DIY LTCC or similar system for LT1s

[spfautsch]

I suspect you have an air leak in the evap system. Canister, fuel tank, or somewhere in the middle.

That's certainly a possibility on a 25 year old car w/ 170k miles on the clock. When I have time I'll dig into it. Honestly I can't say I'm sure where the charcoal canister is on a y-body. I've already replaced all the soft vacuum lines on the car. Whatever the case, I'm hoping this might explain my very low TPS cruise surge / miss that I've been chasing.

When you switch on the ccp it doesnt get pig rich at all, It even leans out more. based on blms.

I'm glad you noticed that - I've never messed with the canister purge solenoid but that fits a few scenarios that could explain my difficulties.

When I turn on ccp on at idle it gets pig rich immediately and blm dropping to 108 and closed loop freaks out.

That's a much more pronounced change that makes me wonder if you aren't seeing raw fuel sucked past the canister, into the evap line and then the intake plenum.

I also scored some document with description of the dwell tables and scalars used with ls1 coils, regarding startup and coil temperature. It is freaking modelling with tons of variables to predict coil temperature, so it is indeed the coil temp related than coolant temp.

Yeah, as I'm certain I've mentioned this previously - coil temps != coolant temps, so the phrase "I told you so" comes to mind. I think I'd mentioned creating a multiplier variable or filter function or linear equation for the controller that would allow the user to describe the relationship between coolant temp and coil temp based on where the coils are physically located (on the block or fender, etc.). There's all kinds of under-hood airflow modeling and coil mounting minutia that comes into the picture as well, not to mention ambient air / intake air temps. It's a crap-ton more complicated than a+b=c. Although, on a side note I don't believe any of this is necessary to make a very functional system.

To post some positive news - over the previous holiday weekend, when I got tired of working on household maintenance drudgery I spent some time gathering photos for the PCB assembly manual. I also found a better quality DMM and uncovered another variable that fine tuning of improves the voltage sense logic. The results have been extremely promising on the bench. Hoping to have the PCB assembly manual in a rough draft form soon.

Meanwhile, it's 28F / -2C outside with intermittent flurries so I doubt I'll log any miles on the Green Monster this week, possibly even this month.