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By apollard
#14938
The EFI ITB setups I've worked on were BMW M series, and all used mass air flow, not MAP. The others were carbed 2 cycle outboard engines.

However, everyone I've seen has had a 'balance tube' (for lack of a better term) that shared vacuum between the throttle bodies (circled red in the picture). This is also where the vacuum for accessories is derived. The connection to the throttle body bores isn't large enough to affect the idle setting for each (for example), but it is large enough that it does show engine vacuum changes accurately on a gauge. Could you not use that tube to measure MAP and use the Cycle Average MAP setting in TunerStudio?

I would think this might be the place to start experimenting.
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By Taïchy
#14940
noisymime wrote:So I've done a bit of reading, but like PSIG mentioned, there's a few different strategies that all get variously lumped under the term 'ITB mode'. Different ECUs use different methods and to date I don't feel I've known enough of the real world implications to be able to make a call on the 'best' way to implement this. There are also other considerations such as how auto-tune will function with blended tables etc.

If anyone has genuine hands on experience tuning ITBs on other aftermarket ECUs, I'd love to chat about it though! Whilst theory is great, I've read more of it than I care to at this point and would really prefer to hear from people who have used different methods and what they thought of them.

I have already mapped with some ITB configs and can help you at this subject if you want... :!:

I have worked with ITB on some race cars...
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and with OEM ITB application on some BMW M serie same as appolard has cited before...
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And I agree again with appolard about use of MAF instead MAP. I have not ever seen an OEM ITB setup with MAP except at barometric correction usage. (I dont says that does not exist one, but i not know him.)
By alessandromeyer
#16176
Taïchy wrote:
noisymime wrote:So I've done a bit of reading, but like PSIG mentioned, there's a few different strategies that all get variously lumped under the term 'ITB mode'. Different ECUs use different methods and to date I don't feel I've known enough of the real world implications to be able to make a call on the 'best' way to implement this. There are also other considerations such as how auto-tune will function with blended tables etc.

If anyone has genuine hands on experience tuning ITBs on other aftermarket ECUs, I'd love to chat about it though! Whilst theory is great, I've read more of it than I care to at this point and would really prefer to hear from people who have used different methods and what they thought of them.

I have already mapped with some ITB configs and can help you at this subject if you want... :!:

I have worked with ITB on some race cars...
WP_000096.jpg
and with OEM ITB application on some BMW M serie same as appolard has cited before...
DSCN0522.jpg
And I agree again with appolard about use of MAF instead MAP. I have not ever seen an OEM ITB setup with MAP except at barometric correction usage. (I dont says that does not exist one, but i not know him.)

In the MS world ITB-Mode is really "just" the blend of TPS with Map and I would love to see it the same way as it makes for a simple setup and works for quite a lot people just fine without the hassle of MAF or the likes. Any chance @noisymime?
By BigMac
#18375
Hello
When I tune ITB's which is quite a lot I just use Alpha-N and don't use any MAP signal at all . I never had a problem getting a good idle even with oversize throttles. The biggest problem is with the area just off idle when a small amount of throttle give big increase in air. If you want a "moms car" easy tune smooth ride steer clear of ITBs just like all OEM car producers have ;)
By alessandromeyer
#30788
I know it has been a while, but any news on this?

I would even try to create something like a Pull Request but there is just too much stuff that I don't know about (yet).

- How would I approach this, assuming I would need to implement it in a MS compatible way so that TS could actually configure it
- What functionality would i need to touch presumably?

Just to recap: ITB mode in MS is TPS for low revs and MAP higher up, sort of a hybrid approach because map doesnt work so well low down. Plenty of people seem very happy with this on MS.

Thanks a lot for any hints on this.
Alessandro
User avatar
By PSIG
#30791
alessandromeyer wrote:
Tue Dec 18, 2018 6:42 pm
. . .
- What functionality would i need to touch presumably?
This is the primary question before any effective dev work can proceed. There are many concepts to ITB fueling that appear to 'work', but duplicating an existing method may not be the best path. I think this is one reason @noisymime is currently running ITBs on his MX-5 (and quite happily I hear), in order to gain some perspectives on the best path to take at this point for Speeduino.

If you want to take a shot at using a dedicated ITB control system; you could duplicate the "MS" style as a test reference, or create a multiple MAP system, or IMAP/EMAP, or one of several switching or blended load sources, etc. Examples of the last one could be 1) hard-switching of load source from TPS to MAP at adjustable points in RPM or load. Another could be blending the load sources as percentages across RPM, e.g.:
RPM--------->
MAP 0-100%
TPS 100-0%

There are many potential options. I would try some of the ITB features already in Speeduino to get some reference experience. Pick your path with research ideas or a flip of the coin, and take a shot!

David
By Billzilla
#30793
FWIW I ran a 4AG (about 185 hp, 8,600 rpm) years back with a Motec M4 using TPS & revs only for load sensing. It was used on a road car, it drove quite smoothly and when driven normally was also pretty good on fuel. It worked quite well and I wouldn't hesitate to do it again.
By alessandromeyer
#30948
PSIG wrote:
Wed Dec 19, 2018 12:03 am
alessandromeyer wrote:
Tue Dec 18, 2018 6:42 pm
. . .
- What functionality would i need to touch presumably?
This is the primary question before any effective dev work can proceed. There are many concepts to ITB fueling that appear to 'work', but duplicating an existing method may not be the best path. I think this is one reason @noisymime is currently running ITBs on his MX-5 (and quite happily I hear), in order to gain some perspectives on the best path to take at this point for Speeduino.
Why is it that it may not be the best method to duplicate something other seem happy with? I'm an Alfa Romeo-Guy and people over at the biggest alfa forum (alfabb.com) use the ITB Mode with Megasquirt quite happily. Most people said it is a big improvement over Alpha-N only, especially at WOT up high and respectively with (single) MAP low down. I know about the alternatives with multiple maps - but when there is a way to solve a problem in Software only why not go for that?

You're correct though that I haven't tried and compared personally.

Thanks
Alessandro
User avatar
By PSIG
#30950
alessandromeyer wrote:
Mon Dec 31, 2018 9:57 pm
... Why is it that it may not be the best method to duplicate something other seem happy with?
It's both the method and the ability and best way to implement the method on the processors and code Speeduino uses. Speeduino has gone down a few paths that were not the best, and some have been recovered or reconfigured successfully; but others we will just have to live with as they are too rooted to change now. Now is the time to make those determinations of best method(s).

Consider if you have been using a pocket knife to cut trees down, I'd bet you would think an axe would be freaking awesome... until you find you could have used a chainsaw if you had taken a little time to discover that. :lol: I think Josh should be given the time to find the way that will result in "ITB mode" being awesome the first time. It may go quicker if you can offer him help in some way. Perhaps try some of the ITB features already in Speeduino, and let him know what does or doesn't work well for your engine. Having different experience on different engines and tuning methods can be very valuable.
:?:
David
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