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inconsistant boost

Discussion in 'A3/S3 Forum (8L Chassis)' started by Adam Davis, Aug 31, 2012.

  1. Adam Davis
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    Adam Davis Member

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    [Aug 31, 2012]
    Hi guys, ive tried finding the answer to this specific problem but i cant find it. Sometimes when i hit full boost, it will peak at 0.9 of a bar, creep up to 1.1 with rpm and then tail off like normal. Other times it
    willl peak straight to 1.1-1.2 and then tail off. Whats your opinions on this?? Would you put it down to tired n75 or maf?? I was going to change both. Its stage 1 revo
    Thanks
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  3. badger5
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    [Aug 31, 2012]
    its low for revo, unless the revo settings are low..
    what are the settings?
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  4. Adam Davis
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    Adam Davis Member

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    [Aug 31, 2012]
    Thanks for the reply. I dont know what the settings are. I forgot to mention its an agu. I thought 1.1-1.2 is normal for this engine??
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  5. STEALTHQUATTRO
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    STEALTHQUATTRO Member

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    [Sep 2, 2012]
    hi guys really sorry for hijacking your threds, am bit new on here and dint have a clue how to start my own!
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  6. Adam Davis
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    Adam Davis Member

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  7. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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    [Sep 14, 2012]
    Scan for fault codes and do some airflow logs in VCDS

    <tuffty/>
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  8. STEALTHQUATTRO
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    STEALTHQUATTRO Member

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    [Sep 14, 2012]
    Don't worry mate! I did the same last week :p
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  9. Adam Davis
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    [Sep 17, 2012]
    Right no fault codes. I cant data log on vas at work so used live readigs. I got 145 g/s on maf, 77% duty on n75 which shows my tubby aint working flat out so hopefully OK. I couldnt find a boost leak, bearing in mind i havnt used a boost leak tester, just visual inspection of all pipes/vac lines, also boost gauge sits at 0.7 of a bar on idle. What other blocks will be useful to log? can you log requested/actual boost? i used 006 for fuel trims but i dont think it is correct, as im not sure it can be logged on agu?! but i am uncertain what parameters the ecu uses to adjust fuelling, is it just narrowband lambda?
    When driving recently it boosts to about 0.8 of a bar at 2500 rpm, then creeps to 1 at 3k. WOT at 3k it just goes straight to a bar, no spiking which i come to expect on a k03.
    Thats all the information ive gathered so far. and help would be great.
    thanks
    Last edited: Sep 17, 2012
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  10. Adam Davis
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  11. Adam Davis
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    Adam Davis Member

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    [Sep 24, 2012]
    Right since the colder weather has kicked in it now doesnt even boost to a bar. 0.8 then creeps to 0.9 :( feels slow as **** lol.the n75 duty seems real low. Would the low n75 readings be becuse the maf is nackered?? or would it be low maf readings because the n75 is gone? If u get my drift lol.
    Last edited: Sep 24, 2012
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  12. Adam Davis
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    Adam Davis Member

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    [Sep 24, 2012]
    Just pulled actuator pipe off, 1.2 bar :s knackered turbo??!!
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  13. badger5
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    [Sep 25, 2012]
    what a max of 1.2bar?
    @ >5krpm, pseudo in the ball park of normal, but i would expect a big spike on initial spool
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  14. Adam Davis
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    Adam Davis Member

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    [Sep 26, 2012]
    Peaked at about 1.3, but my car has never spiked thats what i find weird. Now it shoots to 0.8 and creeps up to 1bar . Can the boost settings be altered on the revo map for an agu?? Whats the max boost i can run on the map as i might plumb in a mbc. Is the map just over conservative?? Cuz my maf readings are low also.
    Thanks for your input bill
    Last edited: Sep 26, 2012
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  15. Adam Davis
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    Adam Davis Member

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    [Sep 26, 2012]
    Ive made a boost leak tester and am going to try that tomorrow also.
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  16. badger5
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    [Sep 26, 2012]
    revo not adjustable on agu.
    low maf readings may be a cause not a symptum as me3.8 ecu is very dependant on airflow measurements
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  17. Adam Davis
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    [Sep 27, 2012]
    Well......my boost leak tester worked a treat!! I thought i didnt have any but i found a split pipe and all my injector seals are leaking. Waiting for o rings arriving tomorrow and bought new seats that sit in the inlet manifold. At 1.1 bar now and thats just from the split pipe.
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  18. cabrio boy
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    cabrio boy Member

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    [Sep 27, 2012]
    Adam how did you make you boost leek tester I've the same problem with mine ?....
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