406 SV recurring random misfire code P0300

davo8

davo8

Member
Fellow Frogger
Joined
Nov 2, 2010
Messages
98
Location
NSW
Hi Folks,
D9 SV auto with 160000Ks. Started throwing misfire codes and going into typical failed coil mode (rough running - no power - eco pollution message on screen) about 6 months ago which automatically cleared after pulling up and restarting. It runs beautifully between these random and annoying events. I have checked plugs, replaced all coils, replaced an overdue fuel filter, dismantled and cleaned all 6 injectors, checked all vacuum lines, resealed intake manifold. Code alternates between Cylinder 1, 3 or 5. I have just got P2000 and sorted it, so have the potential to diagnose deeper. Wondering if it could be a Lambda or Crank position sensor etc. Any help or suggestions would be much appreciated.
 
Plugs don't last forever, and the ES9J4S is not a lawn-mower engine - why not just replace all the plugs?

My similar D9 (but with twice the kays) was doing this sort of thing when I was trying to get away on a trip. Wanted to get it right before putting the manifold back on, so went off to all the local auto-spares shops, but none had the right NGK plugs (I only use Iridium these days in good engines). Fitted a set of Autolite iridium plugs from SuperCheap and all has been fine ever since. The Autolites are significantly cheaper than the NGK, and may not last as long - too soon to tell - but I stopped losing cylinders.

My D9 SV really is my car of choice to get me places reliably, comfortably and quickly.
 
You'd look at plugs, coils, and injectors in that order for that misfire fault, which is detected by the upper lambda sensor. New plugs is the first thing to do.
 
Thanks for that. NGK Iridiums have done about 60K, look fine, but would be 10 years old. I used to be able to get them in from the US for about $A7 each with standard post. The new coils are all Delphi but no longer have the white resin top. I think they are now made in China. Still love the drive, but this has certainly tested the relationship. First time in 13 years that the bride has even suggested selling her pride and joy.
 
Fitted new set of Bosch platinums. No change. Searching for a poor wire/connector somewhere as I give things a wiggle and it clears ... for a while.
 
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