Very strange problem

[Scatman]

Hi,

I'm hoping someone can shed some light on this one!

My EPC light came on this evening and was quickly followed by the CEL. So, I hooked up VCDS and the code was P2015 manifold flap position implausable intermittent. I reset the code then I ran output tests on airbox flap and manifold flaps.... all moving perfectly. I plugged out everything and started the car... lights back on again. VCDS in,, checked codes and same code again.... cleared it... started car... lights still on.

Now this time I hooked up VCDS, checked codes and "No Fault Code Found"! but the engine and EPC lights are still on. Disconnected and reconnected VCDS a couple of times (also turning off ignition etc) and still no fault code found but lights remain on.

Why would this be happening? Is it possible the ECU has crashed in some way?

Thanks!

[adsgreen]

Have you checked both ecus?

[Scatman]

Hey

I just plugged in by the bonnet release handle... clicked on 01 Engine option and selected 02 Fault Codes.... it then did the check. How do I get into the 2nd ECU?

(also to update: went for a drive and EPC light went out... CEL still on)

[wellzieRS4]

I think its on drivechain then engine 2

[adsgreen]

There's another menu for engine unit 2. Codes are logged separately.
I think from the main screen 01-engine is ecu 1 and 11-engine 2 is ecu 2.

Iirc it's not on the main default screen but drivetrain (or drivechain if you use an iPad/iPhone)

Epc is an audi light and will be more responsive to faults going away.

[Scatman]

great... thanks for that! I'll try it first thing tomorrow....

Although with the initial code at p2015 I'm beginning to suspect that I might need a decoke...

[wellzieRS4]

[quote="adsgreen"]There's another menu for engine unit 2. Codes are logged separately.
I think from the main screen 01-engine is ecu 1 and 11-engine 2 is ecu 2.

Iirc it's not on the main default screen but drivetrain (or drivechain if you use an iPad/iPhone)


No ipad/iphone just me being a bit dim

[adsgreen]

You could have got away with that - I'm lethal for sending out dodgy emails and text's due to the iphones uncanny ability to replace innocent stuff with very odd replacements

OP - I suspect that the implausible signal is either down to a vac leak, solenoid or a sensor failing.
Coke can bugger up the tumble flaps but the other options above just as if not more likely.

[Scatman]

Hi Adsgreen,

Logged into Ecu 2 this morning and code P2020 for tumble flaps on the other side was listed as implausable signal. Cleared the code and now both EPC and CEL lights are off and the car is running perfectly.

I performed the airbox flap and tumble flaps output tests again and they're working fine even 20 minutes after engine shut down so it doesn't look like there is any vacuum leak or issue with solenoid....

hmmmmmm.... fingers crossed the lights will stay off and there'll be hassle free happy times ahead!

Thanks for the advice..

[adsgreen]

Mine did the same.
First was a once off - reset everything and it was fine.
Few months later light back on (they should have called it the "Misery" light 'cause that little orange lamp ruins your day). Reset but this time was very persistent and would almost certainly come back on as soon as over 3k rpm (the flap change over point).
Ran some output tests... sometimes it worked fine others the solenoid just clicked. could move them by hand just unreliable with the solenoid. For me it was a new manifold to resolve.

The fact you're getting both banks reporting the flap error suggests a common problem as it's unlikely that coke is affecting both banks at the same amount at the same time. You'd expect one bank to stick first - esp as if one actuator doesn't move then the vac pressure on the other will be every so slightly higher.

Either there is a fault with the vac system - unfortunately the tests are a bit hit n miss sometimes. The best way to test them is with a vac gauge and hand pump. you can unplug each system (power flap, exhaust flap, manifold flap, secondary air system) individually and test using Vag Com whilst looking at specific vac readings.

It's also good to log the actual flap position and requested flap position to see how well they are moving. They may be moving but not enough for the tolerance in the ECU.