I thought I'd post an observation because it threw me for a loop. The Idle Underspeed Adders will only add spark up to the value in the High Octane (maybe Low?) Tables. I was working on getting the perfect lope at 700rpm and getting the throttle kracker to function properly with my extensively ported throttle body when I found the issue. A search didn't turn up anything, so I figured I'd put this out there for anyone else scratching their head.
2007 Grand Prix GXP, Modded CAI Intake, 85mm MAF, LS6 Intake Manifold, 42# LS3 Injectors, New Era G8GT High-Lift DOD Cam (Modded Timing Gear, 20* Advanced from As-Ground), PAC 1218 Springs, Trickflow 7.45" Pushrods, Doug Thorley Headers (w/Custom Crossover Pipe), Cutout and Maxflows, TEP Transmission (Hardened Input Shaft, 3.29s), HP Tuned by Me, Pioneer Speakers and MTX Subs, 13.1 @ 108.5 on street tires at full weight.
Good find, be interested to hear if others have found this also??
Cheers
Benno
what pcm? post tune..
Would like to know the same. Probably is an issue of too much idle air. Get the idle air dialed down, and it will add timing to maintain idle speed.Originally Posted by carlrx7
EFI specialist
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It's an E67 in an '07 GP GXP. I'll try to post my tune tonight, although it will be my latest and possibly in another thread with an open invitation for criticism. The issue resulted from me matching my High Octane tables to my Idle tables in the idle region trying to see how that would effect my launch feel. It may have been a little smoother, but then I would only see overspeed spark reduction and not underspeed spark increases. If I scanned the idle adaptive spark pid, I would see positive numbers without any corresponding increase in advance. I didn't realize that there would be any interaction between the two spark tables outside of there being a fixed slew rate used to transition between them. I bumped my High Octane tables back up into the 30s, and I immediately started to see underspeed correction again.
2007 Grand Prix GXP, Modded CAI Intake, 85mm MAF, LS6 Intake Manifold, 42# LS3 Injectors, New Era G8GT High-Lift DOD Cam (Modded Timing Gear, 20* Advanced from As-Ground), PAC 1218 Springs, Trickflow 7.45" Pushrods, Doug Thorley Headers (w/Custom Crossover Pipe), Cutout and Maxflows, TEP Transmission (Hardened Input Shaft, 3.29s), HP Tuned by Me, Pioneer Speakers and MTX Subs, 13.1 @ 108.5 on street tires at full weight.
I have noticed the same, in my E38, 12619078 OS, the overspeed commands +16 (on top of 20 base idle spark) but the actual wont exceed my high octane table limit of 30.
2010 GXP Maloo ute, LS3, 6L80E.
MM heads, 240/252@50 solid cam, 12.75:1 compression, 4500 Dominator converter, 3.46 rears.
Shooting for 10s eventually.
there is no such limit, please email your file to support, it sounds like there may be a bug with the idle spark PID in the scanner.
Chris...
I count sheep in hex...
I found the same thing to be true on my E40 tune Chris. I've set the idle timing to match HO timing and it will not add timing beyond that number when the idle RPM drops below desired RPM. I have the minimum RPM set 100 below target as well. It will, however, drop timing if the RPM goes over target. Should I send the tune and log file to you as well?
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