94 850 Turbo Erratic Boost Problem

jdt1249 · Post by **jdt1249** » 26 Aug 2013, 09:54

Hello,
on my 94 turbo sedan I'm having an issue with boost. At times the car will boost fine, right up to about ten pounds while other times it only wants to hit around 5. From what I have read I am thinking either the tcv or the cbv. Stage 0 is up to date. The only thing that has varied is where I have gotten gas. Any help is greatly appreciated, thanks.

Post by **jblackburn** » 27 Aug 2013, 09:49

Sorry this topic has been overlooked.

I would think this is due to a weak spring in the CBV, but definitely check out the shape of all vacuum lines from the turbo to the TCV.

jdt1249 · Post by **jdt1249** » 27 Aug 2013, 13:34

okay, i might end up replacing the cbv. others have suggested that some of the piping is bad and to just get silicones, any thought on this? the lines on the tcv have been upgraded to silicone

Post by **matthew1** » 27 Aug 2013, 13:36

Does the boost vary during one single drive? Or is it a day-on-day-off thing?

Post by **jblackburn** » 27 Aug 2013, 13:36

If you're hitting the full 10 PSI at times, the pipes are fine, though it may be old.

Mine has blown through a couple of the original hoses, so the silicone ones wouldn't hurt, but I wouldn't expect it to fix erratic boost development - that's to do with the wastegate/bypass valve.

jdt1249 · Post by **jdt1249** » 27 Aug 2013, 19:29

thanks jblackburn
and matthew1, it is a day to day thing, not the same drive