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boost gauge help
by
con
on 21 May, 2007 04:43
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Just installed my boost gauge to my 91 golf 1.6 TD. Tapped the hose that runs from inlet manifold to LDA, fed the tube into the dash and hooked up the gauge. But when I start the car the needle doesnt move, it just vibrates at the 0 position. when I rev the car it moves down to the negative bar a tiny bit and thats it. Now when I say it moves I mean it creeps back a millimetre on the gauge. What have I dont wrong? I hope the gauge isn't broken.
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#1
by
jimfoo
on 21 May, 2007 05:41
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Sounds like the gauge is hosed to me. If you pull the hose off the back of the gauge and rev the engine a bit, does the air coming from the hose increase any? You won't get any reading at idle btw. I guess another question is depending on what turbo you have, it may not make much boost with a quick rev. Drive it and get into the throttle to see if it does anything.
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#2
by
jimfoo
on 21 May, 2007 07:27
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As Jimfoo said, most turbos won't produce any boost unless under load or severely revved.
Andrew
Well, maybe if it's a VNT :wink:
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#3
by
con
on 21 May, 2007 09:32
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Thanks for the help, I'll take it for a drive and see, thanks!
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#4
by
Vincent Waldon
on 21 May, 2007 11:12
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I'll bet a gazzillion dollars as soon as you give it a load in third gear and put your foot into it you're going to see boost. You won't see hardly any in first gear, and for sure nothing sitting in neutral.
Made me panic a bit the first time I installed a boost gauge as well... I can hear the turbo, why no boost ?? Then I thought a bit about how turbos really work and what boost really is and headed for the highway.
Vince
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#5
by
jimfoo
on 21 May, 2007 11:25
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Depends on the turbo. My k14 would make a little boost revving in neutral, and would make full boost in 2nd(my first) and on up, but I can see a bigger one needing more time to spool.
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#6
by
Vincent Waldon
on 21 May, 2007 11:37
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Good point. He's got a 91 so likely a Garrett T3 ?? If so... no boost in neutral or even in first gear really... if it's anything like mine, with stock fueling.
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#7
by
numbnuts
on 01 Jun, 2008 06:41
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Thought i would bring this up again as i have installed a boost gauge today on my mk3 aaz and only managed a 1st gear run up the hill but was getting -0.2bar on the gauge. :? should i be looking for a restriction or is this normal? I have never heard the turbo whistling on this thing by the way :cry:
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#8
by
Vincent Waldon
on 01 Jun, 2008 07:38
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Sadly this doesn't sound normal... the usual next step here is to pull the air intake hose leading to the turbo and see if you can (gently) spin the impeller by hand. If so, then fire up the engine and see if it spins.
A negative boost pressure sounds like no turbo... and depending on how negative also a restriction in the intake... dirty air filter ?? Mouse nest ??!!
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#9
by
numbnuts
on 01 Jun, 2008 09:34
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:cry: i'll have a look :cry:
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#10
by
numbnuts
on 01 Jun, 2008 12:26
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So if my turbo's nackered, what are my options? I have been on the lookout fro a T3 setup for a while but to no avail. Can i get a rebuild kit for the k03 i presume i have? :?
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#11
by
Vincent Waldon
on 01 Jun, 2008 14:14
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#12
by
numbnuts
on 02 Jun, 2008 12:29
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Well i popped off the hoses and the turbo spins freely although there doesn't feel like much pressure coming out of the turbo, not in comparison with the demand for the engine into the inlet manifold. i have put the boost gauge hose into the pipe from the inlet manifold to the lda? where the aneroid pin sits. but it still read negative pressue on idle and whilst revving it :? the wastegate is free to move also, so i am stuck
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#13
by
jimfoo
on 02 Jun, 2008 13:41
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It won't make much until the engine gets lots of fuel. Maybe your wastegate could be stuck open as well. That would cause a lack of boost, though I don't know about negative pressure. You absolutely sure there are no restrictions anywhere before the turbo and that the filter is clean?
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#14
by
Vincent Waldon
on 02 Jun, 2008 14:07
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i have put the boost gauge hose into the pipe from the inlet manifold to the lda? where the aneroid pin sits. but it still read negative pressue on idle and whilst revving it :?
That's the right spot for the gauge.
By "reving it" do you mean in the driveway or on the M5 ??!!!
You will get little or no boost without the engine under load. The Bentley test says something along the lines of 3rd gear on the highway at about 3000 RPM going up a steep incline... something that makes the engine work. First gear is too easy on the engine, and the transition thru second is pretty quick.