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3.0TDI CCWA - trying to understand EGTs

Tjaart Feb 19, 2018

  1. Tjaart

    Tjaart New Member

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    I am seeking some insight towards understanding my car's health status. First off, the car:
    2010 Audi A5 Coupe 3.0 TDI. CCWA and S-tronic. (135 000km on the clock)
    BMC air filter, 76mm Downpipe (rear boxes cleaned out), 550x230x65 Intercooler, ECU software and oil-to-air oil cooler. VCDS scan shows no error codes for ECU or TCU.

    My gut tells me that my "Governing factor exhaust temp" is interfering maybe more often that it should. Suggesting that something is maybe acting out or I am asking too much from the car in its current state (supporting mods not supporting enough).

    I do track events with the car, and some tracks have straights long enough to to see 3rd to 5th gear pulls. Ambient here in South Africa is 26-35 degrees Celsius for most events during the year. Before these brutal events happen later in the year, I would like to try and find out if the car's health is off before I break something.

    The ECU software:
    EGR and DPF disabled.
    Boost peaks at 1.78bar and drops to 1.43bar up top
    Peak "Mean injection quantity" is around 72 mg/stroke
    At a recent Dyno event, the car made 199.6kW and 602Nm (all wheel figures)
    I did ask not to push the car too hard as I do lean on the car hard during track events. So reliability first.

    On a 34 degree C day, a 5th gear pull will raise the intake temp to 61 degrees. Colder days it will peak to 53, but it gets there pretty fast (4-8 sec from WOT).

    The latest log I ran today: (26 degree C ambient)
    Road is relatively flat
    5th gear, IAT = 34.6, EGT 515. Apply WOT and in 3seconds: IAT = 38.1 and EGT 846
    Some of the torque limitation even happens around 3800rpm.
    Max EGT I saw from all the logging was 891.
    I also ran a partial throttle (70%) in 5th, from IAT=36 & EGT= 548, 2.2 sec later: IAT = 38.7 and EGT 854

    I did a 1/4 mile event Yesterday. Only managed 14.3 at 152km/h (94mph). The TCU is stock so it's launch is average. I could feel the car limiting torque in 4th.

    To me it seems as if the EGTs go up faster than it should and I am experiencing more torque limitation as a result. With my limited knowledge, I don't think the software is doing something silly. Mean injection is not extreme and there is good boost to support a clean burn. Air intake temps don't seem to be super high even though the ambient is hot. So not sure the supporting mods are causing this regular limitations.

    I am wondering if unhealthy injectors can cause this. Perhaps some un-burnt fuel is burning in the manifold.
    VCDS injection deviation at idle is less than 0.5 and more than -0.4. But I can see a slight white haze from the exhaust after idling for a while and during driving the deviation on some injectors go to 2.7.
    I am going to send an oil sample in for lab testing, but I don't see any rise in oil level.

    Any input will be appreciated. Either I am over thinking this or something is being a party pooper.
     
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  3. desertstorm

    desertstorm Moderator Staff Member Moderator VCDS Map User Audi A4 Audi Avant Owner Group quattro TDi

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    Are you still running with the DPF ? Have you tried logging the DPF pressure sensor to check the status of the DPF. It doesn't sound as if you are pushing the car too much. What fuel pressure are you running. More fuel pressure will lead to shorter injection events.
    The factory EGT limiter cuts in at 850 degrees as this is what Garret say the turbo can do on a continuous basis . I have been running my car at 900 degrees now for a few years and haven't had any issues on a hybrid it's making 380bhp and 750Nm .
    It's quite violent when the fuel cut happens as the EGT hits the limiter.
    Bobby @bobby singh will know a lot more about the CCWA, He spent a lot of time tuning his and has done many other peoples cars.
     
  4. Tjaart

    Tjaart New Member

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    DPF is out. I replaced the DPF with a 76mm downpipe.
    I have also disconnected the exhaust in the middle of the car. So back pressure should be minimal.

    I have not logged the Fuel pressure as yet. I will do that today. Interesting insight. I did not know what impact the Fuel pressure will have on the temps.

    My EGT limiter is still at 850 degrees. I am fearful to bump that up to 900 degrees for the reason that with the time trail events some hot laps take 2 minutes and 40 sec. If what I am experiencing is normal and the turbo can run 900 degrees all day, it is something I can consider. I first want to make sure the car is healthy before lifting safety parameters.
     
  5. bobby singh

    bobby singh BSR VCDS Map User Audi A4 quattro TDi

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    900 is ok - some even remove limiter and call this race tune lol or even screw the calibration so egt is shown less but in reality has more...
    What you are experiencing EGT factor correction.
    This is when the ECU feels the EGT is going up to quickly based on the model and reduces fuel - this can happen when the egt is below the limit.
    It pretty complex and requires some time to tune correctly.

    Again this is the difference between correct calibration against generic tune or even custom - custom doesn't mean correct :)
     
    Last edited: Feb 20, 2018
  6. Tjaart

    Tjaart New Member

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    Thanks for the input. By no means do I want to fool the ECU to think it is seeing lower EGTs. The EGT factor correction is doing a good job. I just need to get the car not to rely on the EGT factor correction so often. If I read between the lines, it seems software tweaks are needed more than the injectors or something else being unhealthy?
    I also did not find any info on 3.0TDIs with high EGTs due to leaking injectors.

    I had time to think about the 1/4 mile times I did. I think a big contributor to me not running sub 14 sec is perhaps the stock TCU being gentle even with launch control. Wheels don't spin off the line. But gentle = reliable. So catch 22.


    On a side note: @desertstorm and @bobby singh, Spectacular monsters you guys have. Some fast 3.0TDI out there, but not a lot of people share so much details.
     
  7. Tjaart

    Tjaart New Member

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    A lot more thinking and doing happened.

    Speaking to some fellow 3.0tdi guys here, a 14 sec quarter seems more normal for our altitude (1750m) and fuel supply with a stage 1 file.
    I do however agree with @bobby singh in that the software can be better to keep the torque limiting factor happier. So I with visit that idea a bit later.

    I have since installed new injectors.
    Original parts were 0445116023. Bosch supplied 0445116022 as the replacement units.

    The car is definitely better across the board. The Torque limiting factor is less intrusive in the higher gears. Meaning I cannot feel any power reduction in 3rd and 4th. 5th gear I still get in the higher RPM, but I deem that more normal. I have not driven the car long enough to confirm completely. Time will tel.

    Whilst installing the new injectors I came across 2 things that raised some questions:
    1) Injector 4 had massive build up. If I were to guess, this injector might have leaked quite a bit causing more gunk(for the lack of a better word) and the copper washer started to pass some of the gunk into the injector passage. any thoughts?
    [​IMG]
    2) Whilst busy in the engine bay I removed the metering valve on the CP4 pump for inspection. I found 4 metal shavings. From researching the bleed procedure after fitting the injectors, the engine cannot be attempted to start without the HPFP being filled up with fuel (3 min on the aux pump). Otherwise instant damage. Can these flakes be from previous mechanics not adhering to this resulting in these flakes over the history of the pump. Or is the pump starting to eat itself?
    I will keep an eye on this and do some spot checks every now and then. It is a 30-45min job.
    [​IMG]
    [​IMG]
    [​IMG]
     

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  8. bobby singh

    bobby singh BSR VCDS Map User Audi A4 quattro TDi

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    Metal in the pump is early sign its about to go - often when the pump fails the injectors are ruined too as metal goes into them and impossible to remove (its not a diy job).
    That injector appears to be leaking for sometime - when a injector seal leaks like this often the nozzle is screwed and sprays excessive fuel causing rail pressure low dtc.
    Time for a CP3
     
  9. Tjaart

    Tjaart New Member

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    I feared this might be the case. After the cost of injectors this sucks quite a bit. Thanks for the input Bobby.

    I did not have any dtc errors for low rail pressure. Might have caused the CP4 to work harder now that I think about it, but at 72mg/stroke it is not like it was at max looking at what you got out of your CP4. Any how, I will look into a CP3 ASAP.
     
  10. bobby singh

    bobby singh BSR VCDS Map User Audi A4 quattro TDi

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    Confirm with your tuner he can do cp3 calibration otherwise you'll be stuck.

    Cheers
     
  11. bobby singh

    bobby singh BSR VCDS Map User Audi A4 quattro TDi

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    Btw the CP4 dies even with stock power - they are cr@p pumps to be honest.
    I took one apart and they are cheaply made and the cam wears pretty easy.
     
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  13. Tjaart

    Tjaart New Member

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    Agreed. I will consult him first. and ask around if he cannot.

    I believe the term used to best describe the CP4 pump is a "ticking time bomb", not if but when.
    Reviewing your thread your mentioned the belt on the CP3 was not tight enough and had to find the correct gear. Do you mind elaborating? If I were to fit the CP3 pump do I need to look for a specific gear to get the correct tension?
     
  14. bobby singh

    bobby singh BSR VCDS Map User Audi A4 quattro TDi

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    If you need a cp3 kit - drop me a pm I keep them in stock
     
  15. Tjaart

    Tjaart New Member

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    An update.

    After fitting the injectors the car felt better. Monday driving on the highway I got this bad boy:
    So EGT still a problem. The fuel rail pressure is not dropping and it is meeting requested values. Today I when back in my archive of VCDS logs to gain some perspective. The first event I did ever in stock form back in 2016 generated my first ever EGT error. Along with this naughty error:
    (Some can go "ah ha" right about now...)
    I cleared all the errors and it never showed it self again, so I never thought anything of it since. Today I googled a bit and found a Touareg forum discussing this error. His error was permanent, but in his description he described the symptoms before the actual failure as "occasional hesitation on acceleration (a "hiccup")". Boom.

    So long story short, I swapped the Temp sensor for Before the turbo with the After the DPF one. They both have the same black connector. So I connected them to their new locations and went VCDS logging.

    Max EGT I saw was 868 degrees.... in 6th gear. All the other gears regulated nicely below 850 degrees.
    [​IMG]

    I have struggled with this issue for so long. I am so happy that the car is pulling strong (for a stage 1 of course). I will do further testing over the next week to confirm this issue is resolved.

    Next steps are to sort out the unhappy HPFP.
     

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