Rough idle and multiple codes

Tiny
DIVIDES
  • MEMBER
  • 2010 AUDI A5
  • 4 CYL
  • TURBO
  • 4WD
  • MANUAL
  • 186,000 MILES
Has several codes and misfiring:

P2279/
p050700/
p30100/
p30200/p
30200/p
30400

Is it possible carbon build up?
Do you
have the same problem?
Yes
No
Sunday, November 7th, 2021 AT 2:53 PM

47 Replies

Tiny
AL514
  • EXPERT
Hello, can you be clear on the codes again, are you saying, P2279, P0507, P0301, P0302 and P0304? Any Codes P0301-P0304 are cylinder misfire codes per cylinder, i.E. P0301 Cylinder #1 Misfire etc.
Also, do you have access to your own scan tool?
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Monday, November 8th, 2021 AT 8:51 AM
Tiny
KASEKENNY
  • EXPERT
Just to add to this, if you have misfire codes on multiple cylinders and the P2279 which is an air intake temperature code which is most likely caused by an air leak then we need to start with this.

More than likely you have a leak on the charged air side of the turbo. Basically, if you are losing pressure from the turbo to the intake it will cause a rich condition and you can have a misfire.

Basically, it thinks there is a certain amount of air coming in and matches that with fuel but if there is a leak then you will not have that much charged air and so it be a rich condition.

https://www.2carpros.com/articles/engine-misfires-or-runs-rough

Let's monitor the o2 sensor data and see if you are on the rich side and then use soapy water on the charge tube to look for bubbles.

If this all checks out, then I am attaching the testing for this code which is what we need to run through.

Lastly due to the rough idle, we should check for a vacuum leak. This is a similar test but here is a guide for checking for a leak:

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Let us know what questions you have.

Thanks
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Monday, November 8th, 2021 AT 12:22 PM
Tiny
DIVIDES
  • MEMBER
Makes sense. Thanks to you guys.
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Monday, November 8th, 2021 AT 12:28 PM
Tiny
KASEKENNY
  • EXPERT
No problem. Let us know how it works out. Thanks
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Monday, November 8th, 2021 AT 12:49 PM
Tiny
DIVIDES
  • MEMBER
First thing I did was wash the motor, there is so much oil/dirt around the coils, there may be oil in the wells due to cover gasket, have not checked yet. Deleted all codes, first one's came back as misfire coil 4 and p0070 ambient air temperature circuit.
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Wednesday, November 10th, 2021 AT 1:11 PM
Tiny
AL514
  • EXPERT
Ambient Air Temperature Sensor is labeled the Outside Air Temperature Sensor. This is going to be a 5-volt sensor with ground. I'll put up the diagrams for it.

https://www.2carpros.com/articles/how-to-use-a-voltmeter

https://www.2carpros.com/articles/how-to-check-wiring
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Wednesday, November 10th, 2021 AT 1:47 PM
Tiny
DIVIDES
  • MEMBER
Yes, it's the only hard code I see. I switched coils and now it says 2 instead of 4, so the rough idle is definitely at least caused by this sensor, may be other things but it's a hard code.
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Wednesday, November 10th, 2021 AT 2:42 PM
Tiny
AL514
  • EXPERT
But this is the first time you've gotten this code, correct? It's strange those others would disappear and a completely different one show up. How is the wiring harness on this thing, you don't notice any contact points where it may have rubbed threw the harness at all? On this Outside Air Temp Sensor, you should have 5-volts on the green/white wire and the other green/brown wire is a shared ground circuit. If you unplug the sensor and just lightly touch the pins, never jam a multimeter lead into a connector, you should have 5-volts with it disconnected. Thats it 5-volt reference wire (or feed). These sensors are usually on the front of the car, most of the time in the front grille area. You'll be able to identify it by its wire colors. This code is for a circuit issue. If you're missing its 5-volts, then there may be a wiring issue, corroded connector, etc. That would explain the other random codes. And by switching the coils around you've identified that it's a bad coil causing that misfire. Smart move by the way, moving that coil.

https://www.2carpros.com/articles/how-to-use-a-voltmeter

https://www.2carpros.com/articles/how-to-check-wiring
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Wednesday, November 10th, 2021 AT 2:57 PM
Tiny
DIVIDES
  • MEMBER
No, this code was among the ones that were there before. And for now, most of them disappeared, but they may reappear. I will check on the sensor.
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Wednesday, November 10th, 2021 AT 3:06 PM
Tiny
AL514
  • EXPERT
Okay, it may be like Kenny said, the turbo boost pressure is leaking and you're not getting other codes because you're just not driving it right now, The P2279 is an Intake Air leak code, and definitely can be coming from the turbo leaking into the intake. We call vacuum leaks "false air" because the ECM doesn't see them, but the oxygen sensors will and the ECM will increase fuel due to that, therefore causing a rich misfire.
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Wednesday, November 10th, 2021 AT 3:08 PM
Tiny
DIVIDES
  • MEMBER
Very possible. I only started it for few minutes, I can hear the turbo when revving the motor. Hopefully, it's not carbon build up as I do not like doing blasting, but with 186,000 its possible. Not sure where all the oil came from on top of the valve cover, not side where it should leak. Maybe from filling oil during these years and some seeped under the cover.
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Wednesday, November 10th, 2021 AT 3:10 PM
Tiny
AL514
  • EXPERT
Can you post a decent picture of it? Is it near the oil supply line for the turbo? In yellow is the supply line and red is the return line.
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Wednesday, November 10th, 2021 AT 3:13 PM
Tiny
DIVIDES
  • MEMBER
And spark plug looks okay, not wet or dark.
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Wednesday, November 10th, 2021 AT 3:18 PM
Tiny
DIVIDES
  • MEMBER
I think the sensor is on the intake side above the throttle body. Checked it with my probe and got ground and 4.5 number. Also cleaned it out. Cleaned MAF as well and checked on air filter. Checked turbo boot and is ok. Used water and soap sprayed everywhere around hoses, intake, nothing changed. Lifted the oil cap to see if its maybe PCV, bit it's easy to remove. Deleted codes and only got them all back under pending code, only one that keeps coming back as stores is the air sensor. Pending codes are misfires 1-4, which is expected when engine idling this rough. The rough idle is only when left idling, once I give it a touch of gas everything smooths out.
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Thursday, November 11th, 2021 AT 6:57 AM
Tiny
DIVIDES
  • MEMBER
Also found this PCV diaphragm busted but doubt it can cause all of that.
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Thursday, November 11th, 2021 AT 7:32 AM
Tiny
DIVIDES
  • MEMBER
Here you go.
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Thursday, November 11th, 2021 AT 7:32 AM
Tiny
DIVIDES
  • MEMBER
I changed it, made no difference. Also noticed that the fan is on and on high when A/C is off and car is cold.
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Thursday, November 11th, 2021 AT 8:19 AM
Tiny
AL514
  • EXPERT
Something else I noticed that is strange, are those live data readings with the car running? Because all your fuel trims are reading 0, which is not good, either the scan tool is not able to read all the data, or the ECM doesn't have full control of the fuel system. The sensor on the Intake is the Intake Air Temperature sensor, the Outside Air Temperature sensor is ambient outside air used mostly by the A/C system. Thats what the p0070 code is for, so you had 4.5 volts with the Intake Air Temperature sensor unplugged? that's a little low for the 5-volt reference circuit,
So, what are all the codes you're getting right now? pending or not.
the fan issue may be because of that ambient air temperature sensor being out of range, since it's part of the A/C system.
Go down to the APP sensor on the gas pedal and just check to see what the 5-volt reference is down there. On that sensor, (its 6 wire) you should have two 5-volt ref feeds.
Also looking at the Front 02 sensor, which is a wideband sensor is reading 0.980mA, that's indicating a lean fuel mixture, so that's still pointing at a vacuum leak here. Usually for a vacuum leak like this that you couldn't find with soap and water, i would use a smoke machine on the intake, I'm assuming you don't have one?

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge
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Thursday, November 11th, 2021 AT 8:29 AM
Tiny
DIVIDES
  • MEMBER
It just says 4.5 didn't make a beep or a green light. All pending are misfires on all and the p0070. I will check on the pedal sensor.
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Thursday, November 11th, 2021 AT 8:53 AM
Tiny
AL514
  • EXPERT
I'm not sure how accurate these numbers are but I do see a Short-Term fuel trim bank 1 sensor 2 of 99%, depending on how this ECM calculates its fuel strategy, either that's a lack of correct data, or the ECM is adding fuel to a lean mixture. The FRP (fuel rail pressure) looks within spec for idle, it should go up to 2,000PSI with higher RPMS.
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Thursday, November 11th, 2021 AT 9:07 AM

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