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1.9TDI PD 130 boost problem

Discussion in 'A6/S6/Allroad forum (C5 Chassis)' started by sonix, Dec 22, 2007.

  1. sonix
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    sonix New Member

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    [Dec 22, 2007]
    I’m having some trouble with my A6 1.9TDI PD, AWX, 130HP engine, year 2002.

    It has been running very fine over the last 5 years, but know I’m having an issue with the boost control.

    Upon accelerating, the boost suddenly spikes, and gives a little kick in the back. Certainly not very healthy with a cold engine and -5 degrees outside.
    The engine does not react smoothly to pedal movements, and I’m also sometimes having a trouble code when reading out with VAGCOM:

    17964 - Charge Pressure Control: Negative Deviation
    P1556 - 35-00 - -

    After having a long run on cruise control, the car refuses to accelerate when pushing the pedal, or only a tiny bit, then it gives the trouble code.
    Looks that it does not want to accelerate due to the absence of boost. (charge pressure control valve stuck in ‘no boost’ position?)

    I’ve already checked the N75 charge pressure control solenoid valve, I measure 19 ohms (correct value according to workshop manual).
    I can move the turbocharger actuating rod, moves smoothly, but it needs quite some force to move, don’t know if this is normal.

    Anyone has an idea what else I should be looking for?
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  3. sonix
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    sonix New Member

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    [Dec 22, 2007]
    Here's a read-out of VAG scope, so you can see the actual spike when pushing the pedal gradually.

    Blue line : specified intake pressure
    Green line : actual intake pressure
    Red line: MAF

    [​IMG]

    Oh yeah; you guys might be wondering the intake pressure is quite high. The engine has been remapped ;)However, before the problem it never went above 2800 mbar, now you can see a spike even above 3000 mbar. I can even hear very clearly the boosted air rushing into the engine, which was not the case before.
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  4. sonix
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    sonix New Member

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    [Dec 27, 2007]
    Still having this problem, but can't seem to find what the problem is.

    I ran a 'basic setting' test with VAG-COM, it let's the engine accelerate to 1400 RPM, and then opens and closes the boost control valve for some seconds. I checked under the hood, and I can see the actuating rod move normally. The RPM also goes up by about 200 when the valve closes.

    Anybody who can tell me what else to look for?

    Thanks!
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  5. etronic
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    etronic TDI VCDS Map User

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    [Dec 29, 2007]
    Be carefull as your turbo will fly away soon with this such high value of pressure. If you have access to VAG please log separately (1 channel per one run) channel 1, 3, 4, 8, 11, on 3rd gear with full throttle from 1500rpm till 4500rpm. Then basic settings on idle chan. 0, 4, 11, and just on idle in normal measuring blocks chan 13.
    Post results and we'll see. If you're not far from UB4 i can help you out...
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  6. sonix
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    sonix New Member

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    [Dec 30, 2007]
    okido, I'll look for that today...

    When driving today, I noticed the car accelerating uphill in a 'sinusoidal' way, if you see what I mean. Looks like the waste gate opens and closes all the ime due to a lag maybe?

    I'll post the results whenever I have them.

    Cheers,
    #5
  7. sonix
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    sonix New Member

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    [Dec 30, 2007]
    Got me busy doing the test runs and logging with VAG, scared some people doing the full throttle stuff in 3d gear :ermm:.

    Here are the results;

    http://sonix.dommel.be/sonixlogs.zip

    fyi; I did the basic settings number 4 twice, as the first time with a cold engine, it started stuttering after some time...
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  8. etronic
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    etronic TDI VCDS Map User

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    [Dec 30, 2007]
    First question is who have done remap for you and how long you're driving your car with this mod??
    I do remaps myself and to be honest i wouldn't take boost so high in this car.
    There is a problem with begining of injection as well.
    To my opinion this soft have been written to kill your car. Best way to diagnose your car is to rewrite your stock soft and then log it once again.
    Most probably something went wrong already thats why car behave strange... Take it to you tuner and ask your money back as well as your original soft in ECU.
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  9. sonix
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    sonix New Member

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    [Dec 30, 2007]
    Have been driving with the remap for almost 2 years now, without any problems.

    The problems just began recently. I flushed the injection system with Xenum (have good results with this), and actually the problems started after that. But I don't really see what this could have to do with it.

    I'll try to get the ori file back on it and see what happens.

    Could you tell me what the problem exactly is with the injection timing?

    cheers
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  10. etronic
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    etronic TDI VCDS Map User

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    [Dec 30, 2007]
    It seems that timing is too early but it might be caused by soft. Getting a stock soft will ease diagnosis...

    BTW where do you live?
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  11. sonix
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    sonix New Member

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    [Dec 30, 2007]
    OK, if you want I can send you the remapped file as well to see if this timing and boost issue is caused by the remap itself.
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  12. etronic
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    etronic TDI VCDS Map User

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    [Dec 30, 2007]
    Have you done remap yourself or you bought it on ebay or somewhere else:). Send it and i'll see what it is.
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  13. sonix
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    sonix New Member

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    [Dec 30, 2007]
    Hehe, no, I'm a car mechanic myself, but don't have enough remapping knowledge myself. I bought the remap from secretauto.fr.

    Can you PM me your email adress, so I can send you the files?

    Cheers!
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  14. sonix
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    sonix New Member

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    [Jan 1, 2008]
    Happy newyear people! :)

    Question: How can I tell if my AWX engine has a variable nozzle turbo?
    I'm thinking of possible sticky vane control.
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  15. etronic
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    etronic TDI VCDS Map User

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    [Jan 3, 2008]
    Hey sonix!
    Of course you turbo is VNT. If you were driving dynamically shouldn't be any problem with this.

    Check your PM.

    Happy New Year to all of You guys!!!
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  16. sonix
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    sonix New Member

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    [Jan 14, 2008]
    Folks, problem solved!
    Appeared to be the nozzles of the VNT got stuck.
    Added quite some cleaner to the fuel, and drove at full throttle for 15 minutes.
    Everything runs now as it should! :)

    Anyone having some uneven acceleration, turbo not reacting smoothly, try this cheap and effective measure first.

    Cheers
    #15
  17. calechestudios
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    calechestudios New Member

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    [Mar 27, 2008]
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