Timing Help

[jmsmotorsport]

Am currently tuning a VX SS M6 with a 227/241 109LSA .563lift cam. Now i have got the idle nice with the RAFIG process was surprisingly easy. VE is is close with some small lean spots part throttle low in the rpm range, so I have moved onto correcting the timing. While out logging I could feel flat spots around the 3500-4000rpm range, while watching the PC I noticed timing being pulled right down to 13 and at one stage 9 this is only for a MS but you feel it as its going from 25 to 9 then back up, Not recording any KR at these points but sometimes after when it jumps back up, i will attach a log, it does show KR and I am working through the timing table to remove this. Im just curious as to what would be pulling so much timing?

1935119350

[jmsmotorsport]

Am currently tuning a VX SS M6 with a 227/241 109LSA .563lift cam. Now i have got the idle nice with the RAFIG process was surprisingly easy. VE is is close with some small lean spots part throttle low in the rpm range, so I have moved onto correcting the timing. While out logging I could feel flat spots around the 3500-4000rpm range, while watching the PC I noticed timing being pulled right down to 13 and at one stage 9 this is only for a MS but you feel it as its going from 25 to 9 then back up, Not recording any KR at these points but sometimes after when it jumps back up, i will attach a log, it does show KR and I am working through the timing table to remove this. Im just curious as to what would be pulling so much timing?

1935119350


Well after searching though tables i found the Burst knock table zeroed this and now its happy as.

[joecar]

Well after searching though tables i found the Burst knock table zeroed this and now its happy as.Good deal :cheers:

post new logs.

[jmsmotorsport]

Good deal :cheers:

post new logs.

19354

[joecar]

19354
I see some KR, looks like real knock... it looks like the same thing as the previous log (which had much more).

[joecar]

Am currently tuning a VX SS M6 with a 227/241 109LSA .563lift cam. Now i have got the idle nice with the RAFIG process was surprisingly easy. VE is is close with some small lean spots part throttle low in the rpm range, so I have moved onto correcting the timing. While out logging I could feel flat spots around the 3500-4000rpm range, while watching the PC I noticed timing being pulled right down to 13 and at one stage 9 this is only for a MS but you feel it as its going from 25 to 9 then back up, Not recording any KR at these points but sometimes after when it jumps back up, i will attach a log, it does show KR and I am working through the timing table to remove this. Im just curious as to what would be pulling so much timing?

1935119350


Well after searching though tables i found the Burst knock table zeroed this and now its happy as.Burst knock is typically seen on throttle increase...

your log shows KR in the middle of steady large throttle, and seems to be the at 4000 rpm...

[jmsmotorsport]

Yeah I have also seen that and am working through reducing timing to remove. There was also some knock from part throttle to WOT but at that moment AFR leaned dramatically. If you look at the other log the burst knock issue wasn't actual knock but the burst knock parameters killing timing. I could probably leave the burst knock timing and increase the airflow change amounts to stop burst knock activating.

[jmsmotorsport]

Well turns out that last log that still shows some knock had some lean spikes around the points this was occurring, seemed odd as log before afr's looked pretty tidy, turns the alternator died while logging and I gather this caused injector a fuel pump voltage fluctuations making my AFR untidy and contributing to the knock as wot timing at these points is 19-21degrees

[joecar]

Too bad for the alternator.

[joecar]

Yeah I have also seen that and am working through reducing timing to remove. There was also some knock from part throttle to WOT but at that moment AFR leaned dramatically. If you look at the other log the burst knock issue wasn't actual knock but the burst knock parameters killing timing. I could probably leave the burst knock timing and increase the airflow change amounts to stop burst knock activating.This is a good idea, increase the airflow delta to just barely above the current BKR trigger point (to avoid BKR now, but too allow for those cases where the load is really too much).