AlgaeHater

The boost pressure on the OBC display of my 1994 Turbo 3.6 is showing 0.0 bar in all driving conditions. The turbo itself is generating boost no problem and the car pulls hard when the boost builds. So far, I've swapped out the boost pressure sending unit along with the overboost sensor (both mounted to the intercooler). Any ideas what might be causing the OBC to show no boost? The OBC itself is working fine and other items (e.g. speed) seem to display just fine.

Metal Guru

Short of ringing out the wire from the sensor to the IP, take a pair of pliers and gently squeeze the female spade connector on the wire together. If they get removed a lot, they will open up and not make contact.
The connector on my overboost switch did this, resulting in a no-start after I reassembled my car after restoring the a/c system. After seeing that the fuel pumps weren't being enabled, I went back to the connector and squeezed it shut. Cured!

AlgaeHater

I took a look at the spade connector and it is clean and tight. Must be something else.

ianbsears

same thing happening to me and it was the sending unit on the intercooler. sorry couldn’t be more helpful.

doublecabmel

Mine has a delay in the reading, when going up or down in the boost. In addition, I'm only getting readings of .7 Bar and not .8

bweSteve

mine has always only ever read up to .7 (close to 2 decades now)

I thought .7 was the max

bweSteve

saw your new thread on this dblcabmel ... hope one of the top guys chime in

Metal Guru

The factory display will only read to .7 bar. I've ignored it for the entire course of my ownership.
There used to be a guy who modded the display to show all kinds of parameters, including actual boost, but he's been out of business for some time now. Cobalt has such a display;maybe he'll chime in.
I had to install a mechanical gauge to really know what boost I was running.
Last year I installed a Innovate PBR-1 gauge to take the place of the Innovate LM-1 handheld unit that rode shotgun in the passenger seat for 5 years. It displays afr and boost or peak boost (which is where I'm set now). I can plug a laptop into it and record afr, boost and rpm in graphic form.

bweSteve

that's cool

AlgaeHater

Update - turns out it was the turbo control module that died. My shop ordered a replacement unit from Germany.

fritz k.

I doubt that. the turbo schaltgerät (965.618.130.01, under the drivers seat) supplies voltage to the ignition unit, fuel pumps and lambda control module. if it had “died“ the engine simply would not run.

Actually there is no electrical connection between the boost pressure sensor and the turbo schaltgerät. See wiring diagram “instruments“.

Fritz

Metal Guru

The Turbo Control Module is actually mis-named. It's actually a safety relay; nothing more. If it gets a signal that the engine is turning over it enables the fuel pumps, Lambda module and the EZ 69 as Fritz states.
If replacing the boost sensor hasn't resolved the issue then the line has to be rung out.

heliolps2

There's also a blue relay behind the fuel gauge that controls the OBC. I might be wrong. but worth looking into.

Good luck bud

AlgaeHater

Replacing the "turbo control module" did indeed fix the zero boost reading. The service shop insisted that was the culprit and they were correct!

fritz k.

hi,
seems that your are willing to believe it, so thats o.k. for me.

Fritz