Flashing engine warning light?

4.0 V8 40v biturbo TFSI - 553 bhp
4.0 V8 40v biturbo TFSI - 597 bhp (Performance)
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Daveperc
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Flashing engine warning light?

Post by Daveperc » Tue Oct 15, 2024 9:23 am

On Friday the EPC light came on shortly after I entered the motorway and a few miles further on I became aware that under light load the car was very rough under light throttle – a misfire possibly on one or more cylinders? Also noted that fuel consumption was exceptionally good (30MPG or so!) so it could be fuel related. Once stopped for a few hours the problem, and the warning symbols, were all cleared, though on the drive home the “you have a warning” symbol did come on part way through the journey.

On Sunday no warnings but several miles into the journey, as I rounded the righthand bend M3 to M25 the engine warning light flashed for about 10 secs, the “you have a code” light came on – but no physical symptoms. Again this cleared when stopped for the return journey.

So, any thoughts on likely (and hopefully simple) solutions?

Yes, I know the next step is read the codes - only I don't have the reader, and am very busy, and my favourite tuner simply can't fit me in!

Tadass910
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Re: Flashing engine warning light?

Post by Tadass910 » Sat Oct 19, 2024 4:28 pm

Go to audi

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Daveperc
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Re: Flashing engine warning light?

Post by Daveperc » Sat Mar 22, 2025 4:07 pm

Got this sorted! :-)

Actually I had two problems, both fuel delivery related.

The low revs misfire seems to have been a result of worn seals on the HPFP's - they have done nearly 100K miles so probably not surprising.

When Doug Dyno'd the car we realised that 90 of the ponies had run off and that the problems are at the top rev end - investigation suggests that this is the LP fuel pump (in the tank) not getting enough fuel through to the HPFP's. The LP pumps appear to be on back order here in UK so it will be a trip back to drop the tank and replace the pump.

Once again - well found MRC :-) I'm still running above standard power, but want to get back to my full 700+!! :redrs4:

morski
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Re: Flashing engine warning light?

Post by morski » Tue Mar 25, 2025 3:55 pm

What year is your car? some pumps are availble depending on year etc.
The pump can be replaced from under the seat, No need to drop the tank

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Daveperc
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Re: Flashing engine warning light?

Post by Daveperc » Thu Apr 03, 2025 4:23 pm

OK - second day at MRC. LP fuel pump duly changed out and car onto Dyno.

First observaton was that my map was an early one so Doug did a full update and also on the box. After a lot of tweaking we found that we were still 50 or so HP short, and we get quite a lot of oil smoke at WOT, and have concluded it's probably the PCV which hasn't been touched from new. Very frustrating as we had the front end off only a few weeks ago :-(

Will get added to the list next time the car goes in.

New map is even smoother and more responsive in mid range than it was before - and TBH I only miss 50HP very occasionally! Still, in the words of the Byrds: !I'm gonna catch that horse if I can!"

Dave

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