Bmcc Posted November 22, 2017 Share Posted November 22, 2017 Firstly hello! I recently bought an s3 2011 and decided to change the spark plugs (ngk pfr7s8eg). Car now runs like crap. idle bounces and it makes a rattly sound at the right side of engine. pulled plugs 3 and 4 with 3 looking sooty on the insulator 4 looks ok. Have i manged to break one of the ignition coils? Have i done something much worse? plugs torqued to 20lbs per foot. help appreciated! Quote Link to comment Share on other sites More sharing options...
Envy Posted November 23, 2017 Share Posted November 23, 2017 Soot on an insulator would suggest poor plug seating - hope it's not cross threaded. The rattly sound could be blowing out of the cumbustion chamber. If it is blowing it would run uneven too . Quote Link to comment Share on other sites More sharing options...
Bmcc Posted November 23, 2017 Author Share Posted November 23, 2017 Thanks for getting back to me. The plugs for 3 and 4 came back out and went back in fine so I don't think they are cross threaded, all the plugs went in no problem. I could stick the old plugs back in a see if it runs ok. I have VCDS and although the check light is not on I get this for the engine (checked this morning): 1 Fault Found: 000256 - Mass Air Flow Sensor (G70) P0100 - 004 - Supply Voltage Freeze Frame: Fault Status: 01100100 Fault Priority: 2 Fault Frequency: 1 Reset counter: 255 Mileage: 71730 km Time Indication: 0 Freeze Frame: RPM: 0 /min Load: 0.0 % Speed: 0.0 km/h Temperature: 12.0°C Temperature: 10.0°C Absolute Pres.: 970.0 mbar Voltage: 11.938 V Readiness: 0000 0000 Any one know how to test the MAF harness? Quote Link to comment Share on other sites More sharing options...
Envy Posted November 23, 2017 Share Posted November 23, 2017 I would look at cleaning up electrical contacts and connections first - MAF would normally affect general running rather than misfire http://wiki.ross-tech.com/wiki/index.php/16484/P0100/000256 Could be a red herring as I still would not expect to see soot on a new Plug - in fact any plug... You have any way to check if there has not been a helicoil fitted before? Quote Link to comment Share on other sites More sharing options...
cliffcoggin Posted November 23, 2017 Share Posted November 23, 2017 Are you sure you have not mixed up two HT leads? Quote Link to comment Share on other sites More sharing options...
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