E38 with boost not holding timing steady

[9secVette]

Hi guys,
Just wondering if anyone has seen this, I have both timing tables the same, no knock (or minimal knock) and the timing jumps around under boost. Sometimes 5-7 degrees which is enough to feel it in the car.

I have gone threw every table imaginable in the spark area, yet timing will drop. I will have it set at say 12 degrees and sometimes I might see it go as low as 5-7 degrees without knock or high IAT's.

Any suggestions?

Thanks in advance.

[Redline Motorsports]

It might be better to post a log file. How much boost and how deep are you into the MAF table?

Howard

[Highlander]

this is speed density right?

[9secVette]

Thanks for the replies guys.

This is with about 8-9 lbs of boost in SD. I found that with the new style MAFs they are too sensitive to the BOV flutter and caused funky readings so I just shut it off and it's much smoother.

I will get a copy of my file up shortly (at work now)

[oztracktuning]

Get rid of burst knock and see what happens.

[9secVette]

I found the problem cleared when I brought the low and high timing tables closer together. I left the low table stock and from minor knock (1-2*) it would bring it into the low table which was much lower then the high, which would drop timing a fair amount.

Thanks for the replies.

[Highlander]

The problem I had was that it was actually oscillating... Not sure if it was your problem...

[oztracktuning]

Turn off burst knock, that IS the cause. Ive seen it happen heaps of times with boosted E38s

[9secVette]

Turn off burst knock, that IS the cause. Ive seen it happen heaps of times with boosted E38s

Thank you very much, it seems to be taken care of with the timing table adjustment, but I will take your advise as well.

[Highlander]

Turning off burst knock didn't help on this one. I reverted back to the MAFd tune to cure this.