Intermittent boost
Discussion
Hi guys,
I wrote recently saying that I had lost boost, strangely it came back, today, its gone away on holiday.
I checked the actuators and they seem to push back OK with some amount of pressure and still no boost. they are definitely still connected and the little cir clip has not rotted away.
All the pipes seem OK and I'm guessing that would not be the problem anyway as the boost went and came back. I'm a little at a loss.
Any ideas gratefully received
Andy
I wrote recently saying that I had lost boost, strangely it came back, today, its gone away on holiday.
I checked the actuators and they seem to push back OK with some amount of pressure and still no boost. they are definitely still connected and the little cir clip has not rotted away.
All the pipes seem OK and I'm guessing that would not be the problem anyway as the boost went and came back. I'm a little at a loss.
Any ideas gratefully received
Andy
ok so you have zero boost... That rules out the air temp sensor as it would only cut to waste gate so 0.3.
Fact it came back is strange, as it really sounds like you have a leak, but that wouldn't usually be as intermittent.
Does the car attempt to make any boost at all even for the briefest moment, or it simply just flat?
Fact it came back is strange, as it really sounds like you have a leak, but that wouldn't usually be as intermittent.
Does the car attempt to make any boost at all even for the briefest moment, or it simply just flat?
Thoughts;
Wastegate spring is faulty, or the wastegate actuator is sticky (stuck open)?
Are the gates fully shut- ie are the actuators pushing on the gates to keep them hard shut?
Maybe a big enough exhaust leak would prevent boost from building, but you'd probably notice a leak big enough to cause it.
Finally, does it feel down on power. I know it sounds obvious, but if it feels ok then maybe the gauge is faulty or the pipe to it is kinked!
(pretty sure it's air operated not electric?).
Wastegate spring is faulty, or the wastegate actuator is sticky (stuck open)?
Are the gates fully shut- ie are the actuators pushing on the gates to keep them hard shut?
Maybe a big enough exhaust leak would prevent boost from building, but you'd probably notice a leak big enough to cause it.
Finally, does it feel down on power. I know it sounds obvious, but if it feels ok then maybe the gauge is faulty or the pipe to it is kinked!
(pretty sure it's air operated not electric?).
Edited by Green3R on Monday 24th August 13:42
My view is that you have an air leak somewhere. I know that doesn't explain why it went away and then came back but that's the simplest check to do first. Inspect the plastic inlet manifold as they've been known to crack and blow holes out and the intercooler can spring a leak too so look around the welded seams for gaping holes.
If you're absolutely certain you don't have a huge leak then check the actuators by attaching the big li-lo valve thingy to a bike pump and inflating the diaphragm of each actuator. You only need 0.3Bar to operate a standard actuator and up to 0.7 for uprated versions so don't go pumping it like the wife's been away for a fortnight or you won't have a happy ending.
If you're still drawing a blank then I have heard stories of wastegate pennies rattling themselves from their mountings but again doesn't really explain the gone-back-gone situation.
If you're absolutely certain you don't have a huge leak then check the actuators by attaching the big li-lo valve thingy to a bike pump and inflating the diaphragm of each actuator. You only need 0.3Bar to operate a standard actuator and up to 0.7 for uprated versions so don't go pumping it like the wife's been away for a fortnight or you won't have a happy ending.
If you're still drawing a blank then I have heard stories of wastegate pennies rattling themselves from their mountings but again doesn't really explain the gone-back-gone situation.
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