII. The only mod's are a K and N filter and a open exhaust system.

Sometimes the turbo works fine - spools up at a very low RPM (probably due to the low restriction in the exhaust system) and the boost goes right up to maximum (around +35 on the gauge). The next day I can hear the turbo spooling up a little but I'm lucky if I can even get a positive pressure reading. Sometimes it won't even come up to zero on the gauge.

I put a separate pressure gauge in the system to see if was just my factory gauge and the readings are almost exactly the same.

I have also checked and lubricated the linkages on the turbo (wastegate, etc.) and it didn't look like anything was wrong.

Has anyone ever had this problem and what should I do to fix it? I thought that maybe my wastegate was sticking open, but I don't know how to check it.

Any useful information would be greatly appreciated. Thanks.

 

Try wiring the twin scroll open for a few days and see if it goes away. Its been known to seize closed but that should restrict boost to like 4psi, not 0.

 

I will try it. What do I do, disconnect the linkage and then tie it opened with a wire? Thanks

 

I thought the twin scroll was only on s5's?

Anyways sounds to me that you have a problem with your wastegate actuator sticking open, or your boost duty control solenoid sticking open.

Do you have an MBC you can install?

 

Twin scroll was only used in the S4 ('86-'88).

Don't lubricate the wastegate parts. They were designed to run dry. I would imagine that the wastegate actuator and/or arm is sticking.

 

Chances are the wastegate is sticking. However my turbo was doing some funky things like that before it craped out. You may want to check the turbo itself.

 

I know this is an old on, but how do you "unstick" a wastegate?

 

Buy a real boost gauge. When my gauge started doing that, I started flipping out. Don't trust that thing, it's for decoration only IMO...

 

My turbo has been doing sort of the same thing...the other day i was poking my finger around down there where the waste gate actuator is but i didnt touch it, atleast i dont think i did. So now my turbo will spool up very early, especially in 5th gear. When im in 5th if i barely accelerate at all my turbo starts to kick in. Also now the whistle seems to be much louder, and prominent over all the other sounds. The whistle is much more high pitch. Do you experience that in your car jeffpulano?

BTW i can still get a good bit of boost out of my car. I never floor it but if i put it half way to the floor it gets up to about halfway on the gauge, so i figure i could get it maube 3/4ths up the guage.

 

Yeah, mine has been doing pretty much the exact same thing. Is the wastegate causing it?

 

i think either the wastegate is stuck open or there is a nice crack in the turbo manifold. I'm leaning more towards wastegate because i cannot get my boost more than 1/2 on the gauge no matter how hard i punch it.