AMF TURBO, advice needed

I've just ordered some jubilee clips to put on the pipe that goes to the actuator because it's pneumatic and not vacuum I'll put them where the rubber pipes meets the hard thin plastic because when i put pressure from a pump through that pipe it seems to be not sealing fully and there new pipes.

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be carefull getting the correct vacumme pipes too as there are 3 different sized pipes used , it was 3mm , 3.5mm and 4mm rubber cotton overbraided pipes needed to replace all the valves pipework , and even though the 3mm stuff looks too small it does push on the hard plastic pipes

N02-035-35 was the N75 vaccume pipe 3mm

another weak point ive found is the outlet on the N75 valve has a rubber 90degree elbow pushed on one of the outlets , i throw this away and use a slightly longer peice of vaccume pipe and plumb straight onto the N75 as found these always weap very slightly which would be enough to cause limp mode
 
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justjust73 said:
I've just ordered some jubilee clips to put on the pipe that goes to the actuator because it's pneumatic and not vacuum I'll put them where the rubber pipes meets the hard thin plastic because when i put pressure from a pump through that pipe it seems to be not sealing fully and there new pipes.
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I think you'll find that it's vacuum not pressure. There is a vacuum pump on the end of camshaft but no air compressor.

RAB
 
Trust me it's pneumatic put a vacuum pump on it and the actuator goes nowhere attach a pump up to 25 psi and actuator opens,i used 3mm hose to replace.

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That's because the waste gate's job is to release the over pressure from the turbo, otherwise the engine would over revved to pieces.
 
justjust73 said:
1.2 tdi and 1.4 90 is vacuum 1.4 75 is pneumatic
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That's correct. The variable nozzle turbos used on the 1.2 TDI and the TDI90 use vacuum to alter the angle of the nozzles, whereas the wastegate turbo used on both variants of the TDI75 (AMF and BHC) use pneumatic pressure to open the wastegate. The pneumatic pressure required to open the wastegate comes from the compressor wheel of the turbo itself.

Cheers,

Tom
 
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theres 3 pipes that go to the N75 , one connects to the top of main inlet pipe feeding the turbo, so it has suction , the next one connects to the turbo outlet pipe , small 11mm bolt with a outlet pipe so it has air pressure, then the last pipe goes onto the wastegate actuator , , the N75 is feed about 20psi from the turbo outlet , "boost pressure" this is used to open the actuator ... so the slightest of leaks on these vacumme pipes will have the dreaded limp mode as it takes all the 20 psi or so to fully open the wastegate as it has a mighty spring inside the actuator,
 
JIGSAW said:
theres 3 pipes that go to the N75 , one connects to the top of main inlet pipe feeding the turbo, so it has suction , the next one connects to the turbo outlet pipe , small 11mm bolt with a outlet pipe so it has air pressure, then the last pipe goes onto the wastegate actuator , , the N75 is feed about 20psi from the turbo outlet , "boost pressure" this is used to open the actuator ... so the slightest of leaks on these vacumme pipes will have the dreaded limp mode as it takes all the 20 psi or so to fully open the wastegate as it has a mighty spring inside the actuator,
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Very nice explanation, but does it fit the symptoms described in post #20?
 
timmus said:
You're forgiven as you know a lot about a model of A2 that most people here know very little about. :)
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Hi Tom,

That does beg the question of why 1.4Tdi's have a tandem pump?

RAB
 
RAB said:
Hi Tom,

That does beg the question of why 1.4Tdi's have a tandem pump?

RAB
Click to expand...

Vacuum is still used for the EGR valve, the brakes and the anti-shudder valve (AMF only; BHC has an electronic ASV).

Cheers,

Tom
 
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