Buggy Buggy and more Buggy

I am started this post with the name Buggy Buggy Vroom in the optimistic expectation that it would end with the first motor startup. So far, it's just been Buggy Buggy and more Buggy.

The first bug I ran into was an interesting one. Flipped the main power switch and the starter immediately began cranking. And the only way the starter would stop cranking was if I pressed the starter button. This is not how I intended the starter button to work. Turns out I accidentally ordered a momentary OFF button instead of momentary ON.

Fortunately this was an easy fix: the momentary on and momentary off switches are the exact same parts, only with the cover reversed. Middle picture is momentary off. Right side picture is momentary on. 

Next I discovered that several of my circuits didn't have power. Multimeter to the fuse box demonstrated that about half of the fuses had no power supplied to them.

The drop down electrics panel I made is very accessible for maintenance eg, changing a fuse or hooking up a laptop to the ecu, but awkward if, by some crazy turn of events you have to dismount the fuse box.

Above: I neglected to use riv-nuts or captive screws, so I had to get my daughter The Bear (small, agile) to crawl under the dash to get a person on the nut side and another person on the bolt side.

Once I got the fuse box dismounted I saw a lead that had gotten tucked under the fuse box and never connected to anything. Now, I am not an electrical engineer, but it seems plausible that a wire with one end dangling in space not connected to anything might not provide the desired power on the other end.

More Buggy Buggy Buggy

There has been a bit of a time lapse since my last post above. I connected the un-fed power feed and then suddenly ran in to another problem. No power to anything anywhere. I went hunting with the multimeter and found that there was 13ish volts at the battery, 13ish volts on the input to the main breaker, and 13ish volts on the output of the main breaker. There was also power to the main relay power feed and the main relay trigger wire. The main relay had ground and there was continuity from the main relay output to the power distribution bar. I bench tested the main relay and it worked. But there was no power at the power distribution bar.

This is the face I make when there's power at A, B, and C. There's a good connection between C and D. But no power at D. I struggled trying to figure this out for 11 days. Then my brother Uncle Ray the Engineer had a free half day and came over, to figure out the problem in 11 minutes. Upshot:the main breaker was defective.

The Culprit

I had tested to check there was 13.5 v coming out of the breaker - but Ray noticed it was 13.8 v going in. Ran some checks, and it turns out, as soon as you apply any load at all, the post breaker voltage drops below 2. We used an inline 15A fuse to bridge across the breaker and suddenly everything works.

 

The orange-ish light to the left of the tach is the warning light that used to be labelled "GEN" on old cars: the one that tells you the car is turned on but the battery is not being recharged. Maybe you just didn't start the motor yet. Or, maybe your alternator is bad.

Well, "everything works" is probably an exaggeration. But certainly a lot of things that heretofore didn't work now do work. I can't figure out how they made a breaker malfunction like this one did, but at least I know where the problem is.

First Contact

So next up is the startup procedure with my Microsquirt ECU, and the first next step was to get my laptop and my ECU to establish diplomatic relations.

Note the absence of a "No Connection" warning in the middle of the screen.

I did calibrate the sensors, which was fairly easy because Tuner Studio (the laptop app that I'm using to program my ECU) already had the resistance curves for the coolant temp, MAP, and IAT sensors I am using. Calibrating the throttle position sensor was as easy as toggling "record current" with the throttle completely closed and again with the throttle completely open.

Next in order is entering roughly 10,000 values to tell the ECU what it's looking for and the targets it should be aiming for. Some of these are single-answer variables, like maximum spark duration and injector latency time. Some are tables of data, like the desired air-fuel mixture at a given temperature and RPM. Tuner Studio has default values for all of these - some of which are probably close enough to use as starting points. Some of these are specific to the Miata engine, like "fuel injection: batch" and "ignition mode: wasted spark." So I've been going through and trying to find values for as many of these as I can.

All of this is working toward the first attempt to start the engine. I started out getting lost in granular details, then realized what I really needed was a broad overview of ECU programming. I hunted through YouTube trying to find something on this topic and doh! realized I'd already seen the exact video I was looking for on SuperfastMatt's YouTube channel. I first found this channel when I was looking for general wiring tips and one of his videos nudged me in the direction of using a Microsquirt ECU. There was a second video where he went into the details of programming the ECU. At the time, Past Me decided this would be more helpful to watch later, when I was actually in the process, but for some reason Past Me didn't communicate with Present Me about it. Gee, thanks, Past Me.

Simplifying by Adding Complexity

The more I dug in to the ECU programming process the more I realized that a lot of the data I was looking for can be collected and communicated to the ECU directly by a wideband O2 sensor and wideband controller. Until now I'd been thinking wideband was an extra complexity I didn't really need. But then it gradually dawned on me that letting the engine fill in the ECU data itself was in fact simpler than me trying to locate/estimate/calculate the data and entering it myself. So wideband it is. The people who make Megasquirt and Microsquirt like this one:

The wideband sensor itself is just a chunky thing you screw into a threaded bung in the exhaust system, so that's not terribly complicated. But it also needs a controller (the black box above) which is another electronic component that has to be installed.

Mistake + Mistake = Clever Foresight

One of the things up to now discouraging me from adding wideband was the need to run new power and ground lines all the way back to the battery + and - terminals. The first thing I did when wiring the car was assemble a bundle for all the wires that have to run from the cockpit/engine compartment back to the boot/trunk and thence to thither. I figured I'd probably forget something so I put in an extra wire and labelled it 'spare.' But the wideband controller needs two back-to-front wires, so I was faced with the prospect of trying to add another wire into the front-back bundle (an extremely annoying if not impossible job). Then I looked at the end of the bundle and realized I actually have two spares. When planning the front-back bundle, I accidentally put in two wires for main relay trigger and gave them two different names. This caused some confusion until I figured out what I'd done. What I had in fact done was provided myself with two spare back to front wires. Thus all wiring I need for the broadband controller is already there, just waiting for me. It's a rare example of two mistakes cancelling each other out in such a way as to produce the same outcome as if I'd thought this all out ahead of time.

Exhaust Diversion

I had to pull the exhaust down tube out of the car to weld in a new bung for the wideband sensor. This sensor is really picky about where it's located in the system and I didn't have a sensor bung in that spot. Then once I had the exhaust system taken apart, I was unwilling to put it all back together without finishing up a bunch of little issues here and there that would have to be done sooner or later anyway. I hate putting things together when I know I'm going to have to take them apart again. So instead of trying to start the car, I've been chasing down unfinished exhaust system details.

Upper Left: the tailpipe was coming out at the wrong angle so I had to cut it off the muffler, rotate, and weld it back on. That MIG splatter is from the factory, by the way, not my contribution. Upper right: the factory hangers on the exhaust pipes needed slight tweaking: this one had to be cut off and welded back a bit shorter. Lower left: I spent a lot of time making the chassis side hangers from donor car leftovers and angle stock. Yeah, I know, I could have bought new universal exhaust hangers cheap and been done already. Lower right: the angle under the tunnel isn't exactly 90 degrees, so I had to heat up the angle stock and bend it a little. Should have the exhaust all installed and done tomorrow, Lord willin' and the crick don't rise, and be back working toward first engine start.

Upper left: chassis punch, one of my favorite tools ever. Makes the neatest holes in sheet metal, perfectly round, precisely sized, never needing any deburring (as seen upper right). The only problem with chassis punches is that you need a hand on both sides. Fortunately I had the assistance of my lovely and long-suffering wife for this one. Lower left: I could not find a grommet with OD to fill a hole large enough to pass the plug, ID small enough to close around the cable, and two piece; thus allowing installation on a finished cable with plugs on both ends. So I designed this on Solidworks and 3d printed it. Lower right: Wideband O2 sensor cable coming through the trans tunnel cover all neat and finished.

Above left: I don't know why Mazda put two exhaust hangers so close together but they probably had a reason so I followed their lead. On the OEM Miata system, the hanger in the foreground was on the other side of the car but this wasn't going to work well on my Ill Advised Project Car so I cut it off and welded it on the opposite side. Believe it or not, the OEM Mazda set up was not any less hokey-kludged looking than this. Above right: the pipe coming out of the muffler originally went straight back, which would have run in to the bodywork - hence the need to cut, rotate, and re-weld. Although I just realized I could have put this back together with couplers. But unnecessary welding is the whole reason I got a TIG machine in the first place. The tailpipe is now a little bit too low and probably too long, but there is plenty of extra material to trim it back. I am going to hold off on this final tweaking until I start fitting the bodywork

More $%@#@*ing Buggy

I need engineering notation to express the level of frustration of the past two weeks. I was ready to get into the startup procedure and found that my ECU and my laptop are no longer on speaking terms. Tried a different laptop. Tried a different serial adapter. Tried every single troubleshooting step from every forum and Facebook group plus tech support from the tuner software people and the ECU people and nothing works.

I do have photographic documentation that this thing did previously work (see above)

I just emailed the ECU tech support people asking to send the unit back for testing or exchange. Also I ordered their actual serial adapter and cable (I lost the one that came with the ECU) so maybe that is the fix. I am kind of stuck here because I really do want to get the engine running and make a test drive to be sure everything works before I start in on the bodywork.

Argh x 10⁹⁹