Author Topic: AUDI AAN Extremely frustrated with VEMS: can't get ECU to communicate  (Read 15476 times)

Offline LKSi

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The other night, my friend who has a lot of experience helped me get started tuning my car on VEMS.  It ran ok on the base tune after we changed the injector scaling.  However, the car would have an erratic trigger error at about 2000 RPM.  I am assuming this is because I am using a 7A flywheel and something screwy is happening.  My friend recommended that I first try to update the firmware on the ECU to see if that helps with the trigger error.  Today I did as he suggested and everything went wrong.  The car would not start with the new firmware and even worse is that VEMStune can no longer detect the ECU at all.  I need to revert back to the old firmware and configuration, but I have no way of doing so.  I have tried EVERYTHING I can think of to get the VEMStune to detect the ECU and it just will not work.

I am seeing this when I open up VEMStune:


gifs upload

I have run out of ideas and frankly I am very upset with the situation.  I currently have an unusable ECU in my car.  Please help!

Offline VEMS

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Hello LKSI,

There is way to force the ecu in bootloader mode called serial loopback, i'll outline the procedure for you:

1) power down the controller (v3 ECU or round)
2) remove fuelpump, injector and ignition fuses (or relay), and remove injector connectors.
3) disconnect any device (usually PC) from the controller (GenBoard or round)
4) connect the ECU RS232 (serial port) DSUB9 pin2 to pin3, with a wire, a conducting paperclip, or a dedicated loopback connector
5) power up v3
6) remove the loopback
7) connect PC to v3 RS232 (serial port)
8 ) start VT, in preferences->communication settings press the detect button, it should detect the ecu
9) in the popup which says bootloader mode detected press the stay button
10) in tools firmware->firmware upload _do not use the wizard_ select your previous firmware and upload it to the ecu.
11) upload a know good config to the ecu (saved map from before upgrade gone bad).

After this your ecu should be behaving as before the firmware upgrade, if you run into any trouble please report.

Best regards, Dave



Offline LKSi

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I have tried the loopback many times with no success.  The ECU will not go into boot mode and it will not communicate with the PC.  The VEMS LCD screen is powering on so I know the ECU is getting power.

Offline VEMS

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Hello LKSi,

Is the LCD screen initialized, e.g. showing text or is it just 2 rows of black squares (or only backlit without squares) ?

Best regards, Dave

Offline LKSi

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It is showing blank squares

Offline Denmark

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I had the same with a brand new pcb ,
No communication , VEMS Denmark says its the atmega that destroyed

So i have to buy a new one  :(

working on the boxer

Offline VEMS

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I had the same with a brand new pcb ,
No communication , VEMS Denmark says its the atmega that destroyed

So i have to buy a new one  :(
Any new PCB / Ecu which does not communicate new out of the box will of course be replaced under warranty.

Best regards, Dave

Offline VEMS

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It is showing blank squares

That indicates either bootloader mode or no ecu startup at all, are you sure that you have re-enabled ecu communication after getting the dialog message which says "ecu communication is now disabled" ?

As an independent second test you could try the following:

1) download Bray terminal from: http://www.vems.hu/files/TuningSoftware/TerminalProgram/BrayTerm20030217.zip
2) open the program and select baudrate 19200, 8 databits, no parity, 1 stopbit, no handshaking and press connect.
3) in the bottom of the screen enter "S" (maybe a few times)
4) the ecu should respond with "AVREFI1" or alike.

If you get a response, than bootloader is running and serial connection is working (good), if you do not get a response either bootloader is not running or serial connection is bad.
To verify the serial connection we could test it in loopback mode, connect serial pins 2/3 on your dsub-9 male connector (coming from PC), in terminal program everything send in bottom screen should be returned in top screen.

Please get back to me with your (detailed) findings, we'll work from there.

Best regards, Dave




Offline PeepPaadam

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Re-enable the communitacion in VEMStune and I am pretty sure that VEMStune then detects ECU as being in bootloader mode.

The fact that VEMS is in bootloader mode shows that something was interrupted during firmware flash..

Offline LKSi

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No matter what I did, VEMStune would not communicate with the ECU.  I tried probably 500 separate times using 2 laptops and 2 different cables with no success.  The ECU has been sent to Marc Swanson to be looked at.  Thanks for the help.

Offline Denmark

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Look forward to hestehale the problem is / was when you get it back ,
Probbely the same fault as mine

working on the boxer

Offline LKSi

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Marc could not fix it so now it is with VEMS US in Vermont.  Which really sucks because they never answer the phone or respond to emails.  I hope I get it back.

Offline Denmark

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Re: AUDI AAN Extremely frustrated with VEMS: can't get ECU to communicate
« Reply #12 on: July 30, 2015, 05:39:41 pm »
Did You find the solution to this ?

It seems to be the same problem with a new PCB that i Got høre :(

working on the boxer

Offline VEMS

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Re: AUDI AAN Extremely frustrated with VEMS: can't get ECU to communicate
« Reply #13 on: July 30, 2015, 08:20:37 pm »
Hello Skassa,

Did You find the solution to this ?
It seems to be the same problem with a new PCB that i Got høre :(
Posting the same Q in multiple treads usually does not provide more answers, it does however fragment the discussion not helpful at all

Best regards, Dave