DIY LTCC or similar system for LT1s

[kur4o]

I really hope to test the update soon. It does sound really promising. WIth the possibility to dial on the fly some offset and test wot times with fatter and leaner dwell.
It also opened the door to some auto tune logic if there is enough cpu power, finding the best dwell, not sure what we can use for feedback.

I think the current table setup is workable enough and gives some edge over the traditional GM tables design. You will likely loose some rpm vs volts spread but within the usable 11-15 volts it is pretty acceptable.

Finding the weak points that can`t be worked out can gives us a better idea which coils will work best on the broader range. ANyway it is some hack job of very old technology and not all can be perfect.

For the multispark. We might need minimum off time scalar. The time the coil discharges. To take advantage we might just disable on rpm threshold, where the minimum 1.5 dwell at least cant be reloaded fast enough to give a spark before the piston reaches bottom.

We also need to find where will be the best time in degrees to apply the second spark. Something like an EOIT target but for dwell. I guess some realtime control for second spark delivery can gives us an invaluable feedback what needs to be done.

I will take a look at what is designed by gm and hopefully get some fresh ideas.

[spfautsch]

... WIth the possibility to dial on the fly some offset and test wot times with fatter and leaner dwell.

While I'd love to hear your feedback, if your transmission is struggling to deal with the torque you might want to lay off the WOT passes.

I will take a look at what is designed by gm (on the subject of multispark) and hopefully get some fresh ideas.

Sounds good.

I think the auto-tune idea may be premature. Unless / until misfire detection can be made to work reliably, I don't think there's enough feedback with only MAP info. Still, being able to adjust dwell on-the-fly was eye opening. I would have never thought to take more than 50% of the maximum dwell out in order to see / feel a change.

Will continue to focus my energy on documentation, time based (limp home) run mode, and misfire detection, in that order. I'm also pretty sure I'm going to go ahead and acquire a set of D514a and D585 coils to use for testing with my own butt-dyno.

[kur4o]

Just did some test run with the new firmware. No issues and running strong. Didn`t push it much. Did some fine tuning to get rid of some lean conditions.

It looks like the most important table for maf tuning is the so called maf pump shot coefficient. I came up with some really weird settings with real time control and now the car runs 100 times better on part throttle take off. Pulls really strong now.

I will do some write up how it works, and how I set it up. Even the wideband almost frozen and stopped jumping around.


I still have no definite answer how to set the multispark.

There are 3 scalars we need. Some 2d pulses vs rpm. Or 3 ranges 0-1000rpm 3pulses 1000-2000 range 2 pulses, above 2000-1 pulse.
Min burn time. The time the coil will discharge. And dwell time based on the pulse count or rpm count.
Also enable at crank only, at run only or always.

Not sure will there be any benefit of waste spark setup. So you fire each coil twice on a full crank rev.

[syntaxterror]

Outstanding work! I have one question with coding could this work on a obd1 v6 ?
Thanks Joe

[spfautsch]

Not in it's current form. The controller firmware is completely dependent on the opti signaling.

It's possible that it could be made to work once a time-based mode is added, but I've had little time to work on this lately and I'm staring at another transmission rebuild project in my garage now - this time a 4t45e.

[syntaxterror]

Do you still have any boards left to sell? Just something to tinker with.

[spfautsch]

Dozens

Un-assembled kits $25 - extensive soldering required but all through-hole components
Assembled + tested board $75 - soldering required to connect wiring, 1-week lead time, small orders only pls

Price includes domestic shipping via USPS. International orders add $7.50

PM'd you my paypal address if interested

[kur4o]

but I've had little time to work on this lately and I'm staring at another transmission rebuild project in my garage now - this time a 4t45e.

I hope some video how to guide will be made this time.

Meanwhile is it possible for the latest firmware to introduce some delay or lag at crank time. I think it is too subjective feeling, but the earlier version seemed a little fresher on cranking.

[spfautsch]

I hope some video how to guide will be made this time.

You wouldn't want to watch 18 hours of me slogging through this in the July heat. I'm hoping this is a simple case of one molded piston that's disintegrated, but that doesn't make the project any less involved. While I have the powertrain out I'm going to replace the timing chain guides and a leaky valve cover seal. Also, GM used what I would call "biodegradable" wire loom during this era (2008 Pontiac G6) - it literally crumbles when you touch it so I'll probably replace a bunch of that while it's easy to get to.

Meanwhile is it possible for the latest firmware to introduce some delay or lag at crank time. I think it is too subjective feeling, but the earlier version seemed a little fresher on cranking.

Yes, you're not imagining it - I've had a couple "funky" hot / warm starts, and a couple instances of the erratic dwell lookup. Ironically, I think I figured out what the issue is this morning during warmup (i.e. when it switches to the high temp coolant table). I probably won't have time to find the exact problem for a few days but I'll do my best.