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Discussion Starter · #1 ·
guys new to the forum and from what i see i think it is very good.
i have a 01 tdi golf with the alh engine.
i work in a truck garage and a mate put the car on the diagnostics machine in a skooda garage and told me the fault was sporadic overboosting.
The car cuts itself back when u really drive it hard when it is cold. never does when it is hot tho.
i changed the vacuam solenoid on the bulkhead which controls the wastegate and thought it made a difference for a while but the prob has bow returned. i also put an air mass meter on it just incase..
only 50k mile on it now, and i got it with 21k and its beeen doing it from the start. smart arse i bought it off had it well warm when i looked at it..!!
thanks for any help ya give.
 

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If you look at the wastegate actuator, the rod from it, is parallel to the exhaust houseing. If so , this is a VNT type. These have a problem, in that the stick in the max-boost position. When the MAP sensor, sense's this, the power is backed off.

If the rod is parallel to the centre line of the turbo it is a standard type.

John
 

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What effect did the over boosting have on it? What I mean is, apart from the diagnostic how did u know it was doing it?

After I got my PD 130 golf remapped, when I started it from cold I got a fair bit of clutch slip at certain revs. This stopped happening once the engine had warmed up.

Do you think it's possible that the car could be remapped and the guy u bought it from didn't tell you?

Henry
 

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Discussion Starter · #8 ·
to be hoinest that thought had crossed my mind as it is a donegal car!!
no clutch slip. i nhad thight of gettin it chipped. wonderd if it would increase the boost tolerances... if they new engine parameters would accept the higher boost..
had a thought that it colud be some prob with the boost presssure sensor..
 

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Discussion Starter · #10 ·
sorry did not get a chance to look at it today.. was flat out all day and was dark when i got home, will look 2mrw and get back to ya. thanx
 

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Discussion Starter · #11 ·
looked at it and from what i can gather it seems to be vnt type. the wastgate rod is at 90degrees to the turbo shaft..
the reason i'm tryin to get to the bottom of it now is that i feel the car is under performing at the mo. i dont drive it hard til it is warmed up, which is a good thing i know, so the over boost dosent really occour that much, if it is under boosting will i get a fault code?? no lights on the dash and i have checked the tank unit and changed the fuel filter too..
 

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Disconnect the actuator rod from the little lever and try and move it up and down, i'll bet it is stuck. I've freed them out before by removeing the hose that goes to the actuator and pressurizeing it with less the 10 psi from and airline, but be carefull.

John
 

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Discussion Starter · #13 ·
Was away for a dirty weekend...
now i'm cak to reality i'll try that and let ye know how i get on... thanx for the help.
 

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Discussion Starter · #14 ·
right checked that.. un fortunatly the car was warm at the time, using a vacuam pump i can see it is movin free. there is a per vac from the valve at tickover of 17.5 hg and about 5hg at 3000 rpm, is that about right??
could it be whatever senses the boost pressure?
 

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Discussion Starter · #16 ·
i'm afraid i have to disagree with you, pressure does movbe the rod, but the pressure must be measured, then the vacum system is used by a solenoid on the bulkhead which controls the vacum supplide to the actuator. iv had a gauge on it and there id definetly a vacuam and not positve pressure there.
 

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Pressure moves the rod from the actuator to the VNT mechanisim to control the boost. When you check the pressure/vacum at idle, it will be a vacum as the turbo is not spinning fast enough to generate boost pressure.

If the the rod moves as pressure is applied to the actuator, the you VNT mechanisim is probobly ok.

John
 

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If it is the varible vane turbo and u changed the solenoid and boost pressure sensor
and still no joy then it is the turbo. We had to fit a few of those turbo's on 110bhp passats and golfs.
 

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Discussion Starter · #19 ·
well i didnt change the boost sensor yet, was only askin if anyone has heard of a faulty one before..
its the 90 hp alh engine in mine...
anyone know how much is a turbo

is it worth my while to fita different one if it comes to that.. like a 130hp turbo... r they different??
 
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