1.8T missfire - yes again!

TT Tim · 31st January 2021, 10:26

I know this has been asked a million time, but I just wanted to check, for my own peace of mind.

Just got this from TOAD:

P1300: Misfire detected sufficient enough to cause Catalyst Damage

P0303: Cylinder 3 misfire detected

I'll add this is under load, can drive on gentle throttle without any problem.

I'm looking at coil pack as leads were changed, and plug gaps checked. As this is so specific I don't think it's FFS - Agreed?

Thanks

Tim

planenut · 31st January 2021, 11:14

I'd certainly consider the coils before ffs. Check out the wiring and connectors, good luck. You could clear the codes, swap the coils, run it again and see if any fault has changed cylinder?

COLVERT · 31st January 2021, 13:30

Failing under load is quite often because a plug gap is too large or a plug is nearing the end of its life.

Under load the cylinder head pressure becomes so great that its easier for the spark to track down inside the plug than jump the gap.--Hence the misfire.

31st January 2021, 10:26	#1
TT Tim Regular poster Rover 75 Tourer Join Date: Feb 2018 Location: Brook, Ashford, Kent Posts: 61 Thanks: 18 Thanked 40 Times in 6 Posts	1.8T missfire - yes again! I know this has been asked a million time, but I just wanted to check, for my own peace of mind. Just got this from TOAD: P1300: Misfire detected sufficient enough to cause Catalyst Damage P0303: Cylinder 3 misfire detected I'll add this is under load, can drive on gentle throttle without any problem. I'm looking at coil pack as leads were changed, and plug gaps checked. As this is so specific I don't think it's FFS - Agreed? Thanks Tim

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31st January 2021, 11:14	#2
planenut Regional Secretary Rover 1.8T Tourer Join Date: May 2007 Location: Heathrow Posts: 6,948 Thanks: 1,551 Thanked 2,036 Times in 1,264 Posts	I'd certainly consider the coils before ffs. Check out the wiring and connectors, good luck. You could clear the codes, swap the coils, run it again and see if any fault has changed cylinder?

31st January 2021, 13:30	#3
COLVERT This is my second home R75 Saloon. Join Date: Feb 2009 Location: France/or Devon. Posts: 14,003 Thanks: 3,851 Thanked 2,167 Times in 1,816 Posts	Failing under load is quite often because a plug gap is too large or a plug is nearing the end of its life. Under load the cylinder head pressure becomes so great that its easier for the spark to track down inside the plug than jump the gap.--Hence the misfire.