Intake Manifold Flaps

[aegerpa]

Looking for someone who has experienced RS5 error codes 2004/2005. Here's the story: I removed the rear intake tubes and shot a can of “intake valve cleaner” into the throttle bodies per instructions. Brand was STP. Wasn’t experiencing any obvious indication of carbon…just “why not”?! Immediately after, EPC light came on, codes checked and cleared but they come right back…2004/2005, Banks 1/2 Intake Manifold Flap stuck open. I had several thoughts about the cause and I’ve been working through them: 1) I dislodged enough carbon that the flaps stuck open. 2) I melted the flaps with the cleaner. 3) I knocked a vacuum hose or 4)some sensor wire loose doing the cleaner injection. Or 5) I somehow damaged the sensors with the cleaner.

So, I’ve confirmed the following…a) flaps move upon startup…I assume that is “closing them”. I also can move them with my finger reaching down under the vacuum motor actuator on the drivers side front. Engine vacuum is good. Good vacuum at the actuator; if I disconnect it the flap arm moves back, and the character of the idle shifts around, so I’m pretty sure they are actually moving. I feel like I’ve eliminated 1,2, 3…not sure yet on 4&5, but the actual sensors are way up front on the engine, so unless there is another connector or sensor back by the throttle bodies, I can’t see it being 4 either.

I’m not sure what to log to further diagnose. I tried logging Intake Manifold Runner Control but it just flatlined…car runs great, no other error codes, doesn’t seem to be down on power either at mid throttle or full bore. I’m NOT getting other error codes like Intake flap implausible signal, etc. that would suggest an electronic failure. Wonder if I should fog the intake with some more cleaner, but perhaps less aggressive, like Mass Air Flow sensor cleaner (yeah, I know we don’t have a MAF.)

Manual says I have to remove UIM to replace the sensors…I just used up my “wife grace” and “old man” soreness installing Michel's tranny cooler (shoutout to Michel for that’s awesome kit!) so I’m trying to avoid removing UIM right now, but…

Thoughts?

[aegerpa]

Ok, it’s obvious this isn’t a common problem! Perhaps a simpler question…does anyone know how the sensor works? Is it just a rotational device, or magnetic, or something else? Pretty sure I can see the sensor externally, but shop manual says the uim needs to be pulled to replace it, so I’m betting on the rotation…which suggests hitting it with cleaner didn’t damage it. More likely a connector somewhere…

[hahnmgh63]

The flaps are just move by the actuator at the end of the shaft, vacuum operated, controlled by the ECU based on RPM & Load. I can't imagine right off hand any sensor that would be damaged. I'm sure you've retraced your steps and checked every wire close to the Throttle body's which is what I think you mean by rear intake tubes. The sensors are G336 Bank1, G512 Bank2. The sensors just tell the ECU what position your manifold is in and when to start/stop the vacuum. The fault codes are telling you that the valves are most likely stuck open. Do you have Vagcom? Check Intake Manifold Flap, use Output Test, perform Basic Setting (Switch Ignition OFF between Output Test and Basic Setting).
Pulling off the intake manifold is a pain but not too difficult. You may need to pull it to check. Just remember if you do that the flaps need to be opened manually when you slide the intake manifold flap module back down otherwise they will be stuck close as they will be jammed by the intake guide vanes.

[aegerpa]

Thanks. Yes, I removed the intake tubes (hoses) at the throttle body to clean. I’ve looked for loose wires/ connectors without finding any.

Yes, I have VAGCOM. That’s how I read the codes and tried clearing. I tried to do the output test and the basic setting last night but got a message about “not allowed” or not authorized or someth8ng along those lines. I’ll try again with key off and on.

So, when I start the engine, the actuator arm definitely moves. If I pull the vacuum line off, it definitely moves back. So vacuum OPENS them? Sounds more and more like I have a bad wire some place that is not cutting the vacuum signal at the appropriate times…

[hahnmgh63]

When you tried the test with Vagcom, did it say no access due to Security? If so then you need to go to the Security tab first and enter the generated code, then go back and try again. Let us know if it works. My RS5 isn't running but I guess I could go give it a try on my S5, the 3.0t's have the same type of inlet flaps.