Overboosting

**wrinx** · 22-04-09, 16:36

Not spiking...but consistently high boost...wastegate sticking or not working properly?

I've turned the MBC right down so it's actually off now, and still managing 1.2-1.3bar boost....it's very nice, but?

Also wondered if I'd connected the turbo pipes the wrong way around...any other ideas?

wrinx

**arjunior45** · 22-04-09, 16:51

Pierburg valve connections? are they correct?

Nick

**AlfaJack** · 22-04-09, 17:16

I think the wastegate arm is non adjustable so perhaps the diapram may have worn out....just throwing ideas around.

Can you join the two hoses together? I think you will then get base boost - this will say if the wastegate is ok. Probably just the controller not allowing enough air from one side to the other.

**wrinx** · 22-04-09, 18:13

Originally Posted by arjunior45

Pierburg valve connections? are they correct?

Nick

Not using it, Manual Boost Controller is there instead

wrinx

**wrinx** · 22-04-09, 18:15

Originally Posted by AlfaJack

I think the wastegate arm is non adjustable so perhaps the diapram may have worn out....just throwing ideas around.

Can you join the two hoses together? I think you will then get base boost - this will say if the wastegate is ok. Probably just the controller not allowing enough air from one side to the other.

Will try that...

I recently read somewhere that if the hoses are connected the wrong way around the boost isn't controlled at all...but I'm sure they're right as I was careful not to mix them up

wrinx

**AlfaJack** · 22-04-09, 18:59

Originally Posted by wrinx

Will try that...

I recently read somewhere that if the hoses are connected the wrong way around the boost isn't controlled at all...but I'm sure they're right as I was careful not to mix them up

wrinx

Yes that should be right otherwise the line that needs air pressure from the turbo to push against the ball and spring will be from the wastegate diaphragm. In this case the air going in to the valve in the wrong connection would probably be blocked there as the spring will hold it shut until its gets pressure from the other side - that will cause the overboost - if this is the case and the wastegate is not opening at all then you would probably be hitting the 1.5 limit

**Brul(tm)** · 22-04-09, 20:13

Originally Posted by AlfaJack

and the wastegate is not opening at all then you would probably be hitting the 1.5 limit

Oh YES, no troubles at all! Been there, done that and experienced it

You will get fuel cuts and it will be a bit difficult to drive the car. You need a very lightweight feet

Greetings,
Marc

**AlfaJack** · 22-04-09, 20:41

Originally Posted by Brul(tm)

Oh YES, no troubles at all! Been there, done that and experienced it

You will get fuel cuts and it will be a bit difficult to drive the car. You need a very lightweight feet

Greetings,
Marc

The classic Q4 brown trouser moment!

**wrinx** · 22-04-09, 21:31

I thought I saw nearly 2bar on the gauge the other day (before I knew there is a problem) and controlled it after that....not sure if that's possible???

No fuel cut off either!

wrinx

**AlfaJack** · 22-04-09, 21:51

Originally Posted by wrinx

I thought I saw nearly 2bar on the gauge the other day (before I knew there is a problem) and controlled it after that....not sure if that's possible???

No fuel cut off either!

wrinx

As soon as the map sensor detects 1.5 bar it should throw the fuel cut

**wrinx** · 22-04-09, 22:52

Agreed..hopefully it was my usually under active imagination playing tricks on me

wrinx

**wrinx** · 25-04-09, 21:27

Originally Posted by AlfaJack

As soon as the map sensor detects 1.5 bar it should throw the fuel cut

What does that feel like? Initially I thought the clutch was slipping at higher torque levels but looks like it's at around 1.5bar...does it feel the same?

wrinx

**wrinx** · 26-04-09, 12:59

Good grief

Sorted the boost...I was adjusting it according to a picture that came with the MBC, it shows a red arrow turning left and a green arrow turning right (like a water tap).

To me that means reduce boost left and increase boost right....nope, the other way around!

Only realised when I took the MBC apart last night to check which way around the spring worked on the bearing!

...anyway, sorted now, at a reasonable 1.2bar

wrinx

**Q4Jan** · 26-04-09, 15:32

I think you are the only one who sees a red arrow as the way to reduce boost.

red as dangerous, green as in safe?

**wrinx** · 26-04-09, 18:51

Not quite...I thought green for "go", red for "stop"...but I was wrong

wrinx

**AlfaJack** · 26-04-09, 22:19

Originally Posted by wrinx

What does that feel like? Initially I thought the clutch was slipping at higher torque levels but looks like it's at around 1.5bar...does it feel the same?

wrinx

You will know when it happens. It feels like a really violent jolt and it will throw you forward a bit. I thought I had really mangled the engine when it first happened.