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View Full Version : E38 with boost not holding timing steady


9secVette
December 9th, 2008, 05:18 AM
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.:cheers:
Redline Motorsports
December 9th, 2008, 10:02 AM
It might be better to post a log file. How much boost and how deep are you into the MAF table?

Howard
Highlander
December 9th, 2008, 01:04 PM
this is speed density right?
9secVette
December 15th, 2008, 02:20 PM
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) :cheers:
oztracktuning
December 25th, 2008, 01:27 AM
Get rid of burst knock and see what happens. :)
9secVette
March 8th, 2009, 05:18 AM
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. :cheers:
Highlander
March 8th, 2009, 05:21 AM
The problem I had was that it was actually oscillating... Not sure if it was your problem...
oztracktuning
March 8th, 2009, 07:52 PM
Turn off burst knock, that IS the cause. Ive seen it happen heaps of times with boosted E38s
9secVette
March 17th, 2009, 07:10 AM
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. :cheers:
Highlander
June 5th, 2009, 05:52 PM
Turning off burst knock didn't help on this one. I reverted back to the MAFd tune to cure this.
oztracktuning
June 5th, 2009, 06:10 PM
A MAF tune can only support with accuracy in fueling on transition up to around 5-6 psi of boost. We now do most of our E38 boosted cars in open loop 2 bar and get very smooth power at all levels of boost. Especially on transition into boost.
9secVette
June 18th, 2009, 09:58 AM
A MAF tune can only support with accuracy in fueling on transition up to around 5-6 psi of boost. We now do most of our E38 boosted cars in open loop 2 bar and get very smooth power at all levels of boost. Especially on transition into boost.



I do the same, but leave them in closed loop for fuel economy.:)