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View Full Version : Does Adjusting the wastegate actuator make the car run a higher boost?



Tallpointy
Friday 11th March 2005, 14:52
It's a numpty question, but it's where my level of knowledge is at the moment!

Also,
what is the standard boost for an 850 T5 in PSI?
The reason I ask is because I want to fit a BOV, but many spec. that the boost must be greater than 10PSI.

Thanks

Pedro Fandango
Friday 11th March 2005, 14:59
personally i would buy a MBC instead of play with the wastegate to raise the boost

Wobbly Dave
Friday 11th March 2005, 15:05
At full chat you should be able to produce 0.7 - 0.8 bar

0.7 bar = 10.1526416 pounds per square inch. Best buy and fit (if only temporarily) a calibrated boost gauge.

You will need to blank off the recirc valve if you wish to fit a dump valve. I believe there is a how to in the knowledge base.

volvotuning
Friday 11th March 2005, 16:41
bit less than that, more like 0.6-0.7 bar.

Adam.

Wobbly Dave
Friday 11th March 2005, 16:45
I was nearly right :hidesbehi

Giles
Friday 11th March 2005, 16:46
At full chat you should be able to produce 0.7 - 0.8 bar

0.7 bar = 10.1526416 pounds per square inch. Best buy and fit (if only temporarily) a calibrated boost gauge.

You will need to blank off the recirc valve if you wish to fit a dump valve. I believe there is a how to in the knowledge base.

just tried to do mine. No guage so was careful as to the turns (3 full turns) and seemed great at low rev's, but seemed to drag/dawdle at about 4,000 onwards - have reset back to normal. Any ideas as to why there was a sort of spluttering from 4,000?

volvotuning
Friday 11th March 2005, 17:39
Why did you meddle with a perfectly good turbo?

The reason why it's crap is that the ECU sees intake temps climbing too high too soon, and also detects that the MAF reading is too high, hence detecting a problem, and as a result is backs things off at the top, ie retards ignition and tries to lower the boost, which is why it feels flat at the higher rpm.

Bottom line - don't tweak the wastegate unless it needs fixing.

Adam.

Giles
Friday 11th March 2005, 17:55
Why did you meddle with a perfectly good turbo?

The reason why it's crap is that the ECU sees intake temps climbing too high too soon, and also detects that the MAF reading is too high, hence detecting a problem, and as a result is backs things off at the top, ie retards ignition and tries to lower the boost, which is why it feels flat at the higher rpm.

Bottom line - don't tweak the wastegate unless it needs fixing.

Adam.

point taken.

Tallpointy
Friday 11th March 2005, 22:38
So the answer is no it doesn't raise boost above .6-.7 bar, and don't bugger about with the wastegate.

I understand the MAF/recirc/bov issue but I'm prepared to sacrifice it for the silly noise! (If I can find a bov that works for about 8.5 PSI)

Thanks all!

JUDGENINJA
Saturday 12th March 2005, 23:27
I've just fitted my turbo timer and boost guage I've kicked out 0.6 max (not for the want of trying). Is boost pressure effected by anything like oil quality, blocked air filter etc......? Or is this a signal that the Turbos on it's last legs...?

volvotuning
Sunday 13th March 2005, 01:25
Boost pressure is affected by -

1. MAF sensor
2. RPM
3. Boost control duty cycle
4. Intake Temp
5. Ignition Timing
6. Air leaks
7. Turbo condition

There are more, but it's just to give you an idea! Basically, loads of things affect the boost pressure.

Adam.

JUDGENINJA
Sunday 13th March 2005, 02:29
Cheers for that...

I think I'd better get on with the stage 0 tune and start investigating.......

I suppose theres one other possibility...the digital guage is not calibrated and could only be described as "for indication only"......