My buddy had his AEM EMS "tuned" by a shop. Before anything, they checked the base crank timing with a timing light and said it was 16. Pulls were made and later on they set the intake cam gear to +.5 and re-checked the base crank timing and it was 16.5 according to them. He said ok, close enough, and they did more pulls.

My question is...

With the AEM EMS, are you suppose to change the base timing number in the EMS so it matches what the crank is? Say his timing map at 16 psi and 8700 is 30 degrees. Could that actually be lower or higher because the AEM thinks the base is 16, when its really 16.5?

This is just a quick idea I had. We're trying to figure out why it made more power with timing that everyone is saying is too high.

 

yes the timing should be matched at idle or else timing will be wrong throughout the rev range.

if the ems thinks the timing is 16 at idle but physically the engine is at 16.5 then the timing will be .5 degrees advanced compared to the timing map in the ems all the time under all load and rpms. the great thing about the ems is it takes about a minute to re sync the timing.

 

If they really did go +.5 on the intake, it should be 17 on the crank right? 1 degree cam = 2 degrees crank.

We were hoping the difference would increase as the rpm's did. Oh well. I'll tell him to double check it.