DIY LTCC or similar system for LT1s

[spfautsch]

I feel some nice double platinum or iridium plugs will make it even nicer.

I ended up running Denso IT16TT (4713) based on their cleaner (bright blue) spark pattern compared to the OE double platinum AC Delcos.

As a last note I want to Thank you for putting such an enormous R&D time, developing the controller. It is really amazing that it works so good.

Thanks for the kind comments, but much more importantly a huge thanks for investing the time, money and faith to test this on your own hardware. I was really worried for a while there, but I'll sleep better knowing it has your blessings. Be sure to PM me for the prize money.

I also want to do some more videos ... I guess the best place to put them will be on some video sharing sites.

Anything you'd want to do in that regard would be great. My next 3-6 months are looking to be fairly busy so I'll have limited time to spend with hands-on stuff when not at work. Needing to rebuild a 4L60E that's getting ready to drop 3rd / 4th in my wife's daily driver, among numerous other (non-fun) projects.

It is still too advanced for the average Joe but some install guides with a list of the needed parts will unleash demand.

I'm not necessarily interested in "unleashing" demand. In my eyes there's no way to make this a commercially viable product either assembled ready to install, or in kit form. The amount of time it takes to count the parts out, if I were to pay someone minimum wage to do it, would dictate price be triple ($75) just for an un-assembled circuit board kit. Building harnesses, assembling the board and packaging in some kind of case would inflate the price to well beyond obscene.

My intention was to start an assembly and installation guide with accompanying pictures, but I simply hate writing documentation. I will try to suck it up and get going with this. My only other immediate plans are to work on a limp mode in the event of a loss of the high res signal. I'd like to get those two items accomplished this winter, along with building a more formal support forum and info and ordering pages.

Another low-priority item I'd like to tackle is acquiring one of the coils being used on the newer LT-1/LT-2 platforms and develop a dwell map for them. Unfortunately it looks like these use yet another connector.

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Beyond that, I have no immediate plans to forcefully grow the project. I'll continue to support it but my hope is that some of you who have kits will try them, like the results and subsequently develop your own installation methods in order to offer these services to others who are less comfortable tackling a project of this nature.

This is to be considered the best mod on par with ls1 injectors patch.

I may give that a whirl now that I know the ignition controller isn't the cause of my tuning difficulties.

As a side note project I might get access to a spark plug pressure chamber to test some dwell settings.

That sounds great. I have no doubt there can be improvements made to the dwell tables I developed last winter - if there's anything I can do to help let me know.

[kur4o]

The more miles I put on the COP system the better it gets. Last time I completely forotten that the system is present. It has a driving experience completely as stock, with beefed up spark.
You can be sure that the reward will be spent wise on testing equipment.
Big thanks for the support.

The weather is getting worse and more time will be spend when it gets warmer here.

I think that lt1 coils are the same as yours other than being square. They have the same step up driver and use identical dwell tables.
Found some pregapped iridiums that might work well. ac delco 41-101. I will give them a try. Also scored a used set of a double platinum 41-985 that are fine wire, and looks good, but nowhere to be found new. It ill be either new design coming or are discontinued in favor of the iridiums.

I also figured that runing evap system on idle improves it tremendously. CLosed loop gets pig rich and can`t compensate for now. I will try to dial in some of transition fueling tables. It needs to increase the boil time to compensate for the colder heads.

Some winter patching will include figuring out the transition tables and make a patch the will enable evap on idle and work in closed loop or something like that.

[spfautsch]

Thanks for the update - I'm happy that you're happy!

On the plugs, the double fine-wire iridiums easily demonstrated the cleanest spark in free air with the exception of plain copper. Honestly, anything and everything had a cleaner looking spark in free air than the the ACD double platinum "puck" style plugs. The spark jumped around the platinum in dozens of smaller spark showers, and the overall color was more orange than blue.

Looking at what rock auto shows for cross reference those newer square coils appear to be referred to generically as D510C with a GM / ACD part # of 12619161. If I get a chance this winter I'll pick one up and perform temperature and voltage sweeps to get a dwell map.

Interesting stuff you've found on the evap system. It's got me wondering if there would be a simple way (thinking electric water pump) to switch the reverse flow system back to cooling the block first. Hmmm...

I'm almost done with the 4l60e build for the family truckster. Not looking forward to dropping the xfer case and trans out on the garage floor, but desperate times call for desperate measures. I have made a small amount of progress on an assembly / installation manual for this project, but as I mentioned previously writing documentation is less entertaining than the aforementioned transmission swap on the cold concrete floor.

[kur4o]

If you switch the polarity of the pump it migth start working backwards. but the propellers are not designed for a reversed flow. There are other unknowns too. There is no cross-water passage in the intake. It is the flow passage within the pump that points fluid tp heads first. I am not sure how hard will be to retrofit regular SBC waterpump. Than it might work. You will lose the extra advance, cooler heads give. The only drawback of the revese flow system is fuel evaporation. I will test warmer thermostat. What helps best is not the overall coolant temp, but the heatsoacked heads. I guess the heads run good 10-20 degrees less than the block. That is why the coolant gauge on f-bodies always runs much lower the pcm measured temp.

Why not run some PWM relay to slow down the coolant flow, at warmup and at highway cruise to regulate temp above thermostat rating. Some inelligent control algorythm will be needed. You will extend the life of alternator too.

I am sure if we play with the transient fuel tables some improvement can be made. Leaving more fuel soacked heads. Another issues that is not discussed is the spary pattern of the injectors. Those ls1 style injectors can spay sideways and the fuel not hitting hot intake valve. I didn`t check mine, they might contribute to the crap run.
I think the stockers have a cone spray, at the correct angle. I might try bumping fuel pressure to see if that helps too. Hope the pump survives 3.5-4 bar at idle for the test.

If you have the time you can command open loop and turn on the evap. Watch for map drop. If it drops a healthy 4-5 points than a evap patch is on high priority list.

I am interested to measure spark duration for the same coil with plugs with different materials. If the resistance is great it is likely the discharge time to last longer. The platinum with dot pluck should always discharge around the dot pluck since copper have less resistance. Is it made on purpose. I have seen heavily worned plugs. The copper core was rounded around the pluck. That dot might be just for longetivity combined with the less resistance of copper. Also the color of the spark can give some clues but the spectrum must be linked with the energy output. Only pressure chamber will sort good and bad plugs. At least 12-16 bars to simulate cylinder chamber.

[spfautsch]

It is the flow passage within the pump that points fluid tp heads first. I am not sure how hard will be to retrofit regular SBC waterpump.

The water pump and block are both completely different. The water pump outlet passages go into the block and promptly make a 90 degree bend into the heads.

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Why not run some PWM relay to slow down the coolant flow, at warmup and at highway cruise to regulate temp above thermostat rating. Some inelligent control algorythm will be needed.

You're a genius.

If you have the time you can command open loop and turn on the evap. Watch for map drop. If it drops a healthy 4-5 points than a evap patch is on high priority list.

I'll give it a shot the next time I start it up. It's been sitting neglected while I've been building the tranny but I put the pan on that last night. Now I'm looking for volunteers to help R & R it - I'll even pony up for a transmission jack!

[spfautsch]

If you have the time you can command open loop and turn on the evap. Watch for map drop. If it drops a healthy 4-5 points than a evap patch is on high priority list.

Had a chance to start it and let it idle up to temp yesterday afternoon. Unfortunately didn't really see a pronounced relationship between the evap solenoid and MAP, just the IAC counts dropping.



Apparently the evap solenoid can be commanded in open loop (using steveo's v4.91). I didn't notice until just now but mine went incredibly lean when switched to open loop (wideband also reading 1.16-1.20 lambda - 1.20 being 5v / max lean). I imagine this is because I extrapolated my injector flow targeting E0 fuel but am currently running a fresh tank of E10. Whatever the case, I only turned off the evap solenoid after I let it go back to closed loop and noticed the IAC count was still very low. The two dips in IAC afterwards coincided with the ccp solenoid being commanded on / off with eehack.

[kur4o]

I suspect you have an air leak in the evap system. Canister, fuel tank, or somewhere in the middle. When you switch on the ccp it doesnt get pig rich at all, It even leans out more. based on blms. When I turn on ccp on at idle it gets pig rich immediately and blm dropping to 108 and closed loop freaks out. In your case the blm jump even higher.
The ccp is really hard to diagnose, I was running and tuning with stuck open ccp for a year and a half, and didn`t notice the problem. I suspect injectors, fuel pressure, maf, temp compensation for inconsistent tune, but at the end by chance it turns out to be the ccp valve. After fixing it the ind cyl trims were all messed up, including maf table and ve.

You can turn it on without waiting to get warmed up. I am planning to test some transient fuel tables soon and report back. Now looking for some good description of the system.

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.
The more intersting one was EGR dwell boost. I will post the list soon.

[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.