MSefi.com read only forum (Jan.15,2018)

I have a 4-1 cam wheel that I am using on MSI with a batch fire (2 and 2) injection setup.

MSI gives me the ability to use the distributor 4 tooth wheel to start injection in a 2-Alternating configuration, but I would like to use the single tooth to tell it at what part of the cycle to start injection.

I want to synchronize the start of injection with the engine.

Is this possible in MSI? Has it been implemented in MSII? If it has can you please point me to the correct information?

Thank you!

No one has run into this issue?

Thanks Lance. A lot of batch fire cars from the early-mid 90s have a 4-1 cam wheel to sync start of injection with the engine cycle so that it is optimum for idle and low engine speed.

If the MS was able to sync the start of injection according to this secondary ignition signal it would improve idle in a lot of applications.

Of course with full sequential injection, a crank and cam wheel can be used for full control but until then, such an improvement would be welcome.

Lex-

I brought this up not too long ago, and Al thought it would be an easy fix into the code for the next version, but I'm not sure what came up of it, as I know he has been super busy with several projects. I didn't think it would be a trivial fix as he had mentioned, because I don't see in the current Megatune where cam sync settings were available.

I agree, I think it would be worthwhile and would find benefit at idle without going full sequential, but as long as they are working on the sequential product, I won't pester.

Here is the thread with a picture I drew in an attempt to articulate the concept. viewtopic.php?t=28967&highlight=

Scott.

Thanks for the reply Scott, I have experimented myself with different sync setups and have found that some make the car run much much better at idle and prevent misfires while allowing a stoich A/F ratio. This is what is needed to pass emissions.

I would love to see something like this implemented and I am certainly not the only one that is having the rough idle problems.

The motor I am running is a 1.8L DOHC BP Mazda (Miata engine)

d'oh... i just noticed in the drop down box of advanced ignition options where it says dual spark options is where cam sync can be selected. now i realize what Al was talking about it being an easy fix on the next version as far as starting syncing cam signal after cranking.

i think this is much closer than you thought. maybe we'll get an update.

TheMonkey wrote:d'oh... i just noticed in the drop down box of advanced ignition options where it says dual spark options is where cam sync can be selected. now i realize what Al was talking about it being an easy fix on the next version as far as starting syncing cam signal after cranking.

i think this is much closer than you thought. maybe we'll get an update.

I hope you're right. How can we follow up on this?

i read through a bit today trying to get a handle on this.

read through the section in MicroSquirt regarding 'Dual Spark'. http://www.microsquirt.info/

seems that MicroSquirt is setup for Dual Spark already, but with an MSII, we can do a mod to the daughter-card so that we can use the dual spark options in MegaTune. the mod is to re-route some traces on the 'NAND gate' (do a search on that term). sounds like it's a pretty serious mod, but if anything, this project has boosted my confidence. from what i have read, by doing this mod, you give up your PWM flyback circuit (low impedance injectors) so that you will use the injector 1 PWM pin for 2nd ignition IN, and use the injector 2 PWM pin for 2nd ignition OUT.

i use high impedance injectors, so this is fine, but if you have low impedance injectors, it sounds like maybe you can still bypass the PWM circuit by using some resistors, but i'm not sure, i didn't read too far into that.

it's not clear that anyone has done this to ONLY phase the cycles for the fuel injection banks as we are discussing. seems this is in place mostly for odd-fire motors, 2 cyl sequential, or 4 cyl wasted spark.

couple questions i have at the moment, and maybe someone that knows the answer can answer:

- can 'dual spark' mode be used to ensure bank 1 is injected after cam sync, and still only use one ignition out? can the two ignition out pins just feed one wire?
- where is there more details on the NAND gate mod?
- how do we externally wire into the PWM pins? are they already connected to DB37 pins?
- what type of signal to we need to bring in from the 2nd cam sync signal? if i have a VR sensor on my cam, can i send in the VR signal, or should i condition it through an HEI module, or build another VR conditioning circuit with the same specs as the one on the 3.0 board?

i'll wait to hear from anyone with ideas on this, and if i feel encouraged at all, i might give it a try and fool around with it on the bench. i think my motor is a fine candidate to get a bit better idle, but it's working pretty good as it is.

I am bumping this topic.

I am very interested in find a solution to synchronizing injection with the cam.