Boost stops at 1.4bar - N75?

[geneandbolly]

( i know...i don't have a bloomin' clue what they're on about either!!)

[UrS4boy]

Dave, he's seeing 1.8 bar on his dash and converting that to 0.8 bar of boost by subtracting the 1 Bar atmospheric pressure. We're talking about "Boost" not "Absolute Pressure".

That makes me crazy. Easier to just tell us what the digital gauge is reading.

[newsh]

Boost stops at 1.4bar - N75?

Sorry but you're still NOT getting the point.



If you only have the factory digital boost gauge which yields absolute pressures in BAR, even without an N75 connected, the waste gate spring should give you a boost under WOT of about about 1.42 Bar absolute (about 0.4 Bar (6 psig) relative boost). Any readout on your gauge less than 1.02 Bar is vacuum, no boost, just like a naturally aspirated vehicle.

Dave, he's seeing 1.8 bar on his dash and converting that to 0.8 bar of boost by subtracting the 1 Bar atmospheric pressure. We're talking about "Boost" not "Absolute Pressure".

[hunker7]

Sorry but you're still NOT getting the point.

If you only have the factory digital boost gauge which yields absolute pressures in BAR, even without an N75 connected, the waste gate spring should give you a boost under WOT of about about 1.42 Bar absolute (about 0.4 Bar (6 psig) relative boost). Any readout on your gauge less than 1.02 Bar is vacuum, no boost, just like a naturally aspirated vehicle.

With N75 disconnected, it shows 0.5 gauge pressure (1.5 absolute)

[hunker7]

After that it's back to leak tests I guess..

I hope that will be the problem. I found a nice silicone hose that fits on the turbo nicely, just need to make up a plug in coming days and off we go. *Fingers crossed*

[UrS4boy]

After adjusting the F96 I was getting 0.9 bar (1bar occasionally) , but I thought I am missing 0.1/0.2 due to timing, but now that that is sorted, it's still the same. I am now running on my dad's N75, so yeah, I will swap that over and see if that does the job.

Sorry but you're still NOT getting the point.

If you only have the factory digital boost gauge which yields absolute pressures in BAR, even without an N75 connected, the waste gate spring should give you a boost under WOT of about about 1.42 Bar absolute (about 0.4 Bar (6 psig) relative boost). Any readout on your gauge less than 1.02 Bar is vacuum, no boost, just like a naturally aspirated vehicle.

[newsh]

I keep going back to the fact that this all started happening after changing the fuel lines? It's weird..

[newsh]

After that it's back to leak tests I guess..

[hunker7]

After adjusting the F96 I was getting 0.9 bar (1bar occasionally) , but I thought I am missing 0.1/0.2 due to timing, but now that that is sorted, it's still the same.

I am now running on my dad's N75, so yeah, I will swap that over and see if that does the job.

[newsh]

@Dave. He's already subtracting the 1Bar atmospheric, we had all the confusion relating to this issue earlier in the thread. Ever since about page 3 he's been talking in terms of pressure of boost.

Anyway Janis, we now know for sure that the ECU is attempting to control boost, I'd be tempted to try the original WGFV again now just to see if you get the same numbers. In any case it seems the timing correction has had an effect, before I don't think you were seeing more than 0.8Bar (of boost) now we have 0.9 and even 1 Bar which is almost the mythical 1.1/1.2 (all be it at WOT in top gear).

One thing to bear in mind is that the factory URS boost gauge runs from the MAP sensor and a leak in the line to the ECU or even inside the ECU, will change the numbers quite a bit.

We've now fixed so many little problems and faults that we must be getting really close now..

[hunker7]

I am talking gauge not absolute pressure.

[hunker7]

I reckon it will be a boost leak, has to be. I am working next two days, but will get boost test done asap.

It goes to 0.9 then drops to 0.8 push it a bit more and goes back to 0.9.

[UrS4boy]

The factory fitted one.

0.9 bar with N75 connected, 0.5 bar with N75 disconnected. I did get it to tick over to 1 bar in 5th gear @WOT.

Makes no sense then. The factory digital boost gauge reads ABSOLUTE pressure, i.e. zero boost = about 1.01 BAR. So 0.9 and 0.5 Bar = vacuum, no boost at all. Max boost = 2.2 Bar (around 17 psig).

I'm off to London this evening for a holiday. Too bad I won't have the time to visit you and try to sort this in person. It's going to be something simple. What, I don't know.

[hunker7]

The factory fitted one.

[UrS4boy]

Fair enough, let's say I have a boost leak (making the test thing now), but how is it possible that nothing changes when moving timing by one tooth?

Because boost leak >>>>> one tooth correction.

What kind of boost gauge are you running again?