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Discussion Starter #1 (Edited)
Hi fellas,

regarding the 2007 a5 3.0 tdi manual gearbox engine. Ever since my ownership the rpm has always been unstable when in any gear or noticeable when cruising or decelerating, the rpm goes slightly up and down by 50-100 rpm. In addition, I've changed so many things on the car - clutch & flywheel, chains,both belts, all liquids, all filters, spark plugs.
From what I've read could be the PCV valve, however wanted to hear a few opinions before I jump into conclusions.
P.s - no poor gas mileage, no excessive oil leak, no smoke from exhaust. Car does shakes a little when cold in the first 5 mins. Also shakes when Rev In low rpm around 1000-1500
 

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Hello Ivo!! Sounds to me likely to be an air leak somewhere on the intake system allowing this uneven idling. BUT does not sound very serious mate so just go one small step at a time, you will find it eventually!!!!
 

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Discussion Starter #3 (Edited)
Hello Ivo!! Sounds to me likely to be an air leak somewhere on the intake system allowing this uneven idling. BUT does not sound very serious mate so just go one small step at a time, you will find it eventually!!!!
Appreciate the quick reply. Thank you 🙏

update: spoke to the mechanic that fixes my car. He said that in order to change the chains, he had to take out the engine, therefore he did take out all of the intake system and put it back in. Problem has always been current with the car and intake system wasn't the problem I guess.
 

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Hi fellas,

regarding the 2007 a5 3.0 tdi manual gearbox engine. Ever since my ownership the rpm has always been unstable when in any gear or noticeable when cruising or decelerating, the rpm goes slightly up and down by 50-100 rpm. In addition, I've changed so many things on the car - clutch & flywheel, chains,both belts, all liquids, all filters, spark plugs.
From what I've read could be the PCV valve, however wanted to hear a few opinions before I jump into conclusions.
P.s - no poor gas mileage, no excessive oil leak, no smoke from exhaust. Car does shakes a little when cold in the first 5 mins. Also shakes when Rev In low rpm around 1000-1500
Not trying to be funny but, i hope your mechanic didn't change the spark plugs in your 3.0 tdi...
Just out of interest, changing chains etc - was this done because of this issue or something else?
Just wondering if its worn engine mounts for shaking?
 
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Discussion Starter #5
Not trying to be funny but, i hope your mechanic didn't change the spark plugs in your 3.0 tdi...
Just out of interest, changing chains etc - was this done because of this issue or something else?
Just wondering if its worn engine mounts for shaking?
Spark plugs were definitely changed because 4 of them weren't working - Bosch brand.

I did the massive changing of chains, belts, etc because the car was close to 120k without having them changed ever and I had a very long journey ahead of me - 1200 miles, so I didn't wanna take any chances, having in mind the pandemic situation. I know it's a big argument whether chains last till forever or whatnot, but my friend has the same car, his chains snapped at around 120k, so again, didn't wanna take any chances.
I will check the engine mounts. Thank you.
 

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Spark plugs were definitely changed because 4 of them weren't working - Bosch brand.

I did the massive changing of chains, belts, etc because the car was close to 120k without having them changed ever and I had a very long journey ahead of me - 1200 miles, so I didn't wanna take any chances, having in mind the pandemic situation. I know it's a big argument whether chains last till forever or whatnot, but my friend has the same car, his chains snapped at around 120k, so again, didn't wanna take any chances.
I will check the engine mounts. Thank you.
Ok. No probs. That makes sense with the chains. I honestly don't know how long they will go on for, or how far people take the original chains.

You have a 3.0 TSI then if your mech is changing spark plugs? (the 3.0 tdi you mentioned is a diesel engine). And if hes changing spark plugs in a diesel, then that s a whole different conversation!

On a side note, my Mrs has a 2.0 TFSI TT. That does shake a little bit at idle. Performance is still great. Just not a smooth idle. I think its a TSI/ TFSI direct injection thing. Maybe giving the engine a clean (search walnut shell blasting for audi petrol engine) may make a difference?
 

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Discussion Starter #7
Ok. No probs. That makes sense with the chains. I honestly don't know how long they will go on for, or how far people take the original chains.

You have a 3.0 TSI then if your mech is changing spark plugs? (the 3.0 tdi you mentioned is a diesel engine). And if hes changing spark plugs in a diesel, then that s a whole different conversation!

On a side note, my Mrs has a 2.0 TFSI TT. That does shake a little bit at idle. Performance is still great. Just not a smooth idle. I think its a TSI/ TFSI direct injection thing. Maybe giving the engine a clean (search walnut shell blasting for audi petrol engine) may make a difference?
Well mine is the 3.0 tdi indeed. I've bought an engine and an injection cleaner, so I'll give it a clean and we'll see. 🙏
 

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I cant help it... i'm biting...........

You cant have a 3.0tdi and spark plugs. If you have 3.0 tdi you have a diesel. Do you mean you've had the glow plugs replaced, not spark plugs? There is no spark in a diesel engine as it is compression ignition.
TFSI/ FSI is petrol
TDI is diesel

I can't help be picky in semantics, its a throw back to my job.
What concerns me is if you do have a diesel and your mechanic says he's changed the spark plugs (do you mean glow plugs?).

Engine1.8 L TFSI I4
2.0 L TFSI I4
3.2 L FSI V6
3.0 L TFSI V6
4.2 L FSI V8
2.0 L TDI I4
2.7 L TDI V6
3.0 L TDI V6
Transmission6-speed manual,
6-speed Tiptronic automatic
7-speed S tronic semi-automatic
8-speed Tiptronic Automatic
Multitronic CVT
 

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Discussion Starter #9
I cant help it... i'm biting...........

You cant have a 3.0tdi and spark plugs. If you have 3.0 tdi you have a diesel. Do you mean you've had the glow plugs replaced, not spark plugs? There is no spark in a diesel engine as it is compression ignition.
TFSI/ FSI is petrol
TDI is diesel

I can't help be picky in semantics, its a throw back to my job.
What concerns me is if you do have a diesel and your mechanic says he's changed the spark plugs (do you mean glow plugs?).

Engine1.8 L TFSI I4
2.0 L TFSI I4
3.2 L FSI V6
3.0 L TFSI V6
4.2 L FSI V8
2.0 L TDI I4
2.7 L TDI V6
3.0 L TDI V6
Transmission6-speed manual,
6-speed Tiptronic automatic
7-speed S tronic semi-automatic
8-speed Tiptronic Automatic
Multitronic CVT
Yeah, sorry I meant glow plugs. English isn't my native language and I got the terminology wrong since it's the same term in my first language. To sum up, it's a diesel and I've changed 4 of the 6 glowing plugs since they weren't working.
 

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Yeah, sorry I meant glow plugs. English isn't my native language and I got the terminology wrong since it's the same term in my first language. To sum up, it's a diesel and I've changed 4 of the 6 glowing plugs since they weren't working.
Hey Ivor. No problem :)

I'm glad we got that sorted. I was worried that your mechanic was doing things that were not real (changing spark plugs in a diesel!) and you were being ripped off! But it sounds like you know ok.

Ok. So a 3.0TDI but rough/ rattle. What is it like at idle? Mine idles at 8-900rpm at first start. But will go down to 600rpm when warmed up. But it is smooth across the rev range.
You've changed injectors and filters. As Simon said it could be an air leak (this does affect petrols, not sure about diesels?). Any codes from a scan?
 

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Discussion Starter #11
Hey Ivor. No problem :)

I'm glad we got that sorted. I was worried that your mechanic was doing things that were not real (changing spark plugs in a diesel!) and you were being ripped off! But it sounds like you know ok.

Ok. So a 3.0TDI but rough/ rattle. What is it like at idle? Mine idles at 8-900rpm at first start. But will go down to 600rpm when warmed up. But it is smooth across the rev range.
You've changed injectors and filters. As Simon said it could be an air leak (this does affect petrols, not sure about diesels?). Any codes from a scan?
At idle, it is exactly the same as yours with the rpm range but it does pulse 50-100 rpm all the time. My mechanic said that they took off the intake system when they were changing the chains (because they took off the whole engine) and they were aware of the problem, they said they checked the intake system and there weren't any leaks.

A scan does show these faults:
7154 - Intake Manifold Flap Position Sensor (Bank 1)
P2015 00 [032] - Implausible Signal
Intermittent - Not Confirmed - Tested Since Memory Clear
Freeze Frame:
Fault Status: 00000001
Fault Priority: 2
Fault Frequency: 1
Mileage: 185469 km
Date: 2020.05.14
Time: 04:48:31

Engine speed: 810.50 /min
Normed load value: 15.7 %
Vehicle speed: 0 km/h
Coolant temperature: 84 °C
Intake air temperature: 24 °C
Ambient air pressure: 980 mbar
Voltage terminal 30: 11.680 V
Unlearning counter according OBD: 19
Engine speed: 810.5 /min
Vehicle speed: 0.00 km/h
Vehicle voltage terminal 30: 11680 mV
Intake manifold flap offset position open: 0.00 %
Intake manifold flap offset position closed: 0.00 %
Intake manifold flap position sensor: 4789.6 mV
V Sw Vlv st Mon B1-Bits 0-7: 00001000
V Sw Vlv st Mon B1-Bits 0-7: 00000000

7155 - Intake Manifold Flap Position Sensor (Bank 2)
P2020 00 [032] - Implausible Signal
Intermittent - Not Confirmed - Tested Since Memory Clear
Freeze Frame:
Fault Status: 00000001
Fault Priority: 2
Fault Frequency: 1
Mileage: 187258 km
Date: 2020.05.15
Time: 04:32:58

Engine speed: 862.00 /min
Normed load value: 17.6 %
Vehicle speed: 0 km/h
Coolant temperature: 63 °C
Intake air temperature: 25 °C
Ambient air pressure: 960 mbar
Voltage terminal 30: 11.720 V
Unlearning counter according OBD: 20
Engine speed: 862.0 /min
Vehicle speed: 0.00 km/h
Vehicle voltage terminal 30: 11720 mV
Intake manifold flap 2 offset position open: 0.00 %
Intake manifold flap 2 offset position closed: 0.00 %
Intake manifold flap 2 position sensor: 4701.8 mV
V Sw Vlv st Mon B2-Bits 0-7: 00001000
V Sw Vlv st Mon B2-Bits 0-7: 00000000

5496 - Intake Manifold Runner Control Bank 2
P313C 00 [032] - Movement Restricted or Blocked
Intermittent - Not Confirmed - Tested Since Memory Clear
Freeze Frame:
Fault Status: 00000001
Fault Priority: 2
Fault Frequency: 1
Mileage: 185195 km
Date: 2020.05.14
Time: 01:56:21

Engine speed: 1278.00 /min
Normed load value: 55.3 %
Vehicle speed: 77 km/h
Coolant temperature: 96 °C
Intake air temperature: 8 °C
Ambient air pressure: 1210 mbar
Voltage terminal 30: 14.220 V
Unlearning counter according OBD: 18
Engine speed: 1278.0 /min
Vehicle speed: 77.85 km/h
Vehicle voltage terminal 30: 14220 mV
Intake manifold flap 2 activation: 95.00 %
Intake manifold flap 2 feedback: 63.26 %
Intake manifold flap 2 output stage: -39.33 %
Coolant temperature: 96.5 °C
Engine speed: 0.00 /min
Normed load value: 0.0 %
Vehicle speed: 0 km/h
Coolant temperature: -40 °C
Intake air temperature: -40 °C
Ambient air pressure: 0 mbar
Voltage terminal 30: 0.000 V
 

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Definitely sounds like an air leak, check your air box and maf. Looking at the codes it seems like you also have a swirl flap problem. Check to see if the actuators are working ok and all the electrical connections are fine. If not you can try a repair kit or just have them mapped out from the ECU.
 

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Well said The_jargen. I think that diesel or petrol, if air is leaking into the system then that will provoke an uneven tick over/idle speed. You mechanic sounds sincere BUT have a very very careful look at the aircleaner box and hoses, even a tiny hole in an air hose can provoke this. Good Luck!!!
 
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