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Misfiring - Spark plugs

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#1
Burner1144

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Hi all,

RS started to misfire today. So pulled the plugs to have a look see. It’s just come out of service at 65000kms and plugs were not replaced.

Found some signs of arcing on one of them... looks like porcelain is actually cracked.
Attached File  IMG_0677.jpg   269.85K   36 downloads

What concerns me is these plugs look like they burning pretty lean from the color? I am running 10% ethanol because if I run our 95RON here in South Africa I have heard some detonation especially pulling away from a stop. Running the eth has completely resolved the detonation but worried may be a bit lean at 10%
Attached File  IMG_0676.jpg   559.4K   35 downloads





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#2
Fivepotfan

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Hi all,

RS started to misfire today. So pulled the plugs to have a look see. It’s just come out of service at 65000kms and plugs were not replaced.

Found some signs of arcing on one of them... looks like porcelain is actually cracked.
attachicon.gifIMG_0677.jpg

What concerns me is these plugs look like they burning pretty lean from the color? I am running 10% ethanol because if I run our 95RON here in South Africa I have heard some detonation especially pulling away from a stop. Running the eth has completely resolved the detonation but worried may be a bit lean at 10%
attachicon.gifIMG_0676.jpg





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If it helps as a visual comparison, these plugs were from my PFL car at 10K miles. Air fuel ratio (AFR) was running nicely between 11.5 and 12 and the plugs are pretty much as you would expect to see (colour wise).

 

Attached File  IMG_2781.JPG   20.05K   18 downloads


now driving a 'Daytona Lite' FL car.


#3
RS3Dell

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Hi all,
RS started to misfire today. So pulled the plugs to have a look see. It’s just come out of service at 65000kms and plugs were not replaced.
Found some signs of arcing on one of them... looks like porcelain is actually cracked.
attachicon.gifIMG_0677.jpg
What concerns me is these plugs look like they burning pretty lean from the color? I am running 10% ethanol because if I run our 95RON here in South Africa I have heard some detonation especially pulling away from a stop. Running the eth has completely resolved the detonation but worried may be a bit lean at 10%
attachicon.gifIMG_0676.jpg
Sent from my iPhone using Tapatalk


Your plugs look old with high milage on them also the cracked porcelain may verify this,going by the soot around the plug thread & the non bleaching of the plug tip i don't think it running lean also bad fuel can cause the pinking problem under load so its best to get your fuel from a major fuel outlet.

Plugs change is at 19k miles so a good starting point is to do this,.

I understand a standard RS3 can run on 95ron but there will be a drop off in performance.

Also you can add the maximum of 10% ethanol as stated in the handbook.

Dell.

Edited by RS3Dell, 08 December 2018 - 12:05 PM.


#4
Burner1144

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Thanks For the feedback guys.

Yeah I saw the owners manual re the ethanol

Booked it back into dealership to change the plugs.

a3f31a79082bea93b656f9b9852eab43.jpg




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#5
Jacques_RS3

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Hi Man, nice to see a fellow South-African .... there are a few things to look out for on these cars ... believe me I have had almost everything go wrong with my RS3 since I had it .... one thing you definitely need to keep an eye on is the AFR's if the car runs lean then you might have fueling problems. Mine ran lean and then popped the motor ... Bad fuel and clogged injectors is what kill's these cars.

 

I replaced the fuel filter recently and was shocked at what came out of it .... Audi does not change it so it's possible you still have the old one on the car, I now change it on a regular basis.

 

Cheers



#6
Burner1144

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Thanks for the heads up Jacques,

It’s at another dealership now hopefully getting sorted out. I got myself a genuine vcds and ran a scan before it went in.

Low fuel pressure regulation.
EVAP emission control - Incorrect flow
Misfire cyl 1
Knock sensor 1 - Malfunction
Fuel rail/ system press - too low

I also logged fuel pressure which showed requested 24bar at idle and actual was at 23,9 bar. Car off, ignition on at operating temp (88deg) pressure went up to 40bar over 10min. So I’ve asked them to check the pickup and HP fuel pumps with the sensors etc.

It seems the dealership has picked up the same errors so they testing and checking. The knock sensor malfunction is alarming too!

They called the Prev dealership to ask why they never replaced the plugs at its last service at 65000kms, as they should be done every 30000kms. They said they only need to be done at 90000kms!!

So the plugs in the pics have probably never been replaced. Current mileage on 66000kms.

I’ll be making sure fuel filter is done now too, then let the logging begin...

Thanks a mil...




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Edited by Burner1144, 12 December 2018 - 08:12 AM.


#7
Burner1144

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So found the culprit for my low fuel rail pressure.

Looks the like the HP line feeding the injector rail has sprung a leak. Gradually started smelling fuel vapor in the cab, I guess as it was worsening the vapor smell was getting worse.

So back to dealership it goes.... which is now going to be a mission as they will need to come fetch it. No way I’m driving it with that mist floating about beneath bonnet.

401376fa3f8937d0c6664f81018cc903.jpg


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