Specific CL tweaks when overrun-to-idle situation

Give input on tuning as well as any tips and tricks you may have. Also feel free to share base mapping files for various engine types.
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86sixsix
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Re: Specific CL tweaks when overrun-to-idle situation

Post by 86sixsix »

VR6Turbo wrote:unembarrassing time
:lol: i'd be surprised if it stalled anyways :lol:
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FrankCorrado
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Re: Specific CL tweaks when overrun-to-idle situation

Post by FrankCorrado »

Yeah but what if I use a smaller number, 60-70 and I cut ISV above 1500rpm. Then ISV kicks in at 1500 only, pushing 50-60-70 and PID will pull it down. May not be a conventional way of doing things but if it prevents from stalling, for a certain time I could live with it until I get things right.

I never dip the clutch at 1000rpm, I never engage a gear under 1500rpm, except when launching in first, but I'll be in accel over the TPS for control so the ISV will be shut.

But having same numbers in all rows is the same as filling in up with 80s everywhere. :) I will just fill it up with another number. Or you mean each row should have the same number for each temp? Like at 1500rpm from 0C to 120C same number, but at 1000rpm it could be a different number as long it's the same from 0C to 120C?
Frank
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MarcoV6T
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Re: Specific CL tweaks when overrun-to-idle situation

Post by MarcoV6T »

Hi Frank,
A few suggestions, if your CL is pulling 15% fuel, then you need to trim your map first, and let it adjust 10-5% max.

To start with, I wouldn’t use the overrun function, it works better if you do it in your map using short injection times(which you already do), enable it later eventually. The problem with ORFC, is that it can dry the runners which leads to hiccups.

The thing I would change in your fuel map is this; in the 'overrun' column(20kPa) at 1000rpm, put the same number as the 30kPa row, then from the 1000rpm cell interpolate the fuel numbers to the 1750rpm cell, this will wetten your runners before it returns to the idle cell's. I would also add more fuel at your 400rpm row for two reasons, first the engine will run stronger when the rpm’s are dropping, second, when the engine speed goes below 600-700 rpm, the air speed is a lot slower and the fuel drops out of the air flow(the air/fuel mix gets worse), and thus you need to add more fuel.

Also, your fueling numbers look a little weird, you have a big drop at 3250-4000rpm, doesn’t seem right to me, it should go up from 1500~5000rpm, even if you have a little torque drop in that region, you’re better to keep the numbers flat, and let CL handle it if you’re cruising in that region.

Regarding the ignition timing at idle, I would not go higher than around 12° at 750-1000rpm and add more fuel if needed, but bump it up a little in the 400 rpm row to keep it from stalling, to say 15-16°. Again in the ‘overrun’ column, drop the timing to around 15-12°, starting from 2000rpm, this will result in a more fluid return to idle.

The thing is to change only one parameter at a time(fueling, advance, etc) and do it with CL turned off, otherwise you’ll end up chasing your tail.

@Kevin, I’m sorry I did not respond to your latest email, but unfortunately Murphy’s law did strike again, but I’ll catch up later.
FrankCorrado
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Re: Specific CL tweaks when overrun-to-idle situation

Post by FrankCorrado »

Yes my fuel is not complete yet, but in the 1500 less region it is. Since it's not complete this is why I stlil use Remove 15%. I still have situations where removing over 10% ends up in the right Target AFR. But I think I will get your box and go either on the road or dyno, turn those knobs and hit the save button. That should help me tune the fuel a lot faster. I will PM you.

So you think it's better to not use the CL overrun settings? Except the one that says Shut off fuel when TPS under x%, I believe.

You think 18-20 timing on 8.5CR and short runner manifold may be too high under 750rpm?

Yes all these ideas and Rick's ISV MAP are all interesting, I will prepare my map for my next changes and see how that old VR behaves. :)


Tnx!
Frank
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VR6Turbo
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Re: Specific CL tweaks when overrun-to-idle situation

Post by VR6Turbo »

MarcoV6T wrote:@Kevin, I’m sorry I did not respond to your latest email, but unfortunately Murphy’s law did strike again, but I’ll catch up later.
No worries Marco. I figured you may be busy 8-)
I do have my R32 engine running OK but I would like to check a few things with you.
FrankCorrado
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Re: Specific CL tweaks when overrun-to-idle situation

Post by FrankCorrado »

Kev discard my email concerning the box, I got my answers. :)
Frank
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FrankCorrado
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Re: Specific CL tweaks when overrun-to-idle situation

Post by FrankCorrado »

MarcoV6T wrote:To start with, I wouldn’t use the overrun function, it works better if you do it in your map using short injection times(which you already do), enable it later eventually. The problem with ORFC, is that it can dry the runners which leads to hiccups.
But doing so the CL will be turned on when I come out of overrun, therefore defeating Rick's idea saying something like "when the engine comes out of overrun it takes a certain time to stabilize, if CL tries to correct fuel during that time it will yield to messy fuel changes and AFRs. This -time- is engine specific."

MarcoV6T wrote:The thing I would change in your fuel map is this; in the 'overrun' column(20kPa) at 1000rpm, put the same number as the 30kPa row, then from the 1000rpm cell interpolate the fuel numbers to the 1750rpm cell, this will wetten your runners before it returns to the idle cell's. I would also add more fuel at your 400rpm row for two reasons, first the engine will run stronger when the rpm’s are dropping, second, when the engine speed goes below 600-700 rpm, the air speed is a lot slower and the fuel drops out of the air flow(the air/fuel mix gets worse), and thus you need to add more fuel.
Yeah that sounds pretty good. I've up 15% the 400 row and moded the 20-30 columns, Like this:

Image

MarcoV6T wrote:Regarding the ignition timing at idle, I would not go higher than around 12° at 750-1000rpm and add more fuel if needed, but bump it up a little in the 400 rpm row to keep it from stalling, to say 15-16°. Again in the ‘overrun’ column, drop the timing to around 15-12°, starting from 2000rpm, this will result in a more fluid return to idle.
Fuel is done, will test it next Spring. Then will test the timing, which will look like this:

Image


I use MAP as LOAD and no temp compensation when engine is at normal operating temps, which means the numbers you see there are the real TOTAL timing (and fueling, above).

tnx for the tips!
Frank
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