DIY LTCC or similar system for LT1s

[kur4o]

I found some uncanned electrolyte caps in the solder drawer and put them for testing. Will try to find something more reliable later. I hope these are good enough for testing.

Hope to test soon and report back.

The board seem very sturdy and took lots of beating without issues. I wouldn`t have been so nice with the caps if knew they are toast anyway. I had planned to reuse them.

I can try to charge the caps and see if they hold any charge.


I really hope that the caps are giving me the troubles. Can`t wait to test the monster spark output and do some more comparison tests.

[NomakeWan]

It was absolutely the caps, and the fact that all of a sudden it ran like crap and wouldn't run right again is pretty indicative of the problem. Your capacitors are shot, do not rely on them for anything mission-critical ever again. Put new ones in their place, in the correct orientation.

[spfautsch]

I found some uncanned electrolyte caps in the solder drawer and put them for testing. Will try to find something more reliable later. I hope these are good enough for testing.

The bigger the numbers, the better. The ones in the kit were lower ESR (meaning they can charge and discharge more quickly than older chemistry electrolytics). I just copied the arduino power supply section, but I'm relatively certain the low ESR rating was factored into the design.

The board seem very sturdy and took lots of beating without issues. I wouldn`t have been so nice with the caps if knew they are toast anyway.

The problem I'm afraid you'll run into is that after applying a certain amount of energy (heat over time) to the pads, eventually the copper cladding will start to separate from the board substrate and you'll end up with lifted traces.

If you were stateside I'd say chuck it in the trash and I'll send you another kit. But I'm 100% certain you have the only diy-ltcc circuit board in the eastern hemisphere.

I had planned to reuse them.

Trash can.

Think of an electrolytic capacitor as if it were a balloon. There's capacity, or the overall size of the balloon - this equates to the microfarad rating. There's breakdown voltage - the resistance of the balloon to break under pressure. Then there's the equivalent series resistance or charge / discharge rating (ESR). Essentially this could be compared to the size of the balloon's neck - a larger opening will allow the balloon to inflate and (more importantly) deflate more quickly.

What you've done is turned the balloon inside out. It will work as expected for a while, but the internals aren't designed to be exposed to oxygen (reversed polarity usage). Think of the damage that occurred as having holes spontaneously appear in the skin of the balloon (think of how corrosion occurs), until you get to a point where it won't hold air anymore.

This is exactly why the first question I asked after you said it ran for a while and now won't run at all is "did you put the electrolytics in backwards?".

I really hope that the caps are giving me the troubles. Can`t wait to test the monster spark output and do some more comparison tests.

I also hope this is the problem, and I'm on the edge of my seat as well. Listening to your description I think it's safe to say your ICM is shot, or simply can't supply the current the MSD coil needs to charge fully.

[spfautsch]

kur4o has some new caps ordered and is awaiting their delivery. I was hoping to test some startup instances with a dead battery this week to see if I get similar "stuck" coils on initial cranking. As luck would have it I came home to find my PKE system (or who knows what else) had drained the battery below 11v after sitting for 8 days. Unfortunately I don't know if I even have coil indicator LEDs in the board I'm currently running, so those tests may be a week off even though half the work was already done for me. :-\

Meanwhile, since everything else has been great and I've been reduced to tweaking on mundane things like the instant fuel economy constants so the digital dash's MPG calculation matches actual, I thought I'd try pushing the envelope on spark advance. Today I had a first drive after adding about 4% globally to both timing tables (there was some smoothing and extremely high load cells excluded). Oddly, I found some really strange missing at approx 2400 rpm and < 50kpa. After looking at the logs it seems all these were adjacent to instances where 46+ degrees of advance were being commanded by the PCM. I suspect there was no "delivered" spark here - i.e. the EST line wasn't switching low after 46 degrees.

So I'm curious if anyone has ever messed around with the constant at 0x12045 in $EE "Maximum Spark Advance" which is 46 in all the base tunes I've looked at. Since I'm no longer limited to the sweep provided by the distributor's rotor, I'm wondering if I can't just bump this up to some ridiculously large number like 60. I can post a log, but after looking at what I have there's nothing I see that strikes me as actual detonation. The biggest knock events look like they were reverse traction loss when I downshifted from 5th to 3rd at 65mph (even though the rev matching was pretty darned good).

Edit: Overall it feels and sounds better than I recall from 8+ days ago. Unfortunately I didn't have the opportunity today to lug it hard in 6th gear, but the few instances I got close felt like it was on the bleeding edge of misfire. So I think "on load" spark advance may be close to the limit. I just want to push it as far as is possible so the limits are clearly defined.

[kur4o]

I think I measured the rotor width and it was something like 46* so it is a mechanical limitation. Not sure if there is software limitation too, it will be in the tpu if it have one. You can safely raise the limit and see what happens.

Too much advance needs leaner mixture and very little load on the engine. It is also cam dependent because the one I have don`t like too much at sub 35kp, I also noticed that lt4 calibration also have lower values at these range.

Start with slow increase like 1-2* at a time. I noticed sometimes 1 degree makes the difference.
Zero throttle coast down must be matched with the main table so you don`t feel jerking when you left the throttle. It also greatly affects fuel economy.

When you are finished the fueling might need revision too.

I am still waiting on the caps and will be more than happy if we figure the coil sticking problem since then. At least I will not be much worried of coil`s ignitor melting.

I will try to pick inductive signal from stock coil plug wire[coil to cap] with visual identification, so we can match it with the sticking coil, Or you can add some debug logging of est signal state.

[spfautsch]

You can safely raise the limit and see what happens.

Planning to drive it Friday with it set at 58. Hopefully there's nothing in the TPU that will screw with me...

Too much advance needs leaner mixture and very little load on the engine. It is also cam dependent

Mine has 50+ degrees of overlap, so it's like having the EGR valve stuck open below 2000 rpm. More EGR means less dense mixture that burns slower and wants more advance to hit peak cylinder pressure at 12-15 atdc. Judging from the sound difference at part throttle, it likes it.

Start with slow increase like 1-2* at a time. I noticed sometimes 1 degree makes the difference.

I'd taken a few degrees out of the stock tables in most areas after the initial build with the cam and roller rockers. But I had ridiculous amounts of false knock until going to the shaft mount rockers so never worked further on timing. Now that I can (generally) trust the knock sensors I'm going to push a couple degrees at a time until I see something happen. I have all forged internals now so not too worried about a little real knock.

I'm attaching the bin - the cells that are hitting 46-48* advance target are all below 45 kpa with the car in motion. It idles at 43-48 kpa, so these are all in the "hump" right before DFCO kicks in.

Ideally I would get it on a dyno to find MBT, but I've yet to find anyone with a load cell setup.

Zero throttle coast down must be matched with the main table so you don`t feel jerking when you left the throttle.

Thanks for the suggestion - I didn't even know there was such a table. This could explain my parking lot bucking issue. Would you know the address offhand?

... will be more than happy if we figure the coil sticking problem since then. At least I will not be much worried of coil`s ignitor melting.

I have a new board 70% built and plan to finish it this weekend to test this. But if it's only happening during initial cranking it's not a problem I'm going to lose sleep over.

And you're not going to be melting anything. For the umpteenth time, the coils have built-in dwell limiting. You can dwell the m.f.ers 24x7 for days and not hurt them.

I will try to pick inductive signal from stock coil plug wire[coil to cap] with visual identification, so we can match it with the sticking coil, Or you can add some debug logging of est signal state.

I wouldn't get too crazy worrying about the sticking coils, unless they're sticking after an additional full engine revolution.

However, if you have access to an oscilloscope I'd love to know what (if any) time difference there is between the distributor coil firing, and the COP coil. A couple of inductive pickups on plug wires would handle this. You're not going to be able to see it with 60 fps video - it's going to be on the order of a few hundred microseconds or less (0.0001s being 100 microseconds).

[NomakeWan]

Thanks for the suggestion - I didn't even know there was such a table. This could explain my parking lot bucking issue. Would you know the address offhand?

Maybe this? http://fbodytech.com/tutorials/fix-l...e-stall-saver/

Even on my stock car, it made stop-and-go traffic far less jerky. If it's not that, I'm not sure what it would be.

[Terminal_Crazy]

Note:
The tables & descriptions vary depending on whos XDF you use

Steveo's XDF describes these as Stall saver.
Kur4o's XDF describes these as Coast Spark & lists the tables differently to Steveo's

Thanks
Mitch