Bosch MED17.9.63 Ignition and VVT

Hi Andre,

I am currently tuning a Bosch MED17.9.63 and I need some help figuring out which of the ignition timing and variable cam timing maps to make my changes to.

For the ignition timing they are separated into 4 tables. Two are labelled optimal ignition timing and two are labelled base ignition timing. Do you know which of these I should change? Also, one of the base timing maps has all negative numbers which is a bit odd.

For the variable cam there are three tables. One has a flat value of 29 set across the entire table, one has all negative numbers and one more resembles what we would be accustomed to for cam timing map on the intake cam. My gut is telling me only change this one, but yea hoping someone with more specific knowledge can chime in.

Hi, in order to give the correct advice I would need to see the exact maps. My rule of thumb is to adjust the timing table I believe it to be using a lower target number. Log this to confirm the values in the adjusted tables are represented in the data log. Not knowing what engine configuration you have makes it hard to give advice on cam timing. If there is only one table that would suggest it has only adjustment of one camshaft. Try changing these to a single value somewhere in the middle of the range and then log the cam position. If the values reflect the target in the map then you are adjusting the correct map.