Has anyone experienced knocking when tuning Mivec? I just want to know because I'm about to tune for Mivec and wanted to know what values were too much. I could always do a trial and error tune and then test for knock but I thought I'd ask here first.

 

I have noticed too much MIVEC advance can induce some extra knock. Usually around spoolup and top end of the RPM Range (5500 +).

 

At what value were you noticing knock began to happen? I'm going to take a stab and say 26-27*

 

6000+ for me; at times cruising i the late 3000+

 

I am currently running 91oct with a stock fuel map and less aggressive timing. Anything over 27 advance on the MIVEC will cause 7+ counts of knock during spoolup no matter how much timing I pull in that area.

 

Is this true. So anything 27+ should be set to 27? I read in the "mivec tuning" the limit was 28. Can anyone confirm this along with the effects.

 

Not at all...I'm just reporting what I have experienced on my own car. Many others are using 28 just fine. I'm sure only having access to 91oct is the main reason I cant crank it up so far.

 

well im currently on stock map with 93 octane. I'm about to reflash my car though because its getting horrible gas mileage with the parts I have on and I feel like I should be optimizing the power anyway. Not going to increase boost just yet until the fuel pump goes on but I need to re-tune it.

I was going to set Mivec to 24* in the mid region. but I may just go with trial see how it reacts.

 

ya my car seems more knock prone with to much uptop 200-240 load/ 6000RPM.
I can give it full 28.8 for spool with no problems.
Im also playing with it in determination of effects on lift off knock. My thinking is while the you lift off the throttle no more air is really entering the engine, to much mivec can cause exhaust air to enter the intake valves causing knock.
the whole purpose of valve overlap is to help the incoming air to push the exhuast out. But if you get no air then lots of valve overlap is pointless.

 

^^^ this is exactly what I was thinking. I was only going to tune aggressive mivec for 2500-4500 range just to help spool then let timing take over for the rest of the way up. Mivec for the IX was only developed to help spool not top end. If we had an exhaust mivec cam then that'd be a whole nother story, but I think 2500-4500 would aid in spool seeing as more compressed air is usually pushed in @ 3600-5k then boost begins to taper.

 

I have the cossie M3s and too much Mivec during spoolup causes knocks.