Electrical - What Was That About Achille's Heel?

 I've made a few speeches where I brag about finally learning electrical engineering (being a BSME) due to the changes in the industry, which include eMobility and mechatronic actuators.  It's not a lie to say that I know more than I did 10 years ago but it's also truthful to say that I still suck at anything electrical!  In the mechanical world, if you make a working prototype, you are around 75% representative of high volume production.  In the electrical and software world, a working prototype is something like 10% of the way toward a production solution.  This is even worse when wiring a 55 year old car to talk to a 10 year old Engine Control Unit (ECU).

So, bad things happened.  The good news is my ECU supplier was very supportive.  The bad news is, it costs $180 to ship the 2.8lb ECU you blew up through your ignorance to them and basically costs you the summer of driving in Ohio's few weeks of pleasant weather!

For example, if you connect 12V to a transistor which is expecting ground, the connector blows up.

For example, if you haven't found this picture before you start wiring, you might think you are looking at the front of the connector but, in fact, you are looking at the back.  This will naturally cause you to connect the wires backwards which will put 12V on the air temperature sensor pin which is designed for 5V.  This will the cause you to put your ECU in a box and send it back down under for service.

For $180!!

I am happy to have learned decent connector crimping skills and very proud to have discovered on-line sources for connectors I thought I would have to cut out of an RX-8 in a junkyard.  That was my first approach and, after calling about 20 local junkyards, I found one with an RX-8 in the yard.  The manager was happy to receive me and sent me to their secondary yard where I hopefully climbed out of my Explorer, tool box in hand.

I then met the proprietor of the secondary yard.  As I approached, he hitched up his jeans about 3 inches, still leaving a solid inch of hairy crack above the waistline.  I inquired as to the location of the RX-8.  He asked what I needed and I replied some connectors, MAF, and accelerator pedal connector.  He laughed out loud.

He said "She was in a front end wreck.  I had to drag the engine out from under the seats.  It's hangin' on a chain there.  Block is busted.  Can't even be rebuilt.  But you're welcome to take a look."

So, I carefully jumped from dry spot to dry spot, as all junkyards are half marsh, until I finally found the remaining carcass of the RX-8.  A lump climbed up my throat, partly from disappointment and partly from the prominent biohazard sticker on the driver's side door.  The car was worse than he had described and there is no way the driver survived.  I took a quick look but nothing I needed was left.  Junkyards are a strange waypoint between death and rebirth (being based on recycling) but the death vibe is usually stronger.  Damn.

I then became thankful for squirrels. 

It seems that squirrels frequently climb under hood and chew apart wires.  Therefore, there is an aftermarket business in connector pigtails.  I was able to find an exact fit for the pedal sensor and the mass airflow sensor.  The ECU plugs 4 and 5 were more difficult. Somehow, by Google searching, I found a plug from a Honda that looked exact for ECU plug #5.  As I was inspecting the picture, I thought I might be able to machine it down to fit #4.  And, in fact, I could!

So, my connector problem was solved without puddle jumping in junkyards.  

It's only 23 wires that need to be wired into the ECU but it looks like a hundred!

Looks nice and professional...except some are connected to 12V instead of ground!

Here's how one works on a car these days!  Two laptops, one for the oscilloscope and one for ECU communication.  For years, I was afraid that new cars would become so complex that a home mechanic wouldn't be able to do any work anymore but human ingenuity prevails!  Today, it's common to exchange your ECU, hack your ECU, retune your injection and ignition maps, etc.  All with relatively cheap tools.  A glance at the first The Fast and the Furious shows this in action.

Hopefully, this spaghetti will soon drive the engine!

Well, my friends in Australia did well with my repair and only charged me $225 including shipping.  In the end, this screw up cost me 5 weeks.  In that time, I did manage some clean up and re-assembly of interior.  Basically, I underestimated this job by even more than most project rules of thumb would suggest!

I spent many hours drafting an actual schematic of how to connect this modern contrivance to this 55 year old roadster.  I had it checked by my BSEE brother.  I also bought pizza and beer for our Schaeffler electrical technician to double check my wiring for errors.  The moment when we finally decided to plug in the ECU was very tense!  But, in the end, an anti-climax.  It powered up fine and we could calibrate the throttle pedal.  We turned the key and she fired right up.  Larry hit the gas and she actually revved up!  Thank goodness!

I confess that I'm not sure how my Australian friends at Adaptronic can make a living at this but I'm thankful that they can!  They must have thousands of hours into reverse engineering these Mazda's and laying out a circuit board, writing the software for the controller itself and the PC interface, plus, setting up a repair service for those of who didn't at first understand which pins can tolerate 12V!

In any case, human ingenuity keeps up with itself, allowing amatuers to work on their own cars in the computer age!  Let's go humans!  And keep having #funwithcars !