Tuning Transients

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.
FrankCorrado
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Tuning Transients

Post by FrankCorrado »

Is anyone good in how to determine the engine specific requirements for tuning transients?

I am having a very hard time with those and apart from cold very long cranking issues, it's the only thing I can't tune yet.

I'm not sure I should detail my actual problem, cuz I am asking if someone can explain how to determine the engine requirements, how to understand what the engine wants and then how to use DTA to give it the right way (it would then be valid for any engine). But if someone would be in context I could explain the situation I fight against, as a FYI.

tnx
Frank
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86sixsix
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Re: Tuning Transients

Post by 86sixsix »

alright 'stranger'... you've all the tools you need already to do some basic stuff..

*****>>>>>transients can only be done without proper test equipment when you have a 100%-perfect-to-the-microsecond main fuel map.<<<<<*****


you have:
a posh DTA ecu that can fast log
e-race

you don't have:
to make the maths easy is your air/fuel ratio set to lambda, not AFR.


turn cl off, set all transients to 0, power cycle ecu, set ecu to fast log, idle, stamp on throttle as hard as you can. turn the engine off and get the log up.

using a pencil, a bit of paper and a calculator... watch the log. you know what you want the lambda to be already from your cl target and main maps so if you're engine's revving at 1500rpm that's 25 revs a second. so if you target lambda of 1, the log shows 1.1 for 1 and a half seconds then you want a tip-in of approx 10% for 38 turns.

don't play with pedal speed unless you go by the name of clark kent at the weekends and remember...just because there's a box in dtaswin - doesn't mean it *must* have a number in it.
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FrankCorrado
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Re: Tuning Transients

Post by FrankCorrado »

I'd say 95% ready, so I'll continue smoothing it out before, then. I wouldn't want a number in the map not perfect to interference with transients results.

I didn't know it was possible to adjust transients without driving and just by stamping on the throttle standing still from idle, without any load on the engine. Easier this way then, as I won't need someone sitting aside and playing with numbers while I drive. :)

I agree having lambda instead of AFR here would be much easier.

Well I'll keep that on my to-do list once I get a smoother OL map.

I think pedal speed is set at 30ms or 50ms in my map.
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Re: Tuning Transients

Post by 86sixsix »

FrankCorrado wrote:I'd say 95% ready, so I'll continue smoothing it out before, then. I wouldn't want a number in the map not perfect to interference with transients results.

I didn't know it was possible to adjust transients without driving and just by stamping on the throttle standing still from idle, without any load on the engine
good thinking. because everything's %s here too - it has to be right before you start or you end up 'chasing the track'.

there's always load on an engine, but how much load doesn't matter coz your main fuel map's perfect :D ...or will be soon anyways.
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Re: Tuning Transients

Post by stevieturbo »

I cant really see why you would need logging of any kind. It is quite easy.

Tune your fuel map with transients turned off.

Then when it's acceptable, or even good you can start the transients

Turn them on and start at zero. Stamp on the pedal. If it falters, add fuel. Keep doing this until it doesnt falter.

Job done.

AFR's are unimportant, and you'll waste your time trying to chase them.
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Re: Tuning Transients

Post by 86sixsix »

the thread starter's been mooching and running around with a poor CL fighting against his transients for ages - only reason why i'd say log everything.

edit: and again, for the thread starter, afr's *are* important. it's a quick and dirty way for him to get what he wants without spending any money.
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FrankCorrado
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Re: Tuning Transients

Post by FrankCorrado »

Were did I say AFRs were important for transients?

As long as it does not buck or cause a driveability problem I don't care about the transient afr. I have a very good idea within which threshold the afr won't make the engine buck, so in a way I target something in between these limits, yes, but there is no precise afr I target for transients. All I know is the actual afrs I get cause the engine to buck and wilder the wider I open throttle.

Again, I am not fighting against any transients, as they are off since somewhere in July. I let CL try to smooth it out and do its job.

Like most people the less money spent the better, you told me using CL to smooth out a map would save the money of a dyno run, so I listened to your advice. :) And so far it works quite well (though I was skeptical at first), only the transients I have never seen improvements in and it seems CL is too slow to "see" the transient situation happening. Which means I may have to map transients after I get a nice "normal" map, which is the reason of my original post.
Frank
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86sixsix
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Re: Tuning Transients

Post by 86sixsix »

sorry frank, i was talking to stevie.

to you, frank:

i maintain AFRs are handy dandy quick and dirty way of getting close to what you want without getting your money out or hurting your engine any in a pretty short timeframe.

i only suggest the AFR way as it's pretty easy, gets pretty good results and at the end you've a load of paper and sums and logs that you can look back on and you'll be able to double back on yourself, see what you changed, when, by how much etc etc.

stevie's way... throw fuel in if it doesn't feel right may also work - i haven't tried it.
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Re: Tuning Transients

Post by stevieturbo »

Transients are ONLY about feel. There is no right AFR.

The only right settings are the ones that give you the crispest throttle response.

And CL will never ever ever ever resolve transients. Once again, turn CL off, and then tune.
FrankCorrado
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Re: Tuning Transients

Post by FrankCorrado »

Ugh, I'm so sorry! I thought you meant having the perfect AFR for transients was what I was looking for and that it was stupid to think chase afrs. Cuz that's mostly impossible anyway, how can I know which afr is best for the engine during transition, that's too much. I know what's bad for the engine, cuz I experience it every time during transition, but as long as the engine is happy I will too, even if the afr is not optimal (13.0 real-time but optimal is 14.0, I don't mind at all :)).

And I see your point, you mean that using afrs for tuning transients is important for me cuz it's a good way, a measure, to save money of a dyno (not afrs are important to me cuz I don't trust any other way of tuning and that 14.6 is not 14.7, I thought you meant that loll). I had a bad night, I've read all of your answer the other way around. loll Sorry about that.

I am not in a hurry to try something for transients as I feel the map can tune itself more, but it will come shortly, probably. And I am very curious to see how it would show on fast logging, who knows what I could find there.

The stevie way, I thought of something similar, increasing my entire map by say 50% fuel and see how the engine behaves in OL. Not the transients maps, the whole main fuel map! I mean if I increase by that much and I still get the same afr readings (too lean so engine bucks wildly), that would kinda be weird, hey? What would you think of that test? It's super quick to perform and does not alter my CL map tuning at all as CL would be off.

My theory behind this test is if right now I cruise at 14.7, nail it down to 75TPS and I see afr of 20.0 I would think that logically if I increase by 50% and then cruise at 12.5 (example), nail it down to 75TPS in the same weather conditions, what would happen? Would I see 20.0 again? Or would I see something like 17-18? I am trying to understand my engine here, for transients behavior. Therefore I am trying to see a pattern, that's all. Maybe it's useless and I would lose time and should go straight to tuning by either fast logging or stevie way, who knows...

Now, speaking of "perfect" map. What is a perfect map for you? One for which in OL every cell hits its corresponding cell in the Lambda Target map? Or every cell makes the engine feel happy, no matter it's 13.8 real-time when it should be 14.7 in Target map? Cuz I am at the latter point, except maybe for cells I rarely pass through, therefore CL never passed enough to do the right adjustment, but for 95% of the cells I usually pass through, the engine feels happy if I run OL for a check, but I may still be off a little on many of them (nothing anyone would feel).

tnx
Frank
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