Surge
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12 Second Club
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Joined: Apr 2004
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From: Grand Rapids, Michigan
Surge i've been messing with my tune ever since installing my cam/underdrive/TB. i have it running really nice now and idling perfectly. i did get a lot of surging under light throttle under 1,500 rpm. i fine tuned the idle timing, run timing, VE and throttle cracker tables but it was still there. one thing i noticed was it only happened when i was barely giving it gas. pretty much any throttle or load made it go away. i reduced my idle % enable from 1.4% to 1% and that made it much better. that made it practically all go away but there's still a little bit every so often. is there an amount i'm going to have to learn to live with (ie, keep the rpm up) or is it possible to completely tune it out? cam is 228/232 .611/.600 111 lsa, BBK 80mm TB
I Believe U Are Gonna Just Have To Get Used To A Small Amount Of Surge...out Of All The Cammed Cars I Know Of Here In Town They All Surge At Least A Lil When U Are Under That 1500rpm Range
What I've done so far to get rid of my surge was add a little fuel and timing. Its much better. Now it only feels like a hesitation rather than the bucking I was getting earlier. I'm going to try to add more of both to see if it eliminates it altogether.
I haven't found an easy way to identify the culprit, but most of the cause of surging I've found to be:
fuel
spark
throttle cracker
And not necessarily in that order, and most of the times all of the above.
fuel
spark
throttle cracker
And not necessarily in that order, and most of the times all of the above.
Thread Starter
12 Second Club
iTrader: (3)
Joined: Apr 2004
Posts: 1,512
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From: Grand Rapids, Michigan
Originally Posted by YellowToy/A
Add a little air in the follower table. Just at the low throttle settings.
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I have a similar cam that I'm trying to dial in also. Same exact symptoms, idle is mint, follower and cracker don't seem to help but just off idle to 1500 rpm there is a slight bucking/surging. The log shows no significant spark variances (no more than a degree) so that's not the issue, I'll try lowering the idle % and see if that helps. I have this darn close I can't wait to get it perfect!
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If this is present only in closed loop then look at
the delivered, high resolution pulse width and the
RPM and see if the pulse width looks like RPM surge
but leads it any. See if the NBO2 voltage swing is
in sync with the RPM surge, If so this may be the
proportional fuel swing messing you around.
Proportional fuel amount can be scaled down by the
same factor you scaled up the injector size, or more.
If the NBO2s are pegging then you have more
proportional fuel than you need to get cross-counts.
the delivered, high resolution pulse width and the
RPM and see if the pulse width looks like RPM surge
but leads it any. See if the NBO2 voltage swing is
in sync with the RPM surge, If so this may be the
proportional fuel swing messing you around.
Proportional fuel amount can be scaled down by the
same factor you scaled up the injector size, or more.
If the NBO2s are pegging then you have more
proportional fuel than you need to get cross-counts.
