richardjh

Hi Bryan.

Those are still stock...




My real problem area for sudden WOT spool-up is 4000-4500rpm. Those are open-loop quite early, from the looks of it.

Note: I have bog-all experience with these. Never played with 'em.




I've been mulling over all this stuff overnight. I've always had trouble coping with the apparent discrepancy between AFR readings when passing through a "cell" vertically (ie. increasing rpm, steady load) and passing through it horizontally (ie. steady rpm, increasing load).

For mid-map cells, it means I see very different mixtures spooling up at 4000 rpm though 160 load compared to accelerating part-throttle at 160 load.

Tephra's "sudden knock" thread touches on a lag between target MIVEC exhaust valve control and the actual logged behaviour at spool-up. This sounds like it would explain the discrepancy very neatly: Aggressive MIVEC skews fuelling at spool-up.

I can tune with that in mind...

• More fuel needed to compensate.
• Use lean-spool to avoid being overly rich at part-throttle on the road.

So I'm happy.

Rich

Golden

iTrader: (1)

I was just going to say that... but then when I got to the bottom of the page, Bryan beat me to it.

Here is my favorite setup for them. Just paste it into all 4 maps.
70
73.75
85
85
80
76.25
70
60
51.25
43.125
31.25
20
10
0
0
0
0
0
0
0

Golden

iTrader: (1)

After looking at your post up there, I'm pretty sure that your issue is the load tables. Remember that AFR gauges lag behind a little, and you are usually flying through the load tables pretty quickly. Dumping out of Closed Loop a little sooner makes a pretty big difference in AFR while spooling.

richardjh

Thanks guys. I'll try that.

Rich

richardjh

(dumb question time)

How should I approach the mixtures for the newly-exposed cells in the fuel map?

Rich

Mad_SB

iTrader: (8)

Yeah, I was also initially thinking there may be a bit of an open loop delay in other words after you reach the preset load and tps there is X milliseconds before the actual drop in..... I kind of rulled that out because of the initial rich dip before it goes lean again..... that could however be due to acceleration enrichment function.

Setting the load tables lower would counter the lag regardless of if it time delay function related or just rapid transition related since it would start the stop in sooner.

As for the AFRs in the newly open loop areas.... just richen them up similar to how the "stock" transitions went for starters then dial them in till you get where you want to be.

richardjh

Cool. So it'll be just a little microsurgery to smooth it from A to B in the extra open-loop cells that need it...



...then I'll give it a whirl.

Rich

Golden

iTrader: (1)

Set them richer. That's what you wanted to begin with.
How rich depends on your AFR.

richardjh

Already lots richer.

This map is tuned so that going WOT at any rpm sees mixtures cross through 12.5:1 at 150 load (with lean-spool OFF). That involved setting the spool-up cells to steenkeeng reech. But I shelved it due to concerns about why I "needed" to do this, whether the readings were sane, etc. Concerns that have been put to bed thanks to this discussion right here.

Once I see what's what with the revised open loop tables, I'll revise and refine.

Rich

Golden

iTrader: (1)

Don't forget that lots of overlap at lower RPM can cause air to flow in cylinder then right back out the exhaust before the exhaust valve closes. This unspent air / fuel will cause your wideband to read lean.

Mad_SB

iTrader: (8)

Very good point would show false lean just like a missfire with enough overlap.

richardjh

Okay. Would you class overlap as per the the MIVEC regions below as "lots" or "enough", w.r.t. affecting wideband AFR measurements?...









Rich

Golden

iTrader: (1)

Do a log with MIVEC logged and your wideband. That is the only way to really know. The Intake cam ramps up a little slowly, and the exhaust cam ramps down very slowly. So the chart above doesn't say much for the actual timing.

richardjh

Logs! From Blammo!


Attached. Note: My uploaded zips always seem to require an extraction, a rename of THAT file to .zip extension, then a second extraction.

Rich

edit: The ROM used here does not have the "earlier Open Loop" adjustments we discussed. That's still in the "pending" tray.

richardjh

I've now dropped the open-loop mod into my ROM, and am checking the mixtures on-road.

It really does seem to be the case that I have to add a lot of fuel during spool-up in order to get the wbo2 reading what I want. See the shape of AFRMAP here versus the measured AFR...





Here's a quick pic of the MIVEC behaviour...





I'm inclined to think the measured AFR is representative of what's actually going on in the cylinders, but I could be wrong.

I'm basing my opinion on some testing I did earlier in the year. While trying to get "ideal" AFRs, I stuffed up - hit a lot of knock (and I mean a lot) when getting on-throttle around 4000rpm. I added a bunch of fuel back in, re-tested, revised/repeated etc. until I worked out the borderline fuel map settings in the spool-up area that resulted in knock-free operation.

I've cross-checked those particular map settings against the ones I'm now using as a base... the ones that use very rich AFRMAP to get "reasonable" wbo2 readings... and they are very similar indeed.

However, I don't exactly have years of experience in this, and I could easily be getting something a***-backwards. That's why I'd like someone more experienced to look at this MIVEC during spool-up biz, and telling me what effect it is likely to have on (a) real AFR, and (b) measured AFR.

Rich