idle mode
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Re: idle mode
Originally posted by 11sORbust
Could somebody shed some light on this parameter. I have the idle mode flag checked under wot but the idle spark gets disabled....
Could somebody shed some light on this parameter. I have the idle mode flag checked under wot but the idle spark gets disabled....
Now for the idle SA control there is another TPS% threshold that is used. It is an IAC idle control threshold which is used for IAC and SA idle control.
RBob.
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Originally posted by 11sORbust
I had it reversed The idle spark is the one staying on..
I had it reversed The idle spark is the one staying on..
There isn't any status bits that define whether the idle SA is active or not. The only idle SA status that is output via the ALDL is the one above (as long as I didn't miss any).
RBob.
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Car: 91 GTA, 91 Formula, 89 TTA
Engine: all 225+ RWHP
Transmission: all OD
Axle/Gears: Always the good ones
go thru the anht hac and check thru the spark tables :-)
Can retard 5 degree and add 5 degree at idle :-)
Believe Rbob was saying that the idle dropped(rpm) or changed and the ecm added timing too compensate to correct it back to your settings
later
Jeremy
Can retard 5 degree and add 5 degree at idle :-)
Believe Rbob was saying that the idle dropped(rpm) or changed and the ecm added timing too compensate to correct it back to your settings
later
Jeremy
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The thing is that my rpm at idle is not rock steady(because of the HUGE cam). Guess the ecm looks at that as an rpm error and corrects spark. Seems to be THE reason my timing jumps around at idle. I modified the main spark table to get a steady reading through aldl(for timing). It helped but you are saying it's correcting sa and using the idle speed error table,yes? If so then I just need to zero out those two tables. It's all related to the monster cam. When I'm done tuning for this cam I'll post what I learned.
The idle error thing would seem to effect most large cammed engines....
The idle error thing would seem to effect most large cammed engines....
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Originally posted by 11sORbust
The thing is that my rpm at idle is not rock steady(because of the HUGE cam). Guess the ecm looks at that as an rpm error and corrects spark. Seems to be THE reason my timing jumps around at idle. I modified the main spark table to get a steady reading through aldl(for timing). It helped but you are saying it's correcting sa and using the idle speed error table,yes? If so then I just need to zero out those two tables. It's all related to the monster cam. When I'm done tuning for this cam I'll post what I learned.
The idle error thing would seem to effect most large cammed engines....
The thing is that my rpm at idle is not rock steady(because of the HUGE cam). Guess the ecm looks at that as an rpm error and corrects spark. Seems to be THE reason my timing jumps around at idle. I modified the main spark table to get a steady reading through aldl(for timing). It helped but you are saying it's correcting sa and using the idle speed error table,yes? If so then I just need to zero out those two tables. It's all related to the monster cam. When I'm done tuning for this cam I'll post what I learned.
The idle error thing would seem to effect most large cammed engines....
I've found that a _little_ idle SA correction helps. I also tweaked in the idle SA correction MAP multiplier tables. One problem here is the range of the MAP mult tables may not cover the idle area of a hi-po engine.
It can take some staring at log files to see where to move things. Then of course trying it out.
RBob.
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Here is a snapshot of my 406. You can see the spikes in timing. On every spike the idle spark bit displayed is "1". I will change the idle speed error tables and post the results. My bet is a rock solid idle s/a.
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There use to be more s/a spikes and dips when I first started to tune. The main reason s/a varied was the map signal. I re-routed some vac lines and the signal improved. Then I had to go into the area (in main spark table) where my engine idles. Since the rpm varied I change the spark like this..
( I know the table as a whole is a mess. I'm waiting for the 3500rpm converter before brushing things up)
( I know the table as a whole is a mess. I'm waiting for the 3500rpm converter before brushing things up)
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Originally posted by 11sORbust
comments are welcome
comments are welcome
Nice graph. I'd say that the engine has the typical rolling idle. It may even be getting pushed a bit by the idle SA correction values. Can see this in the MAP value. The RPM changes are too hard to see in this particular graph.
Looking at the SA and the MAP notice how as the MAP increases (falling RPM) the SA also increases. Maybe too much as the MAP will quickly decrease (rising RPM). The ECM then responds by decreasing the idle SA and the RPMs drop back down.
I'd start out by zeroing the idle SA correction tables (just the SA ones, leave the MAP compensation tables at 255).
Then data log the idle. If it is rolling add a little SA to the too-low idle speed table. Data log again, and see if it helped.
May also need to pull a little SA from the too-high SA idle speed table too. A little at a time until the rolling subsides.
Make sure there is enough dead zone so that the idle SA correction isn't fighting.
RBob.
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Car: American Iron Firebird
Engine: The little 305 that could.
Transmission: Richmond T-10
Axle/Gears: Floater 9" - 3.64 gears
Would adjusting the idle deadband help in a situation like this?
I haven't had to tune a lumpy cam motor yet but I would think it would help from over correcting.
I haven't had to tune a lumpy cam motor yet but I would think it would help from over correcting.
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FYI, the cam specs are 242/250*duration,.540/570"lift,114*lsa
The idle is good. It only changes 50rpms. It's just those darn timing spikes. I'll post the results tomorrow.
The idle is good. It only changes 50rpms. It's just those darn timing spikes. I'll post the results tomorrow.
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Car: American Iron Firebird
Engine: The little 305 that could.
Transmission: Richmond T-10
Axle/Gears: Floater 9" - 3.64 gears
Originally posted by 11sORbust
FYI, the cam specs are 242/250*duration,.540/570"lift,114*lsa
The idle is good. It only changes 50rpms.
FYI, the cam specs are 242/250*duration,.540/570"lift,114*lsa
The idle is good. It only changes 50rpms.
Hopefully my logic isn't too crappy, but I'm still learning. I even picked up a '90 Formula to keep learning on... well, after I fix the intake leaks and rust
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Car: An Ol Buick
Engine: Vsick
Transmission: Janis Tranny Yank Converter
Yep, with what RBob said.
Is your IAC moving around while this is going on?.
The idle deadband sets how close the ecm tries to keep the actual idle speed to the commanded.
I typcially set the first couple of idle spark corrrection entries to 0. And then no more then 4d after that.
If you load up RBob's new 58 ecu file and look at a 58 bin you can see the IAC deadband settings. I just mention his since I was just looking at it. Others probably have it...
Is your IAC moving around while this is going on?.
The idle deadband sets how close the ecm tries to keep the actual idle speed to the commanded.
I typcially set the first couple of idle spark corrrection entries to 0. And then no more then 4d after that.
If you load up RBob's new 58 ecu file and look at a 58 bin you can see the IAC deadband settings. I just mention his since I was just looking at it. Others probably have it...
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Is your IAC moving around while this is going on
Last edited by 11sORbust; 05-08-2004 at 09:20 AM.
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Ahhh, ok. I was wondering if the idle was flucuating too much and causing the KPa to change which made the SA spike.
There use to be more s/a spikes and dips when I first started to tune. The main reason s/a varied was the map signal. I re-routed some vac lines and the signal improved. Then I had to go into the area (in main spark table) where my engine idles. Since the rpm(edit: I mean MAP not rpm) varied I change the spark like this..
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Originally posted by 11sORbust
Anyone want to look at my bin and help find the .4* idle (s/a)correction? I don't see how there is still correction...
Anyone want to look at my bin and help find the .4* idle (s/a)correction? I don't see how there is still correction...
The idle does look much better. The IAC is doing a little work too. May be able to reduce that by getting a little timing correction back in.
RBob.
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