You are indeed correct, four electrodes. NGK plug finder shows ZFR6S-Q.Are the correct NGK plugs 408441140? They are 4 earth prongs, not 3
What plugs are you running Simon?Exactly 100% the same symptoms as me (@PlasticMac knows ALL about my issues) - I just replaced the fuel filter and it hasn't happened since, however I have yet to make a longer journey which is usually what brings it on (i.e hot engine more than 30 minutes continuous drive). My ProBoost arrived today, so reading your tale I am now extremely dubious it will sort me out![]()
Denso K20PBR-S10 were in it MacWhat is the part number of the Denso plug please?
Mac.
It'll be interesting to see what Denso plugs were in @Phil_B 's engine.Denso K20PBR-S10 were in it Mac
Just checked my last (large) service invoice from Nov 2023 - they listed 4 x ZFR6S-Q which a quick part search matches to an NGKWhat plugs are you running Simon?
Mac
If I may, higher octane generally allows to use more timing advance, not less (as the lower self ignition characteristics of high octane fuel will make for a controlled combustion rather than disorganized detonation even if sparked earlier in the cycle when the piston is still compressing)The EML flashing, rather than coming on, and staying on, is because the trigger for the EML is a transitory condition, misfire, or knocking.
The DTC is logged, but EML clears, when the condition clears.
The "condition" seems to be related to the octane rating of the fuel.
Higher octane fuel, typically, allows the timing to be retarded, with the spark occurring closer to TDC.
In retarding the ignition, comes the risk of the fuel self combusting before the spark, pre-ignition by compression ignition. This is a possibility here, I think.
When were the plugs last changed, and are they the correcttriplequad electrode type, (NGK preferably)?
Mac.
Edit: Could also be bad fuel has fouled the plugs.
Had similar, although it was only leaking under load.On an unrelated, I mentioned a while back that occasionally I get the big red oil sign light up, even though I have decent, and enough oil in the engine. I thought it was the oil level sensor.
Its not, it's the pressure sensor. And it's leaking. From the middle of the sensor, not the fitting thread.
In all my years of driving, I've never seen that before.
I thought retarding the ignition means delaying the spark, so it occurs closer to TDC on the compression stroke, which using higher octane fuel allows.If I may, higher octane generally allows to use more timing advance, not less (as the lower self ignition characteristics of high octane fuel will make for a controlled combustion rather than disorganized detonation even if sparked earlier in the cycle when the piston is still compressing)
Retarding is indeed as you describe: bringing the spark closer to TDC (i.e. less advanced with respect to TDC), but it is the conditions for doing so that we differ on (and regarding which I respectfully stand by my argument)... for example some engine ECU would take out some advance when experiencing detonation (say using fuel with less octane). The confusing thing may come from the different causes of detonation (e.g. hot spot within the chamber), but if I understand this correctly retarding when using lower octane has the purpose of avoiding faster than normal combustion too early in the cycle (more octane makes for a more consistant, controlled combustion, with a same flame front speed over the whole range of RPM, and as a by product allows for more advance for optimal tuning).I thought retarding the ignition means delaying the spark, so it occurs closer to TDC on the compression stroke, which using higher octane fuel allows.
Advancing the ignition means the spark occurs earlier in the compression stroke, allowing use of lower octane fuel.
Have I got my retard and advance the wrong way around? Sorry if so.
Mac.
I didn't know that.Higher octane means a slower and more predictable burn, so you can “advance” the timing by firing the plugs earlier, further from TDC.