yes i still need the offset, cause i dont know what the actual timing is, its just close enough tomake the car barely run...but it runs, which means this sensor will work

and you cannot use the opti to trigger the ignition portion of the megasquirt, it will only work if you drive the megasquirt off the coil or tach signal, and then use the stock comptuer for spark, and the megasquirt for fuel

 

ok so the car is up and running smoothly, and after i found tdc, and made a makeshift timing marker, then used the timing light and changed the phasing in megatune, i came up with the magic number of -14degrees of offset...i could be a little off, but its close and runs very smoothly with timing locked out at 15 degrees...yeah im copying the turbo mustang guys and running locked timing, ill probably go up to 18 or 20 degrees now that i have the phasing dialed in.

 

THat is cool, what type of coil/ ignition module are you using?

 

im using the high current ignition driver that is built into the megasquirt II board, and im just using a standard msd blaster II cylinder coil

 

Wow.. so just a coil and thats it?

Damn thats really nice.. The only thing I don't like is that information is so spread out on it and the software i've looked at looked a bit on the cheezy side.. I like to see maps i na graph form to look for dips and such.. What software are you using?

 

well im going to make a write up so that the info is not so spread out anymore...this is a great system, and to my knowledge...im the first to get it to work on an lt1...so now everyone else can just copy what i did...its pretty simple.

im using the megatune software, complete with tables and 3d graphs for tuning...its actually IMHO better software than lt1_edit

 

Do you have a link to the software?

I swear if mine wasn't running so great right now I would swap it because this sounds really cool

What else did you need with this? Did you use the stock IAC motor? I assumed you just piggybacked all the temp senders??

 

http://www.megasquirt.info/ its on there in the configuring section...only thing is you cannot use any function of the software without it plugged into a megasquirt, kinda odd

the stock computer is hooked up to the opti so my stock tach will work, also hooked up to the trans so i have speedo and reverse lockout, and oil sending unit, basically the stock computer is just hooked up to run my guages, and not controlling anything. i piggybacked to the front temp sensor, and the megasquirt is not reading correctly from it so i dunno if i have too much hooked to one sensor or what, headers are in the way of the sensor in the head, so i hooked both stock wires to the front sensor on the water pump, and the megasquirt to it as well

IAT is an open element gm unit, and only hooked to the megasquirt

yes stock IAC, the good thing about this is that the stock settings in megatune are made for gm sensors, so everything already works with all the stock sensors

 

What an awesome project..

I really wish mine didn't run so well right now.. i'd really like to try this
.

You shoudl make a post in the advanced section or forced induction . It doesn't seem like too many people would appreciate this type of thing in general LT1 tech.

 

You can't run multiple users off a straight resistance load like the coolant temp sensor. As you are already seeing, you get the wrong voltage feedback to both the ECU's and hence the wrong temperature indicated. You need a second sensor for the megasquirt. I have a similar issue running both the stock PCM and the MoTeC ECU. I added an extra coolant temp sensor in the line returning from the back of the heads. Just cut the hose, put a brass "tee" into the line and screwed a temp sensor in it.

 

Interesting story that may relate here. Me and Bryan where working on a project car for one of the race team owners here.

It was a BB chevy with a motec running everything and the stock PCM running the fans/AC, etc.

As you might think.. the stock PCM needs a ignition pulse to decide that the engine is running and its OK to turn on the fans. You know how the fans won't come on unless its way overheated or the engine is running.

We took a traditional crank trigger and fed it to the Low res and opti low reference (ground) and it worked like a champ. In fact the PCM recorded engine RPM with really good accuracy.

The low resolution side of the opti is looking for 4 pulses of different lengths. The lenght (R theta) of the pulse in the wheel gives the PCM a TDC reference .

Our success with this project told me that it should be very possible to run a megasquirt or anything else for that matter off the low res side of the opti. The different on/off times would be a concern but I really dont' think it would be that huge of a deal because I don't htink most crank inputs are quite that sensitive. If anything I think it would just be a touch noisey.

Another option would be a 360/4 signal divider and to use the high res side as they are equal spacing.

 

The Opti has 8 slots = 8 pulses. 4 of them are identical in length, and alternate with the 4 variable length slots.

 

Right but the opti spins half as fast as the crank seeing how its driven by the cam... so 4 pulses per flying pickup crank trigger revs satisfies the opti.

 

its been atemted many times to use the 8x wheel for the megasquirt, with no real success without decoding the wheel (re-writing code in the firmware to mny knowledge is how they do this) check out msefi.com lot of megasquirt info there

 

I understand the relationship of cam rotation to crank rotations. I was just attempting to clarify for anyone that was reading this that in addition to the 4 variable length slots (7* for #8, 12* for #3, 17* for #5, 22* for #2), there are fixed length (2*) slots between each of those for cyls # 1, 4, 6 and 7. The MoTeC ECU interfaces with that signal to provide full sequential injection, while utilitzing the high res signal to allow adjusting the injector timing based on "end of event" or "start of event" reference. Also allows the addition of the MoTeC IEX 8-channel ignition driver for full direct fire ignition, utilizing 8 LS1-style (or similar) coils, with individual igntion timing possible for each cylinder.