hey im planing on installing my megasquirt on my s5 na motor prior to doing a tII swap. i have searched to try and figure out how to control the vdi and aux ports but havent found much info. i believe you have to build a circuit to control these. can anyone give me some advice on how to build this and also set up the megasquirt to control them? thanks

 

heres a shot in the dark.. tell me what you guys think. ok im thinking you take 2 outputs from megaskeet. you set them to be actuated off of rpm at 3800 and 5500. you then run those 2 ouputs to to relays. those relays then supply a ground to the aux port solenoid and the vdi solenoid respectivly. i was thinking of using the relays to isolate the solenoid ground from the megasquirt.. to try and keep down on any noise... so what do you think? is the whole 2 outputs base off of rpm actully possible with megasquirt? if it is is there a way to actuate off of load instead? it seems like load would be a little more appropriate in calculating when to lengthen the intake runners and when to open the aux ports..

any advice is welcome.. its about the only thing holding up my megasquirt install.

 

Sounds like a good plan ... I'm pretty sure you can set the outputs to just about anything in the pull down menu, rpm and map do come to mind, however it seems you can only choose one at a time ... I also remember seeing a solenoid aux port control mod here on the forums ... HTH

 

yea i also caught wind of a mod to megasquirt to run vdi.. but i cant find any info about it so im making up methods..

 

Read the FSM, figure out which solenoid us used to control the VDI. Wire up one of the spare outputs from MS (see MS documentation for details) to drive the solenoid. Drive via relay to avoid overloading the output, or build a higher current output like the typical fast idle mod, and you could drive directly.

 

Yeah, tofuball and I originally ran the VDI and AUX ports on his S5 when it was the only one running stock ignition with the megasquirt.

We built 2 transistor circuits on a separate board (now could be done in the proto area), which drove a couple of relays, which actuated the solenoids. Tofuball had removed the air pump, so we were using an electric air-pump with a pressure-activated shut-off switch to operate his VDI and AUX ports.

Ken

 

thanks! i believe this is the mod i have been hearing about. so are you running a setup like this? if so are you triggering off of rpm? or is there a way to trigger off the engine load?

i guess i could do some more reading to figure the last part out but just figured i would ask.

thanks again.

 

i havent thought about it much yet but would you be able to trigger the event off of load? i would guess you could look at rpm and manifold pressure to determine a value for this.. it seems to me that the timing to lengthen the intake runners would be different if the engine was under a light load rather then a heavy load.. i could be wrong about this.. i dont have a great understanding of how megasquirt manages the outputs either, so i was curious if megasquirt has the ability to trigger events off of engine load..

 

yes. It can. It can trigger an output based on just about any parameter. However, it can't currently trigger an output based on multiple parameters.

 

"Load" isn't one of the parameters that can be used directly. However, given it's a tuned resonant intake you are working with, rpm only is likely a better choice. Do some searching on this forum regarding how the stock system works, and emulate that to start with. Also read up on the capabilities of the outputs in the MS documentation:
http://www.msextra.com/manuals/MS_Ex...nual_Index.htm

 

"load" can be used if by "load" you mean "vacuum," or the signal from the MAP sensor, which is what I was assuming.

 

so you can not do, say, an output based on RPM and MAP/TPS reading?

if you can't, one way to do it is just have another output driving another relay inline to the aux/VDI relays.

the aux port opening is fairly dependent on load. the stock ECU also depends the VDI on load (in addition to RPM of course) but it's less important. you're probably not going to be at low load at >5500rpm all that much anyway.

 

Yeah, the MS1 cannot take inputs from multiple sources to control the generic outputs.

 

yeah i understand.. im about to build the circuits to control a couple relays. im just going to base the operation off of rpm. its only temporary any way. im building a s5 turbo motor to install, but i wanted to have a operational megasquirt first. that way i dont have to try and figure out how to use the megasquirt at the same time im doing a complete tII swap. i cant afford too much down time.

coldfire:
if i understand what your saying about using 2 relays.. then i think you have the wrong idea. if you have 2 relays inline, and they are controlled individually by rpm and map. then the finaly operation will be a function of a) the rpm that you set. so no matter what it will not open any sooner then that rpm. and b the map value. if the map value is achieved before the rpm then the operation is soley based on rpm. however i dont know what a map reading looks like thru an rmp range so i dont really know how much functionallity you would gain by controlling it by both. it just sounds like more of a hassle then just using rpm as a trigger. idk.. not saying dont do it.. just i wouldnt.

 

well i wasn't saying i was going to do it that way, just a suggestion. and using the relays inline should work like stock. for example if you have the RPM relay first and then the LOAD relay, then the solenoid is only going to be ON if both relays are ON, which will satisfy two conditions. for example RPM>5500 and LOAD>50% (whatever that may be). so ultimately the operations is dependant on both RPM and LOAD.
which is what the stock ECU does. except without relays.

my question here though, and perhaps i have just overlooked this or not read enough, but why is a relay needed if you are using a properly rated transistor circuit? i am pretty sure the stock ECU doesn't use a relay for any solenoid controls.

 

If a properly rated transistor is used, and the circuit is protected from coil flyback with a diode, it'll work just fine without the relay.

 

i was going to build this circuit. im sure its probably fine to directly run the solenoid but.. i was just to lazy to figure out for sure.. so i was going to use a relay just to be safe.

 

Do not trigger the VDI and aux ports to open off of load they arn't there to function as a throttle devise, they are there to function as a tuning devise.

The point of the aux port is to keep intake velocity high in the primary and secondary ports until a point at which become a restriction at which time they open. Without enough air volume achieved at the higher rpm (not load) the velocity in the port won't be enough to sustain more power.

The VDI has to do almost completly with pulse tuning also changes with how fast the intake pulses come and not load on the enigne. At lower rpm the intake pulses come slower and resonate around the plenum and reflect back in a certain amount of time. The rpm at which that pulse returns to the opening of the intake port just as it closes will allow it to force more air and fuel into the chamber just before the port completly closes. Once the RPM drops or increases past this point the plenum volume can no longer aid in pushing more air into the engine. VDI allows that plenum volume to be changed as the RPM increases so that the pulses can continue to hit the port at the right time to make power.

Since both of these devices require higher rpm to get the proper amount of volume and frequency of pulses to work properly opening them under load will only help power and drivability if the engine is loaded at the rpm in which they need to function properly. If you look in the 2nd gen dyno section you should be able to find some people who did several runs on a dyno to tune when their Aux ports open, if you find them you will probably see that when they where opened too soon, power dropped for a couple hundred RPM until the engine speed got higher.

If they can be easily triggered off of RPM, just use that and save yourself some headaches.

 

dont worry im going to trigger off of rpm.. 5500 - vdi and like 3200 for aux ports.. any way its only temporary.. im installing it on my s5 na to get familiar with the megasquirt, and to make sure it works.. that way when i do my TII swap it wont be as much of a hassle.. ie: i only have to swap complete TII drivetrain and motor.. apposed to that plus installing a megasquirt and figuring out how to work the damn thing..

 

lol, I was going to do the same thing except I never built a rotory before, so now I"m building an N/A, then megasquirt, then turbo megasquirt, hehe

 

hmmm, well interestingly enough this is what the S5 FSM states for 6PI and VDI solenoid operation:

6PI inputs: Airflow Meter (AFM), Water Thermosensor, Crank Angle Sensor (G+, G-), Neutral Switch, Clutch Switch
Engine Condition for ON is stated as "Above 3,850 rpm AND (Medium Load Warm, Acceleration, or Heavy Load)

VDI inputs: Airflow Meter (AFM), Crank Angle Sensor (G+, G-)
Engine Condition for ON is simply stated as "HEAVY LOAD" with no mention of RPM, which i think is not true.


This is quite interesting because those inputs are not what i expected. not quite sure how the ECU uses those inputs as conditions to activate the solenoids. all i know is from testing, the neither the 6PI or VDI solenoids would operate on just RPM, it was taking other factors.

One important thing to note though is that the VDI solenoid is inline with the 6PI in terms of vacuum-hose routing, so the VDI needs all the conditions the 6PI needs, in addition to any conditions in might have itself. hope that makes sense...