Hi guys,


After having to modify my mapping due to vibrations and valve knock when it was really cold, i noow noticed that performance reduced and i had to go a couple of steps back.
None the lesse the weather has been stable for a while the only difference is that i just filled up a new tank, and immediately i noticed the difference.
So for me it's that the petrol station has switched from winter to summer quality.

What's your opinion on this?


Have a good one and keep it safe!

also temperature affects air density which affects amount of air inside cylinder

Our national fuel manufacturer has published the parameters of summer and winter diesel fuel on its website.
Only these differ:
Cetane number, not less:
summer 51
winter 48
Density:
summer 820-845
winter 800-840
Viscosity:
summer 2000-4500
winter 1500-4000
All other parameters are the same.

Hi Alex, Hi Jurebv,

Thanks for your reply.

I understand that the temperature changes the density and therefore the ignition timing and delay.

In this case I filled up the tank started the car drove a bit, restarted the car and immediately noticed the difference.
So in this case I'm sure it's not air temperature.

So from the numbers, what do I need to understand from this for timing? Higher cetane numbers need more temperature and pressure before it ignites, so this should retard the timing.
Am I correct?

topic name is diesel and you mention timing? there's no knock retard like in petrol nor timing, i dont think fuel is your problem , most likely some mechanical issue

No offense Jurebv but diesel is pure knock. That's the typical noise of a diesel engine.
You don't have the ignition that happens due to a physical ignition via a spark plug, but because of autoignition due to heat released by the compression of the air.

You do have an ignition delay after SOI and have to take timing into account witch is set by SOI and pulse with.



IE if you raise your railpressure over the entire range you shorten your pulse everywhere where you didn't raise your IQ and therefore you technically advance your timing.
I run on shell vpower diesel that already has an higher octane than regular diesel.

your diesel quality would have to be really really bad to have that kind of knock,which is basically not knock but missfire, if you raise your rail pressure and extrapolate your duration of injector it would not affect EOI, advancing SOI too much would have EOI before TDC which would result in negative torque