No start! 2volts on fuse 31 and 33?

[AudiS2700Hp]

I think its best now to see if i can arrange a scoop to see how the can-bus signal looks?

But I'm not really sure the can-bus is the problem. If I'm right the immobilizer has a W wire to the ecu and the can-bus has two twisted wires to the other can high controllers. But would a missing can signal actually create the engine not to start? Weird thing is when I'm in the measure blocks on the trans i can still see the engine start RPM. I would think that's impossible when they can't communicate.


I also understand now the fault codes have nothing to do with the immo its just a problem in the communication of the can-high controllers.

[sweegie]

I wouldn't worry too much about CAN errors where other ECU's can't see the engine ECU - this can & will occur when you flash the engine ECU. If you clear them, they shouldn't come back though.

[AudiS2700Hp]

Mmmm okay. When i clear all the codes the fault in de instrument cluster comes back after a few starts but not in the ESP and trans yet.

To cheer me up i bought myself a oscilloscope. Hope to receive it next week so i can do some tests on the can-bus and other sensors.

But is there any way i can find out if the problem is related to the removal of the rear lambdas? I think its a little to much coincidence it happened just after that right?

[Shoppinit]

After the physical removal or the coding out? Have you got the possibility of flashing the original map back to test?

[AudiS2700Hp]

No just coding out. And I'm not able to flash the ecu my self. I asked the guy how coded it out for my and he says it has nothing to do with the car not starting. But I'm not sure. It gets a starting rpm but the injectors are not firing and i get no fault codes in the ECU.

[AudiS2700Hp]

I didn't think much about it but maybe its a important detail. When received the ecu i mounted it in the car and it started end drove fine. Then i shut it off and after one hour it would not start. So it head cycled just one time after the work on the ecu!

Is it possible the ECU found a problem in the software when i did use it for the first time and disables the the car to start again?

[Mɐʇʇ]

Do you get spark?
Does the fuel pump run when you first turn the ignition on?
When you crank it, do you see RPM output on VCDS?
What's the exact part no. of your ECU?

Who did the ECU flash? FWIW, you are able to flash it yourself, I've done it to DIY code out my SAI. And sweegie is a guru. - although coding things in and out is a bit more tricky than just reflashing.

My money:
a) is on a loose earth connection (or similar) somewhere. Maybe a broken wire
b) Toast ECU.

This is generic stuff, not specific to the RS6 motor (so I've not checked it's "exactly" this). To attempt to run the engine (successful or not), it generally needs as a minimum:
* crank signal
* throttle signal
* pressure or airflow signal (reckon it'll still have a go without this, though)
* fuel pressure
* coils firing
* injectors firing

When you turn the ignition on (or crank it) - does the fuel pump relay fire?

It's easy to check if plugs are firing.
Injectors are usually live from the injector relay and earth out through the ECU. So with power on, check for +12V on the injectors.

Most of the other sensors etc - it'll try and run, just maybe not very well.

[AudiS2700Hp]

Do you get spark?
Does the fuel pump run when you first turn the ignition on?
When you crank it, do you see RPM output on VCDS?
What's the exact part no. of your ECU?

Yes fuel pump runs when I turn on the ignition and I have rpm I'm vcds when I try to start the car yes.
Part number of the ecu is 4D1 907 558

Who did the ECU flash? FWIW, you are able to flash it yourself, I've done it to DIY code out my SAI. And sweegie is a guru. - although coding things in and out is a bit more tricky than just reflashing.

Some guy how' does a lot on vag ecu's. I wasn't brave enough to do it my self. But maybe now is the time to do it. But I just asked the guy how did my ecu if he wants to look at it again.

My money:
a) is on a loose earth connection (or similar) somewhere. Maybe a broken wire
b) Toast ECU.

This is generic stuff, not specific to the RS6 motor (so I've not checked it's "exactly" this). To attempt to run the engine (successful or not), it generally needs as a minimum:
* crank signal
* throttle signal
* pressure or airflow signal (reckon it'll still have a go without this, though)
* fuel pressure
* coils firing
* injectors firing

When you turn the ignition on (or crank it) - does the fuel pump relay fire?

It's easy to check if plugs are firing.
Injectors are usually live from the injector relay and earth out through the ECU. So with power on, check for +12V on the injectors.

Most of the other sensors etc - it'll try and run, just maybe not very well.

I checked all the basic stuff yes. Just no spark and ignition. All the other things looks fine. Power and grounds all are fine to. Also did a measurement on the cambus as is had a code in the instruments but the signal looks good to me.

[AudiS2700Hp]

Just to be sure. Does anybody knows what the minimal start rpm is to fire the injectors?

[AudiS2700Hp]

I'm pretty sure my ecu is bad so I send it today to actronics to have it checked out and hopefully a repair. Will keep you guys updated!