General Boost Solenoid Failure????

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General Boost Solenoid Failure????

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ok so I have had this issue since I got the car, turns out this car has a few issues and I am talking them 1 at a time.


Ok the issue started off like so, when on a motorway if I went to foot flat down to over take for more than a second it would through up the Engine Fault code and reduce power, reset the code and it was fine again.


But today its started with another boost issue and I think they are related, the car still drives fine and gets up to speed but I cant hear my turbo anymore and I cant feel it kick in, it just feels like an NA diesel now, although it got to speed it was noticeably slower to get there, but, there isn't an EML on or engine fault on the display.


So, I am wondering if its the boost solenoid or is it worst case and my Turbo is on its way out???
 
Perhaps it may be the egr valve unless you have that blanked off already, other thing is you can check the actuator that is operated by the boost solenoide vacum tube for any signs of movement before the bad thoughts of turbo, when my boost valve gave a little problem it did give fault indication on the dash, in my case it was due to the location and moved it to the side of the battery box which cured things, there is info in guides again if you not already done when current issue solved.
 
Cheers, no its not EGR blanked yet, it is on my list of things to do lol,


Solenoid relocation, I have heard of this, maybe I need to do it sooner rather than later lol


Cheers mate.
 
Yes solenoide relocation made big difference for myself gets it out the way from any road spray...if you have multiscan am sure you can check boost values , or check actuator movenment by the vacum tube.least you have an idea which area to look at, rather it was egr than turbo you could even remove tube from boost solenoide and check if it is causing a slight suction in case for some reason it is not giving a fault for that..the tubes do become rather brittle after time and holes or small splits in them do occur but not sure if that would throw up a fault indicator on dash, sure someone with turbo brains cells be along soon.
 
i'm going to go out tomorrow and look at moving it and I may go and get some silicone vac piping and replace it all while I am on, a friend of mine spent 4 weeks tracking down a vac leek on his Passat 1.8t, he wishes he had just replaced it all in the first place lol.
 
Ok, so I relocated the Solenoid (I think) it has a vac pipe coming from the back on the inlet and then goes to the actuator on the turbo. I relocated it up to next to the battery on the side of the head, but alas, it has made no difference.


I can drive the car fine and I can keep it out of limp mode by only using upto 90% throttle, but if I hold full throttle for more than 2-3sec it jumps into limp mode with no boost at all, normally I can hear the turbo spooling up but in limp mode there is no turbo whistle.


now this is the strange bit, if I ride the clutch I can manually spool up the turbo (its tricky with slipping the clutch and 50-75% throttle) and I can hear the turbo spool up and then the light goes out and I have full power back.


No, I still haven't blanked off the EGR.
 
have you got a code reader or software to view or log data like mes?
or anyone nearby can sort you out with the above
chances are its seeing overboost and cutting power to be safe.
have a good look at the vnt actuator and vnt arm on the turbo, make sure it has full travel, otherwise suggesting vnt vanes sticking maybe.
idle the car and pull the vac pipe off the actuator , see the rod move , push pipe back on see it move again, your looking for over approx. 10mm at least of travel, I think 13mm is max Ive seen on my 2.
 
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Ok, checked the vac pipe, on idle take it off and It pushes out about 13mm put it on and it goes back, I have a video but I'm on mobile, will upload later.

I will also put it into limp mode on my way home and get a pic of the fault code when I get home to my laptop and cable.
 
if you have it do a log of revs,desired boost actual boost and actual maf airflow.
hopefully something will show itself as not right even if a code isn't thrown.
from your description the turbo vnt parts all sound to be working as it should.
if it is overboosting its most likely the vnt solenoid unable to vent vac to the actauator.
if you start and stop the car does it still move the vnt actuator the same as when you pulled the pipe off?
and also blanking the egr next as no reason not to and will halve potential issues
 
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Ok having a real ball ache, I have had my car connected before with this cable but can't do it again, I have taken pics of everything I thought might help diagnose why I can't connect.
 

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that looks familiar sometimes mine does the same especially if I swap leads.
have to do the same thing test for interface select port and test again and recheck cable type.
had occasion in past where wasn't having it , rebooted computer and connected straight away.
 
Ok so my issues continue this morning, it appears I can connect to the ABS and Airbag Control Unit with out an issue, but I cant connect to the ECU. i'm about ready to give up with this now and sell the car. almost had enough.
 
Ok, so still can't get my laptop to connect to the ECU, I can connect the ABS and Airbag fine bit not ecu, going to order a wifi ELM 327 on Mon if not today.

But i do have a small update, I have fitted a digital Boost gauge that reads Bar, I am getting a common boost pressure of around 0.7-0.8bar but it spikes upto around 0.9-1.0 bar but only briefly, this is at 3/4 throttle, on full throttle so it goes into limp mode in 3rd gear it fluctuates between 0.5-0.9 Bar before popping into limp mode. If I keep accelerating it turns the light off and is fine again. This really is starting to do my head in now.

Oh and since I have fitted the new MAF I am now getting lots of black smoke on hard acceleration. I'm guessing that's over fueling.

Could this all be down to a dying turbo????
 
Ok, so still can't get my laptop to connect to the ECU, I can connect the ABS and Airbag fine bit not ecu, going to order a wifi ELM 327 on Mon if not today.

But i do have a small update, I have fitted a digital Boost gauge that reads Bar, I am getting a common boost pressure of around 0.7-0.8bar but it spikes upto around 0.9-1.0 bar but only briefly, this is at 3/4 throttle, on full throttle so it goes into limp mode in 3rd gear it fluctuates between 0.5-0.9 Bar before popping into limp mode. If I keep accelerating it turns the light off and is fine again. This really is starting to do my head in now.

Oh and since I have fitted the new MAF I am now getting lots of black smoke on hard acceleration. I'm guessing that's over fueling.

Could this all be down to a dying turbo????


Realy mate ? mine spikes at 2 bar... Ill get a vid on the way to work tomoow for you , gives me a excuse to hoon :)
 
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