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Hi Andre or any one know why using MAP (SD) to idle a engine on bigger cam is better?
Can MAF still provide good idle on big cams if we adjust AFR richer and raise rpm higher or MAF just can't do that?
And why does maf suffer idle issue with cams and not Map (SD) ?
Typically a MAF will work just fine with mild cams. With larger cams though, particularly those with a lot of overlap, we see reversion pulsing at idle. This literally means that air can be forced back down the inlet track and back through the MAF sensor. This means the same air is measured multiple times giving a false airflow reading to the MAF. This can make it difficult to achieve stable idle when using a MAF. A MAP sensor is unaffected by this reversion and hence is preferable.
Can you give me example what cam is consider mild what is large so I will remember this in future and just not waste my time on tuning maf if i see large cams in cars.
In my own experience with EVOs, you're probably not going to run into trouble with the sort of cams that you would likely use on the street - For example cams such as the popular 272 Kelford or similar will work quite nicely on a MAF. With our drag builds we were using cams around 298/300 degrees advertised duration and these would be challenging at best to achieve good results on with a MAF. That being said I haven't had first hand experience as all our serious drag engines ran on a standalone ECU.