Bmcc Posted November 22, 2017 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!
Envy Posted November 23, 2017 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 .
Bmcc Posted November 23, 2017 Author 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?
Envy Posted November 23, 2017 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?
cliffcoggin Posted November 23, 2017 Posted November 23, 2017 Are you sure you have not mixed up two HT leads?
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