Torque Cars

ECU cuts the turbo in 1st gear at 5700 RPM

Discussion in 'A3/S3/RS3' started by djuka, 10 September 2013.

  1. djuka

    djuka Full member

    Messages:
    10
    From:
    Serbia, Belgrade
    Car:
    Audi S3
    I have had the car for a months since the upgrade. The first month is was running sweet but a few days ago it started shuting the turbo in 1st gear when I speedup at around 5700-5800 RPM. Is annoying especially when you are in the middle of a race.

    When hooked to a PC everything is OK. Any ideas what could be the culprit?
     
    Last edited: 10 September 2013
  2. MattsCar

    MattsCar Tuner

    Messages:
    67
    From:
    UK, Shaftesbury
    Car:
    96,2.0 Renault Clio
    actuator?
     
  3. davalav

    davalav Moderator

    Messages:
    3,617
    From:
    Essex, England
    Car:
    Mini Cooper S R56
    Loose boost hoses?
     
  4. obi_waynne

    obi_waynne Administrator Staff Member Moderator

    Messages:
    41,346
    From:
    Deal, Kent UK
    Car:
    A3 1.4 TFSI 150 COD
    Sounds like the "overboost safety" is cutting in as it's detecting overboost. A remap should help with this.

    What mods have been carried out? This sort of thing is typical of fitting a larger turbo or running higher boost. The standard ECU just doesn't like too much boost and cuts it for protection.
     
  5. djuka

    djuka Full member

    Messages:
    10
    From:
    Serbia, Belgrade
    Car:
    Audi S3
    Thank you for your post.

    Car history:
    Engine was rebuilt since it seized and the car was not moving on its own power when purchased. All hoses replaced. Iridium NGK spark plugs. Has a larger hybrid turbo, 630cc injectors, larger fuel pump, larger exhaust pipes (68mm), catalysators removed. ECU remapped for 265-280HP map. Map asks for 1.5 bars of pressure in 1st gear (seen on PC when hooked on car ECU). As to be safe, changed the spark plugs with new ones. Replaced battery 650Ah with 750Ah since a friend told me that he had a problem with the fuel pump not able to sustain power and would cut off for an instance due to a smaller capacity battery.

    Two days ago at local dragstrip, the "cut" dissappeared. This time in 1st gear went all the way to 6300 RPM and no "cuts" appeared. Its colder now (22C) so I still might have the problem when the weather temperature is hotter (30C when there was a problem).

    Since I bought the car in this state (remaped with all the extras) I'm still in the process of finding out the specifications of all parts that were added. Last info, mapper is from UK but don't know which one.
     
  6. obi_waynne

    obi_waynne Administrator Staff Member Moderator

    Messages:
    41,346
    From:
    Deal, Kent UK
    Car:
    A3 1.4 TFSI 150 COD
    I wonder if it was mapped for Super unleaded then. If temperature makes a difference then this is a big clue, detonation or running lean could be the issue.

    What fuel do you use?
     
  7. djuka

    djuka Full member

    Messages:
    10
    From:
    Serbia, Belgrade
    Car:
    Audi S3
    Unleaded 98

    It was remapped last time in Spring so the temperatures were similar to what they are now.

    Yesterday I did a couple of duels and everything works fine but I noticed something, when in neutral and idling after a couple of accelerations in the 6000 RPM range, idling isn't smooth. The revs go up and down for a minute before settling.
     
  8. wigguy1

    wigguy1 Wrench Pro

    Messages:
    47
    From:
    holden, mo.,USA
    Car:
    84,944porsche,400hp
    I don't know how it would affect the turbo but the idle surging could be a vacuum problem. Start simple and cheap, a vacuum pump is cheap.
     
  9. SLEEPER

    SLEEPER Pro Tuner

    Messages:
    2,783
    You said "remapped for 265-280 bhp"

    With the greatest respect that does not sound like a proper map to me.

    Do you mean chipped , tweaked , adding a map that is supposed to be the right one or or a proper map on a dyno with an ecu you can alter ?
    If it isn't the last one that is most likely your problem.

    There is a difference between actual boost and set boost. When it is colder it is possible to run more boost unless it has a very sophisticated ecu with extra sensors.

    And seeing something on a static pc isn't the same as when under load in first gear.
     
    Last edited: 17 September 2013
  10. SLEEPER

    SLEEPER Pro Tuner

    Messages:
    2,783
    Also
    Do you have a boost controller fitted and/or an accurate boost gauge fitted or even any boost gauge at all. And is it the stock ecu ?
    Also the fulll engine spec would help

    it is much easier to diagnose a problem with the information But as Wayne says it sounds like the ecu is cutting out when the set maximum boost level is reached

    Incedently Engines will always reach higher boost in lower gears quicker so that is where over boosting will happen first
     
    Last edited: 17 September 2013
  11. djuka

    djuka Full member

    Messages:
    10
    From:
    Serbia, Belgrade
    Car:
    Audi S3
    The car was first just chipped. Then the former owner was not satisfied with the result so he fitted a larger fuel pump, 630cc injectors, KN filter, new exhaust system and with that he went to a mapper with a dyno where the factory ECU was remapped to a custom map for the car in that state. I contacted the mapper and he told me that he had problems and wanted to quit but the former owner insisted on the remap. He told me that he could could only achieve 265HP consistence but I could axpect boost to 280 when the weather was colder.
    The reason I can't go to the mapper at this time is because he is 600km away.

    We (an Audi service man and me) tested the car under full load in all gears with the laptop connected during the drive. We saw that the set boost was 1,5 bar for 1st gear and that was unusaual thus the explanation. The Audi guy told me he doesn't know where to look because his PC tells him that everything is OK, and for him to look means I have to install the original Audi Factory settings ECU which I don't have but am looking to buy a second hand one.

    The S3 has this engine even though its an October 2002 model,

    *Removed URL as per our T&C's*
     
    Last edited: 21 September 2013
  12. djuka

    djuka Full member

    Messages:
    10
    From:
    Serbia, Belgrade
    Car:
    Audi S3
    The S3 has 210HP engine even though its a October 2002 model. It was sitting in the showroom for a year before it was sold.

    *Removed URL as per our T&C's*
     
  13. djuka

    djuka Full member

    Messages:
    10
    From:
    Serbia, Belgrade
    Car:
    Audi S3
    Also I forgot to say that the cars turbo had an upgrade to a larger hybrid turbo, although I don't know which one yet but will have this information soon since I will have a meet with the previous owner tomorrow.
     
  14. T9 man

    T9 man TC Pro Founder Moderator

    Messages:
    20,369
    From:
    London, UK
    Car:
    Saab 9-3SS T9
    You have now reached 10 posts djuka so you are now officially able to post up URL's and photos :)
     
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