Boost Stability Problem...

1. Simop Administrator Joined: Dec 2002 Warrington Posts: 20561 Blue Saxo VTS Turbo/White Megane F1 R26

   #1 13th May 2005, 23:28

   After some advice guys, so I can fix an issue tomorrow...
   
   Last night my boost delivery started to become erratic.
   
   If I acclerate moderately, my boost now spikes well above the desired boost level... so Im not using the loud pedal.
   
   On moderate acceleration, just enough to create a steady boost level, the boost now cycles... say +0.4 bar, then down to 0.2, to zero, then up again.
   
   Sounds like a boost control problem...
   
   My thoughts currently are: -
   
   - Dodgy Apexi AVC/R solenoid.
   - Hole/split in a boost pipe, or in the control pipe from compressor to actuator
   - sticking waste gate
   - sticking actuator
   - knackered turbo
   
   I want to spend as little time fixing this tomorrow as possible, so please post up your thoughts...
   
   Cheers,
2. user_3656 Saxperience Addict Joined: Aug 2004 Herts. N/W London Posts: 13578 Project MK4 MoreDoor

   #2 14th May 2005, 00:10

   my moneys on boost piping.
   Prob easiest to check aswell ??
3. supersav Regular Poster Joined: Mar 2003 walton on thames Posts: 287

   #3 14th May 2005, 00:20

   "If I acclerate moderately, my boost now spikes well above the desired boost level... so Im not using the loud pedal.
   
   On moderate acceleration, just enough to create a steady boost level, the boost now cycles... say +0.4 bar, then down to 0.2, to zero, then up again."
   
   So +0.4 is more than your set limit??
   
   Pete
4. wideboy Saxperience Forum Bum Joined: Dec 2004 Dumfries, Scotland Posts: 4256 An S, an R, and an E46 Schnitzer

   #4 14th May 2005, 00:20

   is there any difference in the note of the engine? or can hear anything strange whilst accelerating..?
   
   my thoughts r the piping too, altho it cud b a mixture and ur turbo cud b wrecked or on its way out!
   
   give gmc a ring or email them - theyv prob got a decent idea
5. Sean Saxperience Post Whore Joined: Feb 2005 St Andrews United Kingdom (Scotland) Posts: 7384 Green mk1 vtr/s and Focus zetec

   #5 14th May 2005, 02:36

   if the boost is spiking above your preset boost level,then i doubt it'd be the boost pipes, as any fault with these would lose boost and not gain it.it sounds like a faulty actuator.
6. user_3656 Saxperience Addict Joined: Aug 2004 Herts. N/W London Posts: 13578 Project MK4 MoreDoor

   #6 14th May 2005, 02:45

   ^^ or compressor...
7. Sean Saxperience Post Whore Joined: Feb 2005 St Andrews United Kingdom (Scotland) Posts: 7384 Green mk1 vtr/s and Focus zetec

   #7 14th May 2005, 02:56

   the fact the boost is fluctuating (sp) makes me think that the actuator spring is fcuked, therefor holding and releasing boost at random.also, if the boost pipe is removed at the turbo, you can usually look inside the turbo, or stick a finger inside to feel for any movement/damage on the compressor wheel.
8. Simop Administrator Joined: Dec 2002 Warrington Posts: 20561 Blue Saxo VTS Turbo/White Megane F1 R26

   #8 14th May 2005, 03:22

   Not particularlt fussed ig the blower is knackered... but I dont think its that.
   
   Its a pressure control problem, so realistically must be the actuator, or the pressure control pipe from the compressor to the actuator... or the apexi blead solenoid.
   
   Will take a look tomorrow... Fingers crossed it s the simplest
9. GreenSaxo Saxperience Addict Joined: Dec 2002 Ashford, Kent, United Kingdom (England) Posts: 12835 Cammed Saxo "desire" 16v

   #9 14th May 2005, 03:37

   just like to point out... i didnt break it!!
   
   hope its easily fixed
   
10. saxx Saxperience Post Whore Joined: May 2005 Yeovil United Kingdom (England) Posts: 9202 A4 S Line SE 170

    #10 14th May 2005, 04:13

    can i just point out ive no idea what any of u have said!!!
    
    i hope u can fix it easily tho
11. GreenSaxo Saxperience Addict Joined: Dec 2002 Ashford, Kent, United Kingdom (England) Posts: 12835 Cammed Saxo "desire" 16v

    #11 14th May 2005, 04:22

    i could explain if you wanted..
12. saxx Saxperience Post Whore Joined: May 2005 Yeovil United Kingdom (England) Posts: 9202 A4 S Line SE 170

    #12 14th May 2005, 04:27

    u could but it could b a very lengthy process lol
13. Scottp Administrator Joined: Dec 2002 Glasgow United Kingdom (Scotland) Posts: 26097 Chelski Traktor

    #13 14th May 2005, 06:40

    actuator or wastegate i would imagine?
14. Simop Administrator Joined: Dec 2002 Warrington Posts: 20561 Blue Saxo VTS Turbo/White Megane F1 R26

    #14 14th May 2005, 23:34

    Linked Apexi solenoid out of the loop and still the same... blady thing is producing 1.5bar under load at 2800rpm
    
    Its booked in for a new actuator on Monday.
    
    Knew something would go wrong just before FCS!
15. Dan Saxperience Hardcore! Joined: Dec 2003 Middlesbrough United Kingdom (England) Posts: 23676 Seat Leon FR

    #15 15th May 2005, 00:19

    thats unlucky simo, hope it gets sorted ok.
16. Simop Administrator Joined: Dec 2002 Warrington Posts: 20561 Blue Saxo VTS Turbo/White Megane F1 R26

    #16 15th May 2005, 18:03

    Yeah, it'll be OK.
    
    Hardest thing will be tracking down the correct actuator, as this turbo was a bit of a hybrid
    
    Im having the Apexi AVC/R setup to run 0.75 and 1bar boost maps at the same time
    
    It's all good.
    
    Ofcourse, I will be sending the invoice to Mister Bidwell
17. Dan Saxperience Hardcore! Joined: Dec 2003 Middlesbrough United Kingdom (England) Posts: 23676 Seat Leon FR

    #17 15th May 2005, 22:45

    of course!