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A4 B7 After remapping problems...

Discussion in 'Audi S4/A4/A4 Cab (B7 Chassis)' started by iucle, Jun 24, 2014.

  1. iucle
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    iucle Member

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    [Jun 24, 2014]
    Hi guys!
    I just want to share my experience about remapping and ask you some advice. I have an A4 B7, 1.9 Tdi and I recently installed one of the remapping boxes that give you 30hp more (From 115hp to 144ho).
    The plus side of the remapping is that it gives me more mpg (60-63mpg on motorway compared to 50-53 before). The lag of the pedal gone and it's really responsive now, a great drive. But....
    Started having problems shortly afterwards. I never had engine or drive problems before (had the car for 3 years and done 35k (it has 163k on the clock).

    1.) First one was more noise from the engine. After inspecting I realised that the engine cover looked to be loose (two of the rubber things between the cover and the engine were consumed and the plastic vibration Was the problem. I wasn't able to find those online so don't know if it's possible
    change them.

    2 .) Noise while turning wheel to both sides: after some research, it looked to be a cv boot. Inspected both and looked to be perfectly clean and tidy. Anyways took both half shafts off and after inspection turned out that both inner cv were gone.
    Replaced both, installed and the noise While turning disappeared.
    I suppose that given the higher torque after remapping the inner cv's just got worn faster.

    3.) Now after driving about half a tank it feels like on acceleration there is a micro vibration on the gas pedal. I've noticed that between 1.5 and 2.5 thousands rpm I can feel the vibration. Then it disappears after 3000rpm and doesn't get back when decelerating.
    After some research it looks like the flywheel. This could be an expensive one if it turns out that it's the flywheel..

    Could someone advise me on the last one?
    I want to anticipate that when changing the half shaft inner cv, upper or lower arms were not removed so it can't be an alignment or balancing problem ( I used all torque specification from Audi when reinstalling.

    Nothing else comes into my mind beside the flywheel. The vibration is not major, but really only I can feel it as I know that it wasn't there before.

    Thanks.
    #1
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  3. Rick @ Unicorn Motor Dev.
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    Rick @ Unicorn Motor Dev. Site Sponsor Site Sponsor

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    [Jun 24, 2014]
    If you are going off the display our mpg increase is wrong. The biz fools the ECU into thinking it is using less fuel than it actually is. It's also probably giving you too much torque very low down so the transmission is under too much stress

    Rick
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  4. iucle
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    iucle Member

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    [Jun 24, 2014]
    So do you think it can be the flywheel?
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  5. Rick @ Unicorn Motor Dev.
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    Rick @ Unicorn Motor Dev. Site Sponsor Site Sponsor

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    [Jun 26, 2014]
    Yes I would think so.
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  6. Gazwould
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    Gazwould Active Member

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    [Jun 26, 2014]
    Put the box in the bin .
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    DieselJake likes this.
  7. desertstorm
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    desertstorm Well-Known Member

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    [Jun 26, 2014]
    I think you are getting confused between a remap and a tuning box. There is a world of difference. A lot of tuning boxes for the 1.9 TDI are simply a resistor and some of them are well expensive over £100.
    At 163K the DMF and clutch will have seen better days. By increasing the low down torque you may have pushed a borderline failing clutch / DMF over the edge. I would try taking the tuning box off and see how it runs without it, worn CV joints are common if the gators have split and the joint gets water/ grit in it. The CV boots seem to crack very easily.
    If you can put a picture / link up of the tuning box that would help. Where does it connect to on the engine ??

    Karl.
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  8. iucle
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    iucle Member

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    [Jun 26, 2014]

    Hi Karl, thanks for your reply.
    I am attaching the tdi box that I have installed. Paid £124 for it.
    tdi box.jpg

    Here is the link to the website as well: TDI Tuning - Diesel Tuning Boxes - Diesel Tuning Box - Browse Products[]=0000000316/category_drop_down_1=0000000007/category_drop_down_2=0000000008/category_drop_down_3=0000000079/category_drop_down_4=0000000316/

    It connects to the engine sensor of which I don't know the specific name. Here you have a specific picture:
    passat 1.9 tdi.jpg

    For the cv joints, they were actually perfect when I took them out. Inner and outer had no gators worn or split whatsoever. That was my initial concern as I wasn't able to understand why there was a clicking noise when turning. I looked a lot on the web in order to be able to diagnose the failed inner joint. After changed I have no clicking now.

    I will try to remove the the tuning box today and will let you know how it runs without it.
    #7
  9. desertstorm
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    desertstorm Well-Known Member

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    [Jun 26, 2014]
    Sorry to say that is one of the resistor mod tuning boxes. It is connected to the fuel temperature sender and you can get exactly the same result with a 2p resistor from Maplin.
    They make it look complicated with a box and a multiway connector but in reality the engine sensor is just a thermistor whos resistance alters depending on the temperature of the diesel coming from the engine.
    If the diesel is hotter there is less mass so to get the same amount of power you need to inject for a longer duration.
    I played with this on my Passat several years ago, use a 150 ohm resistor and you get this

    [​IMG]

    The engine thinks fuel temp is nearly 130 degrees C however in reality it's probably only 65 degrees C. Thus more diesel is injected so you get more power /torque. However this happens all the time so it's like running a petrol car on choke even when it's hot.
    This can lead to excessive smoke leading to the VNT mechanism getting fouled on the car.
    Because the car is actually injecting more diesel than the ECU knows about the mpg appears to increase, but if you actually measure the fuel consumption brim to brim you will find no improvement.
    Also the effect of the fuel temperature correction is less marked at higher RPM so I believe above something like 3000 RPM there is very little extra fuel injected. So the car feels more lively at lower - mid RPM and appears to give better fuel economy.
    If I was you I would remove the box and try and get your money back.

    Karl.
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  10. desertstorm
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    desertstorm Well-Known Member

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    [Jun 26, 2014]
    Heres what my tuning box looked like.I left it on for a day just to gauge what it would do, I was getting 70mpg on a journey where I would normally get 45 mpg.

    [​IMG]

    You could make an adjustable version with a 150 ohm resistor in series with a 100 ohm potentiometer
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  11. iucle
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    iucle Member

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    [Jun 26, 2014]
    Hi Karl, this is impressive!
    I would have never thought its so easy. Plus it looks I was robbed....
    On top of that I got all the failings....

    Do you think the flywheel is going bad because of the amount of torque I get?
    What would you recommend beside removing the Tdi box and reclaiming my money back?
    The car looks lively but of the problems will continue coming...turbo..injectors?...
    #10
  12. desertstorm
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    desertstorm Well-Known Member

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    [Jun 26, 2014]
    I have to add the 70mpg was indicated by the car, it wasn't actually doing that this mod knocks the calibration of the trip computer out by miles.

    Karl.
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  13. TDI-Tuning
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    TDI-Tuning Site Sponsor Site Sponsor

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    [Jun 27, 2014]
    Hi iucle,

    We've just seen the above posts relating to your vehicle. As you have not made contact with us, would you kindly call us so that we can discuss this matter with you to try to help you.

    Please be advised, there is no reason why our product would have caused these issues to your vehicle, as the PD box only connects to the vehicle's fuel injection system and every aspect of the engine is governed by the ECU which is always in control of the engine. However, we will be happy to help you in anyway that we can.

    Just to clarify, our PD tuning box doesn't simply send out a static signal like the example given above. The signal is constantly changing based upon the input from the vehicle. This ensures that the PD box doesn't cause over-fuelling which is associated with a static signal produced by a resistor.

    Customer service is imperative to us and we will be more than happy to answer any questions you have or discuss this further on 01245 924 400.

    Kind regards,

    The TDI-Tuning Team

    Diesel Tuning | Diesel Engine Tuning | TDI Tuning
    #12
  14. desertstorm
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    desertstorm Well-Known Member

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    [Jun 27, 2014]
    So I take it you are using the original sensor resistance in parallel with a low value resistor to provide some kind of small variable effect based on the actual fuel temperature. Still quite a lot of money for not a lot of technology, and putting the components into a nice aluminium box with a multi way connector makes it look like a proper tuning box.
    The cheap boxes on Ebay are just a simple resistor

    Resistor in a box

    Tuning Box

    http://www.audi-sport.net/vb/diesel-tuning-uk/179651-why-diesel-tuning-boxes-have-bad-name.html

    Frequently asked questions that Beyond Performance 4x4 regularly answer

    If you have VAG-COM you can use it to see what the fuel temperature is doing without doing anything to the box.
    #13

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