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Ignition timing vs Engine load

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Hi All,

I datalogged my car on the road and found some knocks here and there, but they are mostly in the mid-load areas of the ignition map. So I retarded the ignition timing in the areas that were knocking (according to the datalogs) and now i have an ignition map that has higher advance in the full-load column than the mid-load columns. Has anyone encountered this kind of ignition map layout or is there something that i should pay attention to?

Appreciate any feedback from you guys. Thank you.

If you're using MAP as the load axis for your ignition table then this situation would be pretty rare and I'd be suspicious of your knock control data logging. I have seen this scenario on engines mapped off TPS though where it's been necessary to retard the timing slightly at part throttle while ramping it back up a little at WOT.

Hi Andre, i too suspect the knock control maybe a tad sensitive. Best way is to cross reference the readings with an audible tool?

In my case, I am using MAP as load reference. But it seems to behave like what you described in your TPS case.

I would recommend using audio knock detection to confirm what your ECU is doing.

Hi Andre,

Which is the reason or theory to have a little more ignition advance at wot (high load) than at part throttle on TPS mapped engines.

Thanks Andre. I'm thinking to get a new pair of cams in. I expect I will have to re-do the steady state tuning all together, am i right?

If you're changing the cams then this will have a pretty big impact on the engine's VE and hence the optimal ignition timing is likely to be different so yes, you will need to touch up the ignition table.