A3 BMN Engine cutting out

[electronicstuff]

Hi, I have developed a fault with my A3, The engine code is BMN

The car is cutting out at around 2400 rpm, when this happens the revs drop and you can hear a relay clicking from under the dash. This results in kangarooing effect most of the time, but sometimes just dies completely, will normally restart fine, This also happens when parked up and reving the engine.

There are no dash lights and when scanned with vcds there are no codes.

The fact it seems to happen at 2400 rpm and the relay clicking, it seems as if something is causing the signal to the relay to be turned off thus shutting the car down, yet once below that rpm range it will come back on. Dash remains as normal, just like the car is still running.

At first I thought it may be a fuel issue and replaced the in tank lift pump and fuel filter, its not like an over boost issue, kinda feels like the fuel injectors are being shut off, but like I say no error codes in vcds or dash lights, drives fine so long as you keep the rpm below 2400 which is hard to do (can't accelerate quickly and no fast roads)

I hope someone on here has an idea of whats going on as I'm at a loss now, tia

 

[electronicstuff]

bump

Any ideas?

 

[abmat]

Try and identify the relay, then that could point to the fault.

 

[electronicstuff]

Try and identify the relay, then that could point to the fault.

The relay is for the lift pump that clicks, tried removing the relay and car dies just the same when reving parked up, doesn't splutter like low fuel, just cuts out and stalls

 

[abmat]

You tried replacing the relay?

 

[electronicstuff]

You tried replacing the relay?

Ok so I've just tried replacing the relay, no difference, seems like something is not happy once you are at the 2400 rpm rev range and kills the engine, its such a weird fault and so difficult to diagnose with no error codes.

I have booked it into the local stealership for Thursday this week, £60 first hour and £120 per hour afterwards, just hope they can find the fault in the first hour

 

[electronicstuff]

To anyone following along or experiences the same problem, turned out to be the engine speed sensor (G28) Crank sensor, after checking fuel, timing etc they managed to get it to throw this code, sensor replaced and so far it's working ok, fingers crossed it stays working.

It was interesting in how it behaved as I've experienced the same sensor failing before on a pd140 bkd engine and it was completely different, just long cranking to start the car, then kept running just limited to 35oo rpm but never cut out like this one did.