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VCDS logging suggestions on what to log.

Discussion in 'A3/S3 Forum (8L Chassis)' started by Westy, Feb 2, 2011.

  1. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Feb 8, 2011]
    Mate there's no key on your graph, what do the axis represent?
    #41
  2. S3KO4
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    S3KO4 Member

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    [Feb 8, 2011]
    scusa, the Y axis is number for for GS and Nm torque, and the X axis is time durations.
    #42
  3. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Feb 8, 2011]
    Ah ok, makes sense to me now. I used to get a MAF reading of 204 g/s which is about 255bhp and around 280lbft torque but now mine is pants.
    #43
  4. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Feb 8, 2011]
    Ok, tonight I went over all my boost hoses looking for splits or weaknesses and all seems fine. There was a spplit in one of the pipes coming off the charge pipe that had been cut into by the jubalee clip but I dont think that was causing any problems.

    Took the car for a spin and its still not right! It just doesn't feel like its pulling as hard as it used to. I got a peak MAF reading of 192g/s which is about 240bhp. I'm starting to get the feeling that the timing maybe getting pulled quite a bit but when I tried to log block 020 all the fields stayed at 0! After a bit more investigation it appears that the VCDS label file for the engine module (8N0 906 018 BH) is missing. I re-installed VCDS and still no file, WTF!

    Anyway I decided to log some Lambda data and thought I'd post it up to see if anyone can make any sense of it for me:

    Block 034:

    Lambda factor went from 1 to 1.016 to 1.023, 1.031, 1.039

    Block 036:

    Voltage was all over the place 0.1, 0.095, 0.09, 0.011, 0.105, 0.09, 0.095

    Block 037, which i believe shows the life of the sensor showed a "difference" of 0.004

    does any of this mean anything to anyone and is it ok? The hunt for the fault continues.
    #44
  5. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Feb 9, 2011]
    Right can anyone confirm this for me? I think i might have answered my own question above.

    On the TT logging guide I posted the other day it mentions the following for block 037 - Lambda System Diagnosis:

    "The Value in field 2 is the post-cat lambda probe output voltage, with a range of 0.10 - 0.95V. It should remain as constant as possible. Considerable voltage fluctuations are an indication of catalytic convertor damage."

    Jusy to give you an idea of my voltage:

    0.125
    0.11
    0.09
    0.08
    0.08
    0.15
    0.68
    0.4
    0.07
    0.08
    0.745
    0.64
    0.735
    0.63
    0.095
    0.18
    0.4
    0.095
    0.71
    0.71
    0.735

    "The third field is lambda correction value between the pre and post-cat sensors. It should stay below 0.02"

    I have a constant reading of 0.04

    Can anyone confirm if this means I have a shagged cat/sensor as VCDS isn't throwing any relating erros?
    Last edited: Feb 9, 2011
    #45
  6. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Feb 9, 2011]
    Just gone back over my log from last night on block 020 for the injector timings. Originally I thought that the timing wasn't being pulled but I've just noticed a slight pull of 3 on cylinder 1 at 6500 revs but that was it. I fail to believe that this is correct as I remember pulling 5s and 6s last year when at the red line. Any suggestions?
    #46
  7. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Feb 9, 2011]
    Anyone got any ideas or am I just confusing you all???

    I did the boost leak tests as described in the sticky at the top of the board and I got the following readings:

    3000 revs and the MAF was just ver slightly below 10 g/s
    on the Lambda fuel trim test, block 032 I had readings of 1.3% and long term of -0.8%. After I reset them the short term gradually rose from 0 to 1.3% and long term stayed at 0% so i'm assuming no leaks anywhere.
    #47
  8. S3 TAM
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    S3 TAM Pocket now empty

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    [Feb 9, 2011]
    Calling Bill....
    #48
  9. S3KO4
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    S3KO4 Member

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    [Feb 9, 2011]
    Too advanced for me, Badger, Tuffy, and Welly are your men on these sort of figures.
    #49
  10. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Feb 9, 2011]
    I might have to drop them a link to this thread via a PM. I've learnt a lot about VCDS logging this week but my car still isn't right!
    #50
  11. S3 TAM
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    S3 TAM Pocket now empty

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    [Feb 9, 2011]
    2nd that, was out last night with westle loggin with vag com, deffo power loss somewhere but everything we checked seems to be ok. This ones got me scratching my head.

    Dont worry matey we'll get to the bottom of it.
    #51
  12. S3KO4
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    S3KO4 Member

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    [Feb 9, 2011]
    I have leaned a bit myslef. cheers
    #52
  13. Welly
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    Welly VX220 SC Driver :)

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    [Feb 9, 2011]
    OK, first off, what engine is it? Engine code I mean as this can effect what could be wrong. The early ones are a lot more simple... Lol.
    #53
  14. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Feb 10, 2011]
    It's a BAM engine running a stage 1 map with autobahn TIP, no other mods.

    I have been thinking weak actuator. The car has done 122k miles with no indication of the turbo being changed.

    Cheers for looking mate.
    #54
  15. S3 TAM
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    S3 TAM Pocket now empty

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    [Feb 10, 2011]
    Badger have you got any ideas.

    maybe a little pointer..

    Cheers
    #55
  16. Welly
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    Welly VX220 SC Driver :)

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    [Feb 10, 2011]
    Sorry for the delay, have been busy this week.

    Westle, you may be onto something. You post cat lambda readings are very irratic. You are potentailly looking at a knackered cat - and a knackered cat normally means a blocked/restricted cat also. This certainly will not help with flow through the engine, and could well lead to the lower G/S readings you have been seeing.

    I would consider getting underneath and tapping the cats gently with a hammer to listen for any rattling - don't go too mad though. Failing that, you could also get one of the THS decat pipes that fits in place of the OEM cats. This would at least be a suitable test - however won't be the cheapest test it the world as you have to buy the part.

    I can't remember and now I have started typing, but have you checked out everything that could be causing a leak from the charge pipework. This is the other likely cause if all the vac hoses around the engine bay are sound. You would normally expect to see a fault code for pressure loss - however I would chack none the less.

    I wouldn't tweak the actuator - you need to check out block 115 to see if the turbo is making requested boost before tweaking the actuator - if it IS making requested boost, then the actuator is OK.
    #56
  17. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Feb 10, 2011]
    Many thanks for looking Welly.

    I have posted a boost graph a bit higher in this thread and the boost is reaching requested but is dieing off quite quickly after. I have checked all boost hoses and did check the ones coming from the charge pipe, all look ok.

    Can you explain what looks suspect on the post lambda sensor. Also is it worth me doing a more detailed log of this sensor?

    I have an MOT tomorrow so if the cat is shagged is it likely to cause emissions problems that will fail the test? If not, I'll order myself a decat pipe and get a sports cat sorted for next years test ;)
    #57
  18. Welly
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    Welly VX220 SC Driver :)

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    [Feb 10, 2011]
    The voltage is all over the shop on the log you posted of post cat lambda, however, i guess you were driving at the time, so that's not exactly specific. The idea with that probe is that the voltage should be reasonably constant, but it's flitting about all over the shop.

    I grant you you would normally expect a fault code if the post cat sensor reads too high, but there is the possibility that it may have been mapped out.

    It's certainly something to check if nothing else.

    If there is nothing else, and it turns out that the cat is fine, and there are no leaks, then it's getting hard to tell at that point without seeing the car. There are so many things that can have an impact. For example, and this is only an example, if the MAP sensor is overreading charge pressure, then you may be getting less boost than it says, which will affect mass flow and performance.
    #58
  19. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Feb 10, 2011]
    That voltage reading was whilst idle mate!

    I've now got my eye on a THS de cat on ebay ;)
    #59
  20. Welly
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    Welly VX220 SC Driver :)

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    [Feb 10, 2011]
    That was at idle? Bugger a goldfish...

    I would first off unplug (electrically that is) the second lambda and go for a logging session. OK, you will have a fault code, and I am not sure how losing the post cat lambda will affect the later wide band ECUs, but may be an easy way to eliminate a faulty sensor without spending any money...

    Don't go buying a decat just yet, it might just be a duff sensor. And a sensor is cheaper than a replacement cat/decat.
    #60
  21. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Feb 10, 2011]
    Any idea where the sensor is located to unplug?

    If I dont use the de cat I can re list it at the same price so it's no biggy.
    #61
  22. Welly
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    Welly VX220 SC Driver :)

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    [Feb 10, 2011]
    True...

    The sensor plug (I think as my car doesn't have one... :)) can be found on the drivers side on the belly (i.e. to the right of the exhaust) about level with the cats, in a white plastic bubble protector thing, which you have tto take off to access it.
    #62
  23. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Feb 10, 2011]
    Ok Welly cheers.

    I'm heading out now to see my friendly mechanic and get it up on the ramps. I'll let you know how it goes.
    #63
  24. Welly
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    Welly VX220 SC Driver :)

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    [Feb 10, 2011]
    You don't need ramps for that dude I promise, easy as pie and very doable on a trolley jack and an axle stand.
    #64
  25. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Feb 10, 2011]
    Well friendly mech didn't have room in his garage for me to check tonight but he's suggested to try changing the post cat sensor as he would have expected an error light or code if the cat was on its last legs!
    #65
  26. finesse
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    finesse Active Member VCDS Map User

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    [Feb 10, 2011]
    expensive part to change in trial & error

    test the lambda


    2.8.3 Block 030 – Lambda Control Operating Status
    Note! Before continuing:
    • Adjust the engine RPM to 2000 using the handy tool, or your steady leg
    Enter the Basic Settings block 030.
    In block 030, the fields 1 and 2 are three-digit binary codes that give the status of
    the oxygen sensors. The first digit indicates the probe heating status, the second
    digit indicates the probe condition, and the third digit indicates lambda control
    status. The value should fluctuate between 111 (heater on) and 011 (heater off).
    The last two digits can also fluctuate between 1 and 0, but should be
    predominantly 11.
    Do not continue with testing until the displays have reached 111 in field 1 and
    110 in field 2, at least once.
    2.8.4 Block 034 - Ageing of Pre-Cat Oxygen Sensor
    Enter the Basic Settings block 034.
    Field 2 shows the Exhaus Gas Temperature, measured by the oxygen sensor. It
    must be above 350°C for the test to succeed.
    The value in field 3 is called “dynamic factor”. It is an indicator for lambda probe
    ageing. The value should be above 0.5; the value for a new sensor is ~2.0. It will
    decrease as the sensor ages.
    The field 4 will say either 'TEST OFF/ON' before/while the test is running, and
    either 'B1-S1 OK' or 'B1-S1 NOT OK' afterwards. It may take several minutes to
    obtain result of diagnosis.
    Do not continue with testing unless the field 4 is indicating “B1-S1 OK”.
    2.8.5 Block 036 - Post-Cat Oxygen Sensor Diagnosis
    Enter the Basic Settings block 036.
    The field 2 will say either 'TEST OFF/ON' before/while the test is running, and
    either 'B1-S2 OK' or 'B1-S2 NOT OK' afterwards. It may take several minutes to
    obtain result of diagnosis.

    Do not continue with testing unless the field 2 is indicating “B1-S2 OK”.
    2.8.6 Block 037 – Lambda System Diagnosis
    Enter the Basic Settings block 037.
    The value in field 2 is the post-cat lambda probe output voltage, with range of
    0.10 … 0.95V. It should remain as constant as possible. Considerable voltage
    fluctuations are an indication of catalytic converter damage. A constant voltage of
    0.450V is an indication of damaged wiring.
    24

    The third field is lambda correction value between the pre and post-cat sensors.
    It should stay below 0.02.
    Note. If the lambda probe voltage is OK and the lambda correction value is still
    greater than 0.02, even after a test drive, this is an indication of ageing of the
    lambda probe upstream of the catalytic converter.

    The field 4 will say either 'TEST OFF/ON' before/while the test is running, and
    either 'System OK' or 'System NOT OK' afterwards. It may take several minutes
    to obtain result of diagnosis.
    Do not continue with testing unless the field 4 is indicating “System OK”.
    2.8.7 Block 043 – Ageing of Post-Cat Oxygen Sensor
    Enter the Basic Settings block 043.

    The field 4 will say either 'TEST OFF/ON' before/while the test is running, and
    either 'B1-S2 OK' or 'B1-S2 NOT OK' afterwards. It may take several minutes to
    obtain result of diagnosis.

    Do not continue with testing unless the field 4 is indicating “B1-S2 OK”.
    #66
  27. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Feb 11, 2011]
    Cheers finese but I have logged quite a few of the above mentioned blocks and fields and failed massively on the voltage fluctuation of the post cat lambda sensor.

    I will try to log a few more things this weekend if I fet the chance but at the moment the only thing failing it's test is that sensor.
    #67
  28. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Feb 11, 2011]
    Ok I've just re read Finese's post and I have the following results:

    Block 034 (pre cat lambda sensor)

    The self test ran fine once the temps were above 350 degrees but there is no field that reads "B1-S1 OK" as suggested above.
    The Lambda factor is 1.016 so the sensor is ok age wise.

    Block 036 (post cat lambda sensor)

    Voltage is all over the place for example:

    0.1
    0.095
    0.09
    0.11
    0.105
    0.09
    0.095
    0.135
    0.74
    0.68
    0.11
    0.05

    BS1-S2 OK

    Block 037 (Lambda system diag)

    Again voltage is bad:

    0.095
    0.1
    0.11
    0.125
    0.11
    0.09
    0.08
    0.08
    0.15
    0.68
    0.4

    The "difference" which is meant to stay below 0.02 is reading 0.004. It also ran its test ok but there is not a field to show "ststem ok".

    According to the above details if the voltage on the post cat sensor is bad it normally points at a damaged cat.

    My car is having an MOT as I type so i'll see if they pick anything up from that.
    #68
  29. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Feb 11, 2011]
    Just heard from the MOT centre and my car failed on the near side headlight beam being too low, which they are fixing now. When I asked if there was any indication that the Cats might be nackered or on their way out he said "nope, it's running sweet"!

    I'm stumped now, completely.

    I'm going to try unplugging the post cat sensor as Welly mentioned above and I'm also going to get a compression test done just for the hell of it.
    #69
  30. finesse
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    finesse Active Member VCDS Map User

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  31. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Feb 11, 2011]
    Cheers for than mate, I'll take a look at the sensor on sunday.
    #71
  32. S3 TAM
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    S3 TAM Pocket now empty

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    [Feb 11, 2011]
    I would of thought that connector is for the sensor on the DP not post Cat.
    #72
  33. badger5
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    badger5 www.badger5.co.uk Site Sponsor

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    [Feb 11, 2011]
    excellent info.. learnt summat also there.
    cheers
    #73
  34. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Feb 19, 2011]
    Right I now have a brand spanking MAF and N75 (they needed doing anyway) and some new silicone hoses but I'm still down on power. I still need to investigate the lambda sensor when i get a chance. Does anyone know if its easy enough to swap this sensor with another car for testing purposes?

    I also need to do some more logging on my timing pull as that didn't seem right at all!
    #74
  35. S3 TAM
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    S3 TAM Pocket now empty

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    [Feb 20, 2011]
    bump...

    We can try my Lambda on your car i think it needs some type of sealant??

    anyone
    #75
  36. Welly
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    Welly VX220 SC Driver :)

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    [Feb 20, 2011]
    Sealant? No sealant needed for lambda sensors. Just bolt it up tight. May also need some heat to get it out.
    #76
  37. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Feb 20, 2011]
    I've got a gigantic boost leak somewhere at the moment! Since removing the charge pipe read hose and replacing the small charge pipe hoses I now have air rushing around all over the place!

    I'll get that sorted and then we'll tackle the lambda abnormalities.
    #77
  38. finesse
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    finesse Active Member VCDS Map User

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    [Feb 20, 2011]
    Bloody S3's and their issues. :):)
    #78
  39. Essflee
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    Essflee Well-Known Member

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    [Feb 20, 2011]
    I'd agree with that lately...:banghead:
    #79
  40. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Feb 20, 2011]
    Yep I just want to get the thing running right so I can spend some cash on upgrades!
    #80

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