Idle spark

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Idle spark

Unread postby 351pwrdstang » Mon Dec 12, 2016 7:16 pm

Here's a dumb question but where does the ecu get the spark value for idle. I noticed tonight my idle had a slight surge 1000 to 900. Not too unruly but it wasn't there before. I was actually logging iat with new cooler and caught it before I shut her down. CT spark is 34 with adder and that's where it always stays at idle but during the surge spark is dropping to 22. With a 100 rpm variation load is consistent and nowhere in the spark tables is close to 22. Everything is pretty flat minus the spark dropping out.
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Re: Idle spark

Unread postby SlowBox » Mon Dec 12, 2016 7:49 pm

FN111
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Re: Idle spark

Unread postby Shaker666 » Fri Jan 13, 2017 9:55 am

Since tuning on EEC-V CDAN4 for a couple of years, I've been spoiled with feedback spark parameters to control idle with spark. Of course the concept of feedback spark hadn't been quite formalized in EEC-IV, but it sure looks like FN841D and FN841N are precursors to what would eventually become a PID control in EEC-V. Anyone with me on that?
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Re: Idle spark

Unread postby decipha » Fri Jan 13, 2017 2:08 pm

why do you have 34 degrees at idle? I wouldnt shoot her anymore than 26 at the absolute most unless you have some really inefficient slow burn heads

if your using the a9l2 (sounds like you srent with all that spark) then the idle spark feedback is coming from the idle spark multipliers, if using another bin then all the idle spark multipliers come in to play, the fox timing write up on the homepage gives you all the details

err correction, its not there! I'll add it in when i get a chance.
Anywho,

22/34 = 0.65

that would mean idle is hella above NUBASE and the multiplier is yanking out a ton of spark to reach idle

theres also an ECT modifier, Dashpot modifier, BP and if im not mistaken another modifier on idle spark as well.

And for reference when i get around to adding it
http://efidynotuning.com/foxtiming.htm
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Re: Idle spark

Unread postby 351pwrdstang » Fri Jan 13, 2017 5:42 pm

Its an sct tune done by local shop years ago. Closed throttle spark was 31 with a 3 degree adder. I jacked on the idle screw some and she went right into idle spark control moving around. Also cleaned up the surge. This is same car that rattled between wot shifts. Go figure.
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Re: Idle spark

Unread postby decipha » Fri Jan 13, 2017 6:31 pm

its time to throw that sct tune in the dump and really dial her in
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Re: Idle spark

Unread postby Shaker666 » Fri Jan 13, 2017 7:03 pm

Yep, I just had a guy with a '65 Daytona Coupe have to yank an Anderson PMS system clear out of the car. Also had to remove an MSD BTM unit. Dialed it in using QH and burned him an F3 chip, runs properly for a change now.
'89 supercharged 8.6:1 5.0 Mustang: EEC-IV (GUFB:A9L) with EDIS8
'79 Bronco: 8.5:1 408M EEC-IV (GUFB:X3Z) with EDIS8
'71 Mach 1: RIP
'66 Mustang GT: needs EFI
'00 Mountaineer: 9.15:1 302W EEC-V, EDIS, 4R70W stock
'08 Buell: 10:1 DDFI-3
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Posts: 412
Joined: Thu Oct 17, 2013 10:23 pm
Location: Tucson, AZ
Name: Manu "Shaker" Singh
Vehicle Information: '89 Mustang 5.0 LX Sport: blown 8.6:1 306 EEC-IV+EDIS8. Ported Vic Jr. heads, LMAF, Accufab 90mm TB, KB 2.2 Blowzilla w/Flowzilla, Deka 80s, AEM dual nozzle water injection, shorty stainless headers into 2.5" X-pipe, dual O2. A9L2 QH tuned.
Vehicle 2 Information: '79 Bronco Ranger XLT: 8.5:1 400 EEC-IV+EDIS8 ignition. Stock heads, LMAF, Ford 65mm TB, Cobra upper, 351W GT40 lower, Ford 24s. Full length headers with 1.75" primaries into 3" Y-pipe, single O2. TwEECed A9L.
Vehicle 3 Information: '71 Mustang Mach 1: Totalled
Additional Vehicles: '08 Buell XB12Ss Lightning: factory 10:1 motor with DDFI-3 control. Drummer exhaust, dual O2 mod, baro mod. DDFI-3 tuned via TunerPro RT.
'07 Mazda 3S: mainly stock, minor suspension and chassis reinforcements.
'00 Mountaineer: 9.15:1 302W EEC-V, integral EDIS8. Stock with exception of 1" TFS intake spacer, cold air intake, and Magnaflow exhaust.


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