1994 850 T5 - Boost gauge goes left

Rainer · Post by **Rainer** » 02 Oct 2022, 04:32

The board was out for changing the lights. Being in again, I see the boost gauge going to the left, as I start the engine and back, as soon the engine stops. It shows normal function, but twistet to the left.

Post by **Clemens** » 03 Oct 2022, 23:00

That is really far to the left. Check the vacum hose at the back of the cluster. My guess though is that the boost gauge assembly is not seated properly. It looks like it is mounted a few degrees to the left

Post by **scot850** » 04 Oct 2022, 18:55

I have no idea how the boost gauge works. It sounds like it has a vacuum port that moves the needle. Did you remove the pipe? Is there 2 ports by any chance and you have connected it to the wrong one?

Neil.

Post by **Sveedy** » 04 Oct 2022, 21:00

Single vacuum port, and if it's disconnected, the needle sits at 12:00. Normally.

Post by **Clemens** » 05 Oct 2022, 00:05

there must be a spring that works in both directions. if the car idles (and has vacum because the pcv is clean), the needle moves to the left. under boost, it moves to the right. The gauge is fed with vacum through a long hose running off the tree at the intake manifold. If that hose breaks, the gauge stops working.

This is a weird symptom, I can only explain that it is seated in a weird angle..Maybe he twisted the hose while disconnecting it.
Btw., on my 94 T5M the gauge has been a little to the left as well since I removed the gauge cluster a year ago, but just a few degrees, not as much as in this case.

Rainer · Post by **Rainer** » 03 Feb 2023, 02:49

Many thanks for your replies. I was not able to read them up to now. So sorry for being late.
Up to the „repair“ it always showed „0“ and only went to the right while running.
Now it jumps to the left, as soon I start the engine, but works correct from the new „0“. As I understand: Going left - turbo sucks??? Going right- turbo blows. Perhaps the AGR Valve?

Post by **Clemens** » 03 Feb 2023, 14:51

The Turbo can only boost, from very little to quite some. It can't suck.
Simply put: the neutral center is where the needle should be with the ignition off. If the engine idles or you cruise with really little gas (and the PCV system is clean) you should see the needle go to the left, but not as far as in your pic. If you give it more gas, it will move towards the center, and - as you implied correctly - full boost will make the needle move to the right.

I can only imagine that either the gauge broke (maybe the spring that should hold it centered if not running) or that the gauge moved by a few degrees while working on the gauge cluster.

My feeling is that you need to get in there and twist it back to where it should be.