For anything you'd like to see added to Speeduino
By Tjeerd
#26590
Hi

We are running 2 squirts per engine cycle. I assume one engine cycle is a 720 degrees (all cylinder fired once). That is why there are problems with the imbalance. When using 4 or more injection per engine cycle this would not be a problem I think. I will try this 4 squirts per cycle again but if I remember correctly there were also some problems with this. Probably dead time related.

I assume there is an imbalance because the outer cylinder valve wear a lot quicker than the inner cylinders. This can have other reasons of course. I did not measure exhaust gas temperatures or O2 per cylinder bank.

We did test with the valtek type 30 injectors. http://www.valtek.it/en/products/injectors/type-30 and the
Barracuda BR124P 4CYL Injectors Rail. I may have the number of 4A peak and 1A hold wrong (should be 4A peak and 2A hold) if I look at the datasheets. It was a long time ago :-D.

After the whole system not working very reproducible with the resistors and the duty cycle did go way higher than expected. We thought the injector drivers where the fault and opted for a known working system of injector driving to make sure that was not the problem. On resistors the injectors would actually open and close, but somehow we needed maximum duty cycle way before we anticipated. Even with all restrictors removed in the LPG nozzle.

We still have some trouble with the system as it is not reproducible we cannot get it to have the correct mixtures from the table alone and need a lot of EGO control to keep it in check (20% or more). I suspect the LPG pressure/temperature and need to buy a pressure/temp sensor and start logging to see if this is indeed the case.
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By PSIG
#26596
It would appear that one injection per-cylinder each cycle would produce even gaseous vapor distribution in a 4-stroke. This can be done with Speeduino (example 4-cylinder) using 4 injectors on 4 channels TBI in basic non-sequential 1-per-cycle, or 2 injectors on 2 channels at 2-injections per-cycle alternating, or 1 injector on 1 channel at 4 injections per-cycle. This should not be a problem to obtain even fuel distribution. More cylinders would only need more injectors or more injections, or optionally both, limited only by flow and latency.

I did not see injector datasheets on the linked page :?: , so if any of that is available, it would be helpful for researching effective drive methods.

David
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By PSIG
#26601
Thanks, Tjeerd! :) Wow, those injectors are sloooow. While this may present a problem for idle/cruise fuel control and multiple injections per-cycle, solutions exist, such as variable pressure control with MAP or throttle reference. Look at the bright side — there are workarounds and solutions to the known issues, so start your project planning and let's make it work well!
Image
David
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By PSIG
#26624
GMC270 wrote:
Sat Jun 23, 2018 8:36 pm
Wow, those injectors are sloooow
So we need peak and hold injector control after all??? :lol:
Ha! That was looking at the OEM specs that used P&H control. I have no idea if they would be any worse using any other control, but if they're relatively slow with P&H, other solutions for high-revs or fine control with multi-shot are still there if they are so bad as to present problems. I think that's unlikely for most applications, but I was surprised by their latency at such low pressures. It's an adventure! :lol:

David
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By TonySandberg
#26633
I have built a Speed pcb with P&H and running GM 2bbl TBI with it. Copy the Diyautotuns old tbi settings 4squirts alternatig. nott working with Speeduino. the duty stops att 24.5% !?!?
With MS2 no problems.
so i am stuck :-(
By theonewithin
#26640
TonySandberg wrote:
Sun Jun 24, 2018 10:16 pm
I have built a Speed pcb with P&H and running GM 2bbl TBI with it. Copy the Diyautotuns old tbi settings 4squirts alternatig. nott working with Speeduino. the duty stops att 24.5% !?!?
With MS2 no problems.
so i am stuck :-(
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