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Old 05-12-2000, 12:30 PM   #1
Tim Prudence
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Question Deceleration function on the S-AFC, anybody know how to setup?

It says in the manual that this is used to correct for BOV venting to atmosphere on Hot Wire equipped cars. But I don't understand what they are trying to say with how to configure it. I tried once, and my car just stalled, wouldn't idle at all. Has anyone got this function working?
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Old 05-12-2000, 02:01 PM   #2
MPREZYA
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Tim in your other post you mentioned that the ecu sees a rich condition when you shift and it leans it out shouldn't that tell you that you should run it <0 on the deceleration function? It sounds like that would clear your problem of the ECU correcting for the rich condition due to the BOV purging.
Rich
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Old 05-12-2000, 03:26 PM   #3
Tim Prudence
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Yeah, it seems pretty simple but things you plug into the setting are throttle position, and ne1 and ne2. All three of these are positive percentages (ne1 and 2 have one decimal place so they're probably meant to be small). I just don't get what it all means...

I understand the throttle setting, if throttle is below this point, then the decel function should take effect. I'm guessing that ne1 and ne2 are MAF % that will be outputted overiding what is actually being read.
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Old 05-12-2000, 03:37 PM   #4
SteveS
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Quote:
I'm guessing that ne1 and ne2 are MAF % that will be outputted overiding what is actually being read.
This is what is confusing to me when I read the "instructions" (which is really stretching it). ne1 and ne2 are actually just the first 2 set points for fuel correction. ne1 and ne2 really are the representations for the actual RPM reading that you've configured (for those 2 points). KWIM?

So, the throttle setting is the minimum threshold before the decel function kicks in? Does the decel function kick in EVERY time the throttle drops below this setting? That doesn't make much sense to me, either, since it would be in effect at idle. Again, KWIM?

And the instructions refer to control threshold, or something similar, but it's a poor translation at best.
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Old 05-12-2000, 05:49 PM   #5
Tim Prudence
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Quote:
So, the throttle setting is the minimum threshold before the decel function kicks in? Does the decel function kick in EVERY time the throttle drops below this setting?
I'm not really sure. It says to set some values higher than at cold idle and some lower...

Those "instructions" are garbage, it would be nice if they just tried to explain what the function is doing instead of giving a formula for setting and forgetting, because it makes it difficult to troubleshoot.

I'm going to speak with my Apex'i dealer this weekend.
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Old 05-13-2000, 01:01 AM   #6
SteveS
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Tim ~~ I'm having the same frustration. I like to think that my reading comprehension level is pretty good, but I'm completely missing the point on how to set the decel function properly. My car DOES stall if I wind it out in 1st or 2nd and then push in the clutch and let it coast. Power steering without the power is worse than manual, let me tell you!

I'm about to the point where I'm thinking about contacting Apex'i USA to see if they can provide a better explanation.

FWIW, I have messed around with having the "corrections" > 0 and haven't seen ANY difference. I've wondered if I shouldn't try setting the correction to < 0, but I haven't tried it yet.

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Old 05-15-2000, 05:52 AM   #7
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Tim ~~ I messed around with this a little more this weekend (after my car almost stalled twice when stopped on a steep incline at a stop sign). I ran a couple of WOT tests in both 1st and 2nd gear where I took it up to redline and then just pushed in the clutch. I have it set where it doesn't stall now. In 1st the car gets very close to stalling, but recovers. In 2nd the car never really gets close to stalling, staying above 1K rpm.

Here's my settings, FWIW:
Thr: 5.5%
Ne1: 11.5%
Ne2: 13.5%

Hopefully you'll be able to find a better method than what I did. I tried setting the Throttle setting higher, but then I was having some issues with drivability. When cruising, if I backed off the gas even slightly, the car would "engine-brake". Really drastic feeling, too, almost like I had an automatic and the car couldn't quite find a gear it was happy with. So I backed out of the Thr setting...
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Old 05-15-2000, 10:53 AM   #8
Tim Prudence
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Hmm...

Those settings are a bit higher than the ones I came up with. My ne1 is at 1000 and my ne2 is at 2000. What worked well for me was:

thr - 3%
ne1 - 2.5%
ne2 - 3.5%

Or something like that...
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Old 05-15-2000, 02:12 PM   #9
SteveS
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I'll give these settings a try. FWIW, I have moved my Ne1 and 2 settings up to 3K and 3.5K respectively since I wasn't doing any tuning at below those points.
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Old 05-15-2000, 02:43 PM   #10
Tim Prudence
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Then your numbers are probably right. If your ne points are higher than mine, then the airflow percentages at those points will need to be higher as well.
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Old 05-18-2000, 06:37 AM   #11
SKiDaZZLe
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Lightbulb

Tim and steve,

i am currently running 8lbs on the legacy turbo kit i put on my 99 RS (will go to 10 when the BEGI RRFPR comes in). i have my greddy type S BOV vented to the atmosphere, and do NOT have an Apex AFC. I have the feild unit, which does not have decel function.

anyway, the car has never stalled when i engage the clutch, and coast to a stop. now, what it DOES do is almost die (like drop to 400rpm) then back up to 1000rpm, then back down to 700rpm. It will do this if i am either coasting to a stop, or even gunning it in neutral.

my point?
maybe you guys need to tighten or loosen the BOV some more. currently, i can feel a little vacuum created at the outlet, at idle. i remember someone posting that the BOV should not be leaking air (i dont know if they said in or out) at idle. mine does it slightly in. it has not had any problems, yet.

i think it might be a problem at 10-12psi, since on decel, there will be alot more air "missing" in the throttle body. this will just make me buy an AFC (if you guys can get it working correclty! )

michael


[This message has been edited by SKiDaZZLe (edited May 18, 2000).]
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Old 05-18-2000, 10:40 AM   #12
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When you close the throttle after running fast, the blow-off valve allows the extra air to go-away. This allows the turbo to continue to spool, so the MAF is still reading a lot of airflow. The ECU sees this and continues to dump fuel into an engine that is not seeing much airflow. This leads to a very overrich situation which helps stall. The override allows the add-on computer to detect where the throttle is via the TPS sensor, and when it 'sees' enough deceleration of the throttle is overrides the MAF to send a lower flow rate to the injectors.

<< anyway, the car has never stalled when i engage the clutch, and coast to a stop. now, what it DOES do is almost die (like drop to 400rpm) then back up to 1000rpm, then back down to 700rpm. It will do this if i am either coasting to a stop, or even gunning it in neutral.>>

As the car begins to die (too rich), the idle air control solenoid opens up- same effect as you opening the throttle. This causes the idle to surge up. ECU sees RPM too high, closes solenoid more. Finally situation is corrected.

I don't have your AVC, but if I had programmed a 'generic' decel function, I would need to know the percent throttle closing difference at which the function should take place, and perhaps an RPM drop as well. Then I would want to know when to turn it off. I would imagine your settings are expressing some combination of these settings. So, if you let x% off the throttle and rpms dropped by x% what % of airflow reading should be taken away?

Does this help at all?

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