passat 90bhp tdi question

stoneyfordNI

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Jan 9, 2005
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Lisburn NI
just been out for a drive with a friend , who has just bought a 255k miles passat 90 tdi , he was saying theres little pull up top ,

codes ,

coolant sensor ( gauge always on zero)
boost intermittant minus deviation or something

we logged airmass and all seemed ok , met specifed values across the board , BUT

boost pressure was down , was specifying 1836mBAR peak but was only getting 1067mBAR , and was lower right across the rev range , (block 11 i think)


any1 wanna give me any ideas , does the coolant sensor play a part in this ,

cheers in advance

stephen

EDIT: no whooshy boost leaks either
 
Last edited:

m0rk

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May 19, 2001
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Clanfield, UK
it's not making any boost then? sounds like something like the wastegate is stuck open or something
 

stoneyfordNI

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Jan 9, 2005
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sounds like new turbo time , what causes it to stick ( miles and soot) can it be loosened up , what controls the actuator on these barges (N75) ,

so many questions
 

m0rk

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May 19, 2001
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probably right, 2nd hand tubby's are cheap

N75 should control, but no good if the thing is buggered
 

basstard

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Aug 24, 2002
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is this the wastegated or VNT model? 90hp came out in both guises,,,

as in a very recent thread in the tdi section it's possible too that the EGR is stuck open and won't let any boost or that something throws it into limp mode [hence the boost deviation code].
Check all IC tubings, check all vacuum hoses, try a spray cleaner can into the intake [sintoflon, 10k diesel cleaner or whatever else].
plus, the coolant sensor thing in which block is? cos it's very common it being the coolant temp gauge in the instrument block and not the coolant sensor in the engine block. if it's the coolant sensor, go out and buy one, kinda cheap.

you can do an output test of the N75, in the engine block select the 'output tests' button at bottom right [IIRC] of the screen. when it comes to N75 you should hear a light click coming from it [you'll obviously need to do this with the engine off!!!].

let us know what you come up with and next time better post in the tdi section.
 

stoneyfordNI

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Jan 9, 2005
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Lisburn NI
thanks for the help peoples , i take it i can trace the vac tubing off the actuator to the N75 , where is the N18 in relation to this ( wat does it do) ,
 

basstard

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Aug 24, 2002
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stoneyfordNI said:
thanks for the help peoples , i take it i can trace the vac tubing off the actuator to the N75 , where is the N18 in relation to this ( wat does it do) ,

N75 has a white cap and is located on the firewall under the windscreen,,, just a few centimeters on its right [your left] there's an identically shaped valve with black cap,,, that's the N18, it controls the EGR valve,,,
 

m00k

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ok it is actually my car that has the problems

thanks for postin it up for me lad

seems when u start the car the turbo runs ok(ish) altho i still dont think it pulls as it should, but as u drive the turbo will completely cut out, but if u put it in neutral or put the clutch in an turn engine off and on then the turbo will run again for a while?

anyone else any ideas wat this wud be? surely if the turbo was on its way out it would not spin up as often as this?
 

m00k

Guest
sorted :D

wit 255k on it the egr valve was coked up and stickin, so free'd it up an made sure it was closin properly, then removed the hose and blocked it up, runnin 100% now :D