codrus

So Saturday was the actual open house, spent the day hanging out at the shop talking to people and listening to presentations from the FM staff about various things. Keith weighed their ND:



Sunday morning is the end of the event, so load the car up on the trailer and head out. I took 80 through Reno & SLC on the way out, but on the way back I'm stopping in Las Vegas to meet up with Peggy and the kids.



I ran into a thunderstorm in Utah. That and the overcast skies made for nice temperatures for the first half of the trip.



Then the sun came out and it was 100+ instead of 65.

I drove past Cedar City and thought about dropping in to see if Jeff's bakery was open today, but I was running behind so I didn't.



It took 2 hours to go the 20 or so miles of the 15 that are in Arizona, because they had it down to one lane for a couple of miles and there was an enormous backup of cars trying to funnel into it. Gee thanks, AZ.

I was a little concerned that I might have damaged the head gasket on the truck when I drove it into GJ with a leaking water pump, but it behaved itself on the way here, so fingers crossed for the remainder of the trip home!

--Ian

codrus

Hm, it's been a month since I posted here.

350 hp lying on the floor:



Man the car is slow like this:



Good news is that the horsepower can go back in now!

I picked up another catch can for the PCV valve and a set of the LS3 coils with FM's bracket. Let's see if it'll do a 350rwhp dyno before Laguna...

--Ian

patsmx5

iTrader: (16)

I feel your pain! Had to do the same to pass emissions back in april. HOPING I can get my setup built to where it will pass emissions all the time before April of 2016, otherwise I gotta do what you just went through!

Also, badass on the power, that's good, I know that thing is fun to drive.

And your question on VE dropping that much causing the rich condition- yes. Turbo is working at a higher PR to deliver the same boost level, so lb/min drops at any given boost level.

HHammerly

iTrader: (3)

Who makes your muffler? How loud is it? I really like it better than my 90 right + 180 left setup.

codrus

That's the FM 3" exhaust. It's noticeably louder than stock, but not obnoxious.

--Ian

codrus

All the go-fast bits are back where they belong. Alas, the test-drive only went about 50 feet, the exhaust is banging on the chassis so I need to go in and loosen all the bolts, wiggle it around, then tighten it back up again.



Also installed FM's LS3 coil kit:




I could only find MS2 settings for these coils, and it looks like MS3 dwell settings are done in a different model so I had to try to convert it. Anyone else done this?

Here's what I would up with:




--Ian

patsmx5

iTrader: (16)

Wow, can those coils really handle 5.6ms of dwell all the time?

codrus

The MS2 writeup I found for them specifies 5.6 ms nominal dwell, so... I dunno?

Megasquirt Sequencer Coils

--Ian

codrus

So we fixed the exhaust not to bang, took it out for a test drive. Unfortunately, it turns out that using the FM LS3 coil bracket with on my 99, the #1 coil wire winds up being right next to the bracket for the cruise control cable support. It cleared in the garage, but then we took it out for a drive and when boosting onto the motor shifted, the bracket abraded through the plug wire, and it started shorting to the hardline for the brake booster. Oops. Limped it off the freeway, diagnosed the problem, unplugged that coil, set the deadtime on cylinder #1 to zero to minimize how much fuel would get injected, and limped it home on 3 cylinders.

I tried cutting the CC support bracket off the hard line but I'm still unhappy with the way it goes together, so I'm probably going to take the booster hardline out entirely and replace it with a hose. I wrapped the coil boot on the plug wire in electrical tape and it seems to idle properly now, but it'll need replacing before it goes to the track. Fortunately there are still 2 weeks til Laguna.

Anyone know of a FLAPS-available plug wire that fits an LS3 coil at one end and a Miata spark plug at the other? I'll order a replacement from FM, but that'll take at least a few days to get here.

Meanwhile, we stuck a big-*** resistor into the circuit for the coil and checked the saturation time.



This was with the coil seeing about 10.5 volts (12.5 volts off the battery with the car off and the MS3 in coil test mode, minus 2 volts for the drop across the resistor we were using to check the current). Looks like at that voltage it needs around 7 ms to saturate. Checking it at a higher voltage needs a power supply I don't have.

GM uses a big 3d map to set the dwell on the LS3, ranging from 0 to 32 volts on one axis and 0 to 8000 RPM on the other. Anyone know why they vary the dwell with RPM? At 1000 RPM the dwell is roughly double what it is at 7000, and I don't understand why. It doesn't look like the GM map even gets close to saturating the LS3 coils, although presumably a naturally aspirated engine is easier to set off than one running 24 psi of boost, so that's not necessarily an indication of how much I should run.

--Ian

patsmx5

iTrader: (16)

To answer your question, the reason they run more dwell at idle vs at redline is two fold.

1. They can safely do so at idle since overall, the duty cycle is low.

2. The longer dwell gives a longer spark duration. This improves things such as idle quality, lighting off a lean mixture (lean tip in, dirty injector, etc) can run a leaner AFR without misfire.

I run a set of coils just as hot as those, and I tested it and at .040" spark plug gap, with 23 PSI, I had to run 5.5ms of dwell to get it to fire off in boost without a problem (tested 3.0 to 6.0 in .5 increments). This was at 13.7V, 10 guage wires going to the coils, etc. I rev to 8,500, so this was way too much duty cycle for my street car reliability standards.

My final solution was to drop the spark plug gap to .030". I now run 3.0ms across the board and have no problem lighting it off. In fact I tested 2.5ms and it ran just fine, but 3.0 is very safe so I left it there.

Downsides to less gap that I noticed are idle quality and lean mixture light off. With .030" gap I misfire around 17.5:1. With .040" gap I could idle at 19.5:1 without a misfire! Needless to say things like lean tip in stumble disappeared with the higher gap.

patsmx5

iTrader: (16)

For your plug wire, you could go buy a chevy wire and use long neck needle nose wires to snap it onto the plug. Or strip/splice the spark plug wire that was damaged and then put about 20 layers of electrical tape over it. I think 1 wrap is 600V or so of supression, you'll need 25kV-40kV of suppression depending on your spark plug gap.

williams805

iTrader: (2)

That looks like a current ramp for the coil to me. If so, I'd say you can shorten the dwell a bit and still get the same fire out of it. See how it levels off at the bottom for a while? That means the coil is fully saturated. It's not getting any more full. I'd set it so that it levels off for half that time or slightly less. No need for anymore, it's just creating more heat. Basically as long as it hits whatever that peak current is before it fires, you're getting max energy out of it.

Also I'm used to looking at these with the ramp going up. Just the way I learn I guess, but if you flip the current probe over it will ramp up instead of down. (Nitpicking I know).

aidandj

iTrader: (5)

<p></p><p>Ugh, not tektronix no care. Get a better scope.</p><p></p>

codrus

It's the current measured by looking at voltage drop across the shunt resistor, which is why it's upside down. Yes, I could flip it if I ran it again. This was using the MS3's test mode, I was deliberately driving it into saturation in order to more easily measure the saturation point, I don't plan to run it at the saturation level. The GM map for 10 volts (which is about what the coil was seeing at that point) never uses more than 6 ms, and is only over 5 below 2500.

Lighting off a leaner mixture makes sense, I could easily believe that GM wants to run it leaner at low RPMs to improve fuel economy.

--Ian

codrus

This one was free!

--Ian

aidandj

iTrader: (5)

<p>Probably the only acceptable response :P</p>

EO2K

iTrader: (37)

You are the one with the cart o' o'scopes, y u no hook a bother up?

aidandj

iTrader: (5)

<p>Would if I could. All the ones I have access to are prototype non-saleable units.</p>

EO2K

iTrader: (37)

So don't sell them?

I've wanted a scope for years. So many jelly over here, if you couldn't tell.

aidandj

iTrader: (5)

<p>I don't think that what it means exactly </p>