22 replies to this topic

[The Stig]

Ok, serious topic this time.

I had my Defi BF's installed this week (Boost and EGT), and unfortunately the boost gauge is misbehaving.

The opening sequence for the gauges are normal (i.e. the lights go on and off and the needle goes all the way up and down, like the STi). However, when I start laying on the boost, the boost gauge slowly climbs up a few 1/10th of a Bar, quivers up and down for a bit once the boost hits full at around 0.4 Bar (my 850R should be hitting 10.9 PSI, probably around 0.7 Bar) and then spikes big time (up to ~ 0.8-0.9 Bar when the gears change. The thing is, the stock Volvo boost gauge is behaving normally all the time, and reacting properly (the boost goes all the way towards the end of the white strip).

I looked at where he installed the boost line for the gauge, and he sliced open the one orangey red-tagged one mid way and installed a T connected, and fed that to the defi boost sensor. I tried to make sure all the connections were tight, and they seemed to be.

Anybody know what's going on?

[turbor850]

I am thinking some sort of leak at the boost guage or around the hoses of the boost guage

[JHEIII874T5M]

the end of the volvo white gauge is 1 bar FYI.

[BlackT5]

Is there enough line to run it directly to the vacuum tree?

Maybe your gauge is fooked? needs to be calibrated?

[theunderlord]

Is there enough line to run it directly to the vacuum tree?

Maybe your gauge is fooked? needs to be calibrated?

ya, where'd you score this gauge in question? could be fubar = RED850R

[J0E]

Recheck the vacuum line going from the source to the sender. Make sure you are either tapping into the tree, manifold, or any real viable source for manifold pressure (don't have a pre-'99, so not familiar with it, but I get everything directly from the intake manifold). Also, check all the electrical connections and make sure everything has been done properly, even though the gauge itself will tell you if there is a problem somewhere.

I highly, highly doubt you have a faulty gauge. Most likely, you are running exactly the amount of boost shown on the gauge and there is an issue with the car itself. Search on the hundreds of threads where people are not running the boost they thought they were supposed to and troubleshoot from there.

BTW, stock boost gauges on any car are meaningless...

[The Stig]

Thanks for the help guys. I don't think the problem is with the gauge itself, or the wiring to the controller, as the start-up/shutdown sequence is normal. Where the problem lies is probably with the placement or leaks, or perhaps even the Defi sensor itself (although unlikely).

Ok, for those with 850s, I'll post a pic of what exactly the boost lines look like right now. Maybe that might give a better idea of what everything looks like.

[The Stig]

I'm not sure if he tapped into the stock boost gauge line, but I just took some pics of the install, and I'll post them once Will gets them on his site, so that you guys can have a look.

What I meant by the stock boost gauge was that it was behaving normally, and reacting much more quickly than the Defi one, and it was showing the normal amount of boost I'd expect (i.e. bout 7/8's of the way to the end of the white), so nothing's changed there.

[The Stig]

FWIW, the line that he cut seemed to travel into a metallic cylinder near the Turbo from which the wastegate comes out of. Does that help anyone?

[The Stig]

Ok, here are the pics of the install. Anything seem suspicious?

[lax01]

why do you have a t-fitting in the vacumn line that goes to the waste-gate? is your entire tree full?

[The Stig]

I assume it is, b/c that's how the mechanic installed it. Could that be the cause?

[TorqueSteer]

Wow those original vaccum lines look awful, i would suggest replacing them all. Just unhook that line and plug it into the vaccum tree, it couldnt possibly be full can it?

[The Stig]

Not sure, I'll have a look!

[styx0r]

Uhh, yeah, that's the line between the boost controller and the wastegate.

[JHEIII874T5M]

lol classic... ok... do this...

find your throttle body cover, take it off (held in by one screw) then you'll see



take one of the caps off and plug the line into there

[The Stig]

Thanks Joseph, I need a bit of hand holding when it comes to stuff like this. But manly hand holding, of course.

I'll go and buy some more vacuum hose tomorrow.

[theunderlord]

But manly hand holding, of course.

So much male bonding on volvospeed.