Targa Miata
February 20, 2007 - The part that nobody looks forward to.
Before assembly carries on much further, I have to install the wiring. I also have to trim it down so we don't bother carrying around the extra weight of stereo and electric window wiring.
entry 76 - tags: wiring, weight loss
February 25, 2007 - I swore I wasn't going to do this.
But it bugs me to know of all the airbag wiring in the car, and when I came across the rear window defroster and the power antenna connectors I just couldn't help myself. It's sticky work with miles of masking tape involved, but it's also really good to know that a number of useless wires are gone. That not only lightens the car, but makes troubleshooting easier.
The airbag harness is the thick section that's still wrapped up in black loom. It's all out of the car now, and the only other system that is affected is the horn. That's easy to put back.
entry 84 - tags: wiring, weight loss
February 25, 2007 - Mystery box.
I've commented before on the importance of labeling everything as you work on a car.
Edit: Aha! It's the cruise control brain!
entry 85 - tags: wiring, tips
March 7, 2007 - The Hydra Nemesis computer that will control the car is going to be wired in.
It's available as a plug-in installation, but we can get rid of a whole bunch of wire by splicing these plugs right into the harness. The stock ECU is mounted behind the passenger's seat, ours will be under the dashboard.
entry 88 - tags: wiring, engine
March 23, 2007 - It's time to start putting some of the wiring in more permanent positions.
This will at least let me sort out some of the more critical bits such as where to mount the Hydra Nemesis ECU and the Coralba C-Giant rally computer. I'll leave it mostly unwrapped until it's all sorted out though.
entry 101 - tags: wiring
March 31, 2007 - A similar big brake kit is used on the front.
There's a significant weight advantage and the Wilwood calipers make it really easy to change pads.
Hidden behind the rotor is the 44-tooth sensor for the ABS. If we can find enough technical information, we'll use this as a sensor for the Coralba rally computer. Coralba is not being helpful at all - we know exactly what the ABS signal looks like, but they won't tell us the required signal for the computer. Instead, we're told to buy expensive peripherals and patch them into the car instead of using the sensors that Mazda spent a lot of money developing. I want to just plug this one in, figuring that there's not a lot of variation in hall-effect sensors. Eric's not so sure, probably because he's the one who gets to use the computer! If anyone out there knows what sort of voltage range is acceptable as an input for a C-Giant rally computer, let us know!
entry 111 - tags: brakes, wiring, computer
April 2, 2007 - The Hydra Nemesis ECU (engine control unit) along with a selection of brackets.
These brackets are all sold by Flyin' Miata to mount the Hydra in various models of Miata. None of them suit our particular needs. Brandon from FM reworked the top one to fit the ECU to the firewall. I threatened to cut lightening holes in it, he called me a nut. Regardless, the ECU is nicely and firmly mounted out of harm's way.
entry 114 - tags: wiring
April 6, 2007 - Time to start the big wiring job.
A 1994-97 Miata puts the engine computer behind the passenger's seat. This snake of wires is a dedicated harness for the ECU. Since I don't want the ECU back there, nor do I want the weight of the wires, I'm going to modify this harness extensively so that it has the correct plugs on the end for the Hydra Nemesis and also to shorten it for the firewall mounting location.
The original plan was to splice the Nemesis wiring directly into the main harness, but this is a more flexible arrangement if I ever decide to change to a different ECU. I can just unplug my adapter harness and pop in a stock one - or another adapter. It'll also be easier to test the wiring when it's removed from the car like this.
entry 116 - tags: wiring
April 8, 2007 - The wiring harness in the previous picture looked fairly simple, but these little guides and mounting brackets were all taped in to make sure it went where it was supposed to and it was protected.
It's always interesting seeing how a manufacturer deals with something like this. Despite the fact that it's been 13 years since the car was built, the wiring looks almost new.
entry 117 - tags: wiring
April 8, 2007 - Despite the nice clean workbench in the last picture, here's where the work is really getting done.
Why? Because I want to get the wiring lengths right. The three plugs that supply my various signals are in different places, and the three plugs on the ECU are also arranged side by side. So the ideal length of every wire is different. It's not exciting, but it is engrossing work.
So much for my theory that it would be easier to test the harness on the bench.
entry 118 - tags: wiring
April 8, 2007 - This is the wiring saved by moving the ECU to the firewall instead of the rear bulkhead.
It's shockingly heavy, especially when rolled up like this.
Race cars don't need as much wiring as street cars. There's no need for air conditioning or heaters, for example. Our aftermarket ECU also uses some onboard sensors or alternate sensors that use different wiring than the factory unit. Once it was wired in, I traced back all the unused wires from the stock plugs, confirmed that I didn't need them and then cut them out. Yes, it saves a few ounces but that's not the main purpose. The fewer wires there are in the harness, the easier it is to debug any potential problems in the future. Today I pulled out the wiring for the power windows (big fat wires - that was significant), the optional foglights (I'll probably wire in some lights myself in the future, but they'll need better wiring than the factory stuff), the mass air flow sensor (our ECU uses a MAP sensor instead), the diagnosis connector underhood (we can talk directly to the ECU) and a few other bits and pieces that aren't needed. The harness is getting simpler and simpler.
entry 119 - tags: wiring, weight loss
April 9, 2007 - The great wiring exodus continues.
This pile may not look like all that much, but there's probably more wire out of the car now than in. The harness is getting much thinner and easier to work on.
It's amazing how much of a modern car's (assuming a 1994 Miata is considered "modern") wiring is due to the audio system. Between headrest speakers, door speakers and power antennas there's a lot of it snaked around the car. Imagine a car with a premium sound system!
entry 120 - tags: wiring, weight loss
April 22, 2007 - The 1995-05 Miatas had a "fake" oil pressure gauge that basically just showed that there was at least 7 psi of pressure - that's the little sender here.
The 1990-94 Miatas had a more traditional oil pressure gauge that showed actual oil pressure - that's the big grey sender. I want to run both. A real pressure gauge to tell me how things are going, and a big bright turn the engine off NOW! light.
Another camera phone picture, sorry.
entry 145 - tags: engine, interchange, wiring
May 2, 2007 - Part of the fun of building a car like this is deciding where to put all the knobs and switches.
The main cutoff is going to go inside the car somewhere. I was going to put it here on the transmission tunnel, but further experimentation (ie, I pretended to drive the car) showed me that it would be pretty easy to flip open with my elbow. Now that would be an unhappy moment! Now I'm looking at installing it in front of the gear shift. First I need to see if there's clearance underneath.
entry 157 - tags: ergonomics, wiring
May 2, 2007 - More wiring fun.
I have the fuel injector harness sorted out now. All the connections are crimped with a ratcheting tool for a good solid connection, then mechanically secured with heat-shrink. It's important to do this well, as bad connections can obviously cause a real problem in the heat of competition. The collection of crimp connectors is one I've assembled myself from Del City, with the exception of some less-than-stellar ring terminals. Those are mostly used for grounds so there's less concern about shorting out.
entry 158 - tags: wiring
May 3, 2007 - Ahh, more wiring.
It's the job that never really ends. But I feel as if I'm making some progress, as parts are being hooked up and large sections are being called finished.
The final location for the cut-off switch can be seen here. It should be within easy reach for both occupants, but also difficult to flip accidentally. The location works well for the wiring as well - the main line to the battery runs just underneath.
entry 159 - tags: ergonomics, wiring
May 6, 2007 - The subframe brace here is from a 2003 model.
Not only does it stiffen up the rear suspension, but it also protects the differential. It doesn't protect against rocks as well as a legit skid plate would, but I'm more concerned about bottoming out the car on pavement and it should help out there. It also wouldn't be difficult to add a plate or two to this solid frame.
The little skid plate on the red PPF is visible here as well, and the brace does make it rather obsolete when I look at it now. Oh well.
It's also possible to see in this picture that the exhaust system is in place. The main power line running from the battery to the engine bay has been cut and modified so it goes through the cut-off switch, then the wiring was properly secured. The driveshaft is on - and all of a sudden, I have a complete drivetrain!
entry 162 - tags: exhaust, wiring, drivetrain, interchange
May 6, 2007 - I dropped the radiator in to check some clearances.
It's from an automatic car so it has a dual core instead of the truly weedy single core used on the manual cars. It has steel tanks on it instead of the crack-prone plastic ones found on factory rads as well. It is better than an aluminum race radiator? Well, no. But I am trying to build this car out of available parts for a reasonable cost. It's easy to forget that with the recent engine build.
It's close to engine start time. I need to hook up the crank angle sensor and get a lower radiator hose on the car. And then it's a matter of taking a deep breath and putting some electricity through the car. I'm a little nervous about that actually - I don't have as high a level of familiarity with this particular ECU as I'd like, and there are a lot of changes to the wiring. Maybe I'll see if Jeremy from Flyin' Miata wants to drop by for an evening.
entry 165 - tags: interchange, wiring
May 11, 2007 - It's alive!
Well, only in an electrical sense. I ran current through the car last night and no smoke got out, so that's a bit of a success. My battery was pretty low on power so I put it on the charger. The low voltage was causing some odd behavior as various systems would wake up partway but not all the way - for example, the hazard lights kept trying to come on.
This morning, I checked again. Brake lights, good. Turn indicators, good. Functioning oil pressure gauge (tested by grounding out the signal wire), good. Headlights...well, I'll have to look at that one later. Power to the fuel pump and ECU, good. I didn't fire the car up because there's no oil in the engine, so those tests will come along in the next few days.
I'm a little nervous about it, to be honest. This car is such an odd collection of bits, and even the sensors on the engine are put together out of several model years and patched together with software. Will it work? Of course it will, eventually. But that doesn't prevent me from imagining terrible things.
entry 168 - tags: wiring
May 12, 2007 - There's juice in the battery and the lights in the rear are working!
Okay, it's nothing like the sort of victory of finally firing up the engine, but it's still gratifying to have the car actually respond to a request. I'm hoping for first noise tomorrow, let's see if that happens!
entry 172 - tags: wiring
May 14, 2007 - More testing, and it's getting closer.
Brandon and I started firing up one system after another tonight, but when it came time to talk to the ECU we had difficulties. It was finally tracked down to a blown fuel injection fuse.
This particular fuse feeds a whole lot more than fuel injection. It's the one that supplies power to the main relay, and is the primary source of switched power in the car. So we started by disconnecting everything and powering up one system at a time to see if the fuse would go again. Nope. Everything came back online and we were able to communicate with the ECU - until Brandon unplugged the idle speed control solenoid and pop! the fuse went again. Playing with the intake tube seemed to cause a momentary problem once the fuse was replaced again.
We did a little more poking around and found a bare wire that had been grounding out at the block when the intake moved it slightly. Whoops! The wire was trimmed back and insulated and everything was good again. All sensors indicated reasonable numbers, so we decided to go for a start. We pulled the fuel injection fuse (the fourth one of the evening by this point) so we could crank the engine over to get the oil pressure up.
Except that the freshly charged battery didn't have the guts to turn over the 11.5:1 engine. Neither did any of the other freshly charged batteries scattered around the shop.
The moral? It's time to get rid of all those batteries I'm saving because they might still be good! They're not. It's time to go get a known good battery for this car and stop screwing around.
So that was it for the night. Tomorrow, I return with a fresh, powerful battery and we make this engine spin!
entry 173 - tags: wiring
May 15, 2007 - In order to exorcise my battery woes, I brought home a collection.
The largest is an original equipment Panasonic AGM, much sought-after by many Miata enthusiasts. The middle size is the standard Mazda "High Performance" replacement. The small one is the killer Odyssey PC680. Similar power to the others, but half the size and weight. The latter is what I use in the Seven and this particular new one was stolen from my boss' Westfield "to be installed" pile. I wouldn't mind running a PC680 if only due to the weight, but today it was the mid-size Mazda replacement that was put to work.
entry 174 - tags: wiring, interchange, weight loss
May 15, 2007 - It's alive!
The car runs!
The trouble light shown here is being used as an oil pressure light to back up the gauge. The fuel injector fuse is removed so I can crank the engine (that poor little battery) and get pressure up. The test light went out at 7 psi and the analog gauge woke up shortly after.
Once oil pressure had been established, I powered up the ECU and connected the laptop to make sure all the sensors were sensing appropriately. A turn of the key and a bit of cranking as the fuel system filled - and then boom! The engine came to life. There's an exhaust leak somewhere (maybe I forgot to install something), but the engine revs sweetly. I only ran it for a few seconds before shutting down. I have a few other things to attend to right now (such as my wedding on Sunday), but a major milestone has been reached. There was much rejoicing!
entry 175 - tags: wiring, tuning
June 13, 2007 - I did a bit of cleanup on the wiring and stuffed the dash in the car.
The dash isn't removable with the windshield in place thanks to the cage and the welded-in structure. So it would be best if I had all the wiring sorted out or at least well wrapped and secured before the dash was attached.
I expect I'll have the dash out again soon, but it feels really good to have it in there!
entry 205 - tags: wiring, weight loss
October 7, 2007 - Miscellaneous work this weekend.
I installed the Revlight tachometer to the top of the instrument cluster. I really like these little guys, it's a shame they're out of production. A bright LED was added to the front of the cluster cover as well for a low oil indication. Yes, I have a proper gauge, but in the heat of competition a bright red TURN THE ENGINE OFF NOW! light is good. I have video of a driver on the track with all the unwatched gauges screaming danger as the engine destroyed itself. A big red light would have saved us a lot of work in the pits the next day as we had to install the new engine...
Anyhow, in the process of installing the oil light, I managed to crack the 16-year-old plastic of the instrument cover. This was after gluing the mounting brackets back on. Maybe it's time for a new one.
Meanwhile, Brandon did a bit of work on the driver's footrest. I also managed to get most of the parts for the VICS (a variable intake setup) fixed up and ready to install. This will add a bit of top-end power.
entry 322 - tags: ergonomics, engine, wiring
December 5, 2007 - I fabricated a plate to cover the missing center console cutout and give me a place to mount some switches.
Of course, I counted the switches I needed, came up with four and then carefully drilled 5 holes. Nice work. That's okay, I'm sure something will come up that needs an extra switch. The one under the guard is for the wiring for auxiliary lights. I don't expect to have them installed very often and I'd prefer not to accidentally turn them on. Of course, that's just a justification for using the cool guard.
Finally, some work that isn't suspension!
entry 344 - tags: ergonomics, wiring
December 5, 2007 - Since the switch panel stood a bit proud of the dash surface, I wanted to try to make it integrate a bit.
So I curled the edges back. I'd love to take credit for mad metal shaping skills, but really I just bent the lip with a set of pliers and a vise, then did a little extra forming with a body hammer. A grinding wheel cleaned up the edges and a wire wheel gave it a nice sheen. I might paint it black, but it looks pretty good au naturel.
In other news, I ordered the bilge blower for the defrosting system today. First I visited a local boating store, where I had a hard time communicating that I needed a bilge blower and not a bilge pump. They were completely unhelpful, so Amazon came to the rescue. Maybe I'll set it up so it acts as an electric supercharger when I don't need the windshield defrosted!
entry 345 - tags: ergonomics, wiring
December 10, 2007 - Ah, a 3-day weekend with no plans.
Time for a whole lot of work on the car, right?
Well, I did get the navigator's footrest installed. This is the one that was donated by Jason over on the Grassroots Motorsports forum. Thanks again, Jason! My original design for the bracket was made of steel tube. I took a second look before starting up the welder, and realized I could do better. The rear support is aluminum angle, putting the strength where I need it. The side brackets have a couple of holes so I can adjust the angle of the footrest, remove the whole thing or simply lower the main plate to get access to whatever's behind it. It's nice and solid and probably 1/4 the weight of the original plan. I'm pretty happy with this.
I also discovered that the switch for raising and lowering the headlights is double-throw, so I've ordered a few switches to allow me to wire the car properly and this has put off the installation of the switch panel. I've also been doing some research into header collectors, more on that later.
So, what else got done? Well, the master bedroom in the house has been repainted. Didn't see that coming, did you?
entry 347 - tags: ergonomics, wiring
December 15, 2007 - An electric supercharger has arrived for the car.
Well, it would be an electric supercharger if it were being sold on eBay, anyhow. For me, it's a bilge blower that moves about 240 cfm. Perfect for defogging a windshield. The SPDT switches I need to finish up the switch panel also arrived.
entry 348 - tags: ergonomics, wiring
December 15, 2007 - After a bit of crawling around, the switches are installed.
And labelled, of course. The "eject" switch is for Eric if he gets too nervous.
Almost out of sight is the bilge blower. It's been mounted in the footwell under the new Sparco footrest. The plumbing worked fairly well (you can see a bit of it in the picture) and there's a distinct breeze coming up the surface of the glass. This is the time of year to test it, too - next time it rains (instead of snow) I'm going to get all wet and try to fog up the car.
entry 349 - tags: ergonomics, wiring
January 26, 2008 - I made a comment a while back about accounting for the weight of the rally computer.
Well, it arrived from Eric a couple of days ago and there's not really a whole lot of grounds for concern. It's tiny! It's a Coralba C-Giant, although it's also quite possibly the least accurately named piece of electronics I've seen for a while.
entry 390 - tags: wiring, weight loss, computer
February 12, 2008 - While rooting through the Coralba instructions last night, I got inspired to revisit my plan to use front wheel ABS sensors as triggers for road speed.
I've fired off a technical question to Coralba to see if they can answer me, and done a bit of testing on a Miata to see just how the wheel sensor behaves. The biggest potential problem I see is that the Coralba wants no more than 10 pulses per meter. That means about 18 teeth on the trigger wheel - and as you can see in this picture, I have a lot more than that to deal with. I could grind off every second tooth, or maybe two out of three. First, let's see if Coralba responds with any decent technical information.
The fallback position is to read off the speedometer. This will be affected by wheelspin of course, but it's a very simple installation.
entry 402 - tags: wiring, computer
February 13, 2008 - Since I posted the comment about altering the ABS trigger wheel, I've received a number of emails from folks with suggestions.
Unfortunately, trying to find a different way to mount the sensor isn't going to solve my primary problem: how to use the signal. Coralba has told me (in a one-sentence email) that I should use their PGE-V-pres8. There's no record of that unit anywhere on their site or anyone elses that I can find, so I'll see if I can get some information out of a Coralba dealer somewhere.
As for the wheel sensor, Mazda put a lot of effort into mounting that very well for me. It's easy to chop a few teeth off the trigger wheel, much harder to come up with my own mounting that will stand the abuse. So if I can figure out how to set the signal up properly, I will use the factory design.
Adding to the fun is the fact that the wiring harness for my used C-Giant actually comes from another computer. It's missing the wires for the fuel sender (not critical to me, really) and the remote reset (okay, that one matters). I can use the reverse wire as a reset but Janel is really happy about the fact that this unit will count backwards if I have to reverse at all. I'll either have to buy another harness (expensive!) or figure out which of the pins is the remote reset and solder in a new wire.
If it was easy, everyone would do it.
entry 403 - tags: wiring, computer
February 14, 2008 - After a conversation with Pete at P-Sport (a US Coralba dealer) as well as Janel, I suspect I'm simply going to spend the money to solve the rally computer hookup.
Coralba does not share technical information and won't even confirm if my existing harness will work at all. Given that these computers retail for huge amounts of money new, it's probably not worth taking a chance. Janel commented that I should spend my time working on something else instead of reverse-engineering her rally computer.
P-Sport does have both the correct C-Giant harness and the PGE-V-pres8 converter I need to hook the factory Mazda ABS sensors to the Coralba.
entry 404 - tags: wiring, computer
February 15, 2008 - The appropriate Coralba wiring doodad has been ordered so that I can use the factory ABS sensor as a trigger.
But first, I need to lower the resolution. The factory setup sends 44 pulses per wheel revolution. That's about one for every 41mm! The maximum resolution the computer can cope with is one per 100mm. So I ground away 3/4 of the teeth. Problem solved!
entry 407 - tags: wiring, computer
February 27, 2008 - The Coralba, fully installed.
The bracket turned out to be immensely stable, making the computer a solid part of the car. That's good. It also weighs next to nothing, also good.
The computer is partially wired in, enough that I can verify that it's functioning. Good news, the modified ABS wheel sensor appears to be working perfectly. I did a rough calibration using the car's odometer and drove around town pretending I was on a stage. It's a very cool little unit with a lot of capability, and thus it will take a bit of work to understand it properly.
Other than the wheel sensor, I also wired in the reverse signal. This prevents the odometer from adding distance when the car is reversing. I can add a second remote to the computer if this feature is ignored, which can be used to finish a stage and display all the useful information. Hmm, I'll ask Janel which she wants. She was very excited about the reversing feature though. I sure hope she wants to keep it, it took me an hour to splice in one wire due to the position of that wiring harness. Ouch.
entry 417 - tags: ergonomics, wiring, computer
February 29, 2008 - I did a bit of autotuning on the way in to work.
The long way, of course. After looking at the changes, it appears the engine is hungry for all sorts of extra fuel up top. This is excellent, as it implies the engine is making more power. Yay! The car should hit the dyno on Monday and then I'll know a bit more. Jeremy at Flyin' Miata took a look at the maps and massaged them somewhat, so I have a better starting point for more autotuning on the weekend.
I also discovered that the Coralba shuts down when the headlights are on. Interesting. I'll have to trace that one back and find out what's going on. Running lights are fine, it's just the main lights that shut it down.
entry 423 - tags: tuning, wiring, computer
February 29, 2008 - Aha!
The relationship between the rally computer and the headlights is now clear. It started when I went looking for an unswitched power supply for the computer. The last thing I wanted was for me to accidentally reset the computer by turning off the ignition, you see, as then I would have to face the wrath of Janel and the potential of a retaliatory "flat left over crest into rock wall" call further along in a stage. I installed a separate switch for the computer instead. Anyhow, right beside the switch was the headlight retractor switch. It has unswitched power. So I tee'd into that.
Well, it turns out that when the headlights are powered up, the electricity to the retractor switch is cut off. Makes sense, you don't want someone dropping the lights when they're supposed to be up. But this nicely cut the power to the Coralba at the same time. I can't see this in the wiring diagram, but a check with the test light confirmed that's what was going on.
I had a handy wire coiled up behind the dash that was labelled "BATT +". See, I'd been thinking ahead. But it didn't work. I pulled out a wiring diagram and it seemed as if it should. But it wasn't used for anything else. So I checked the fusebox. Aha! A blown fuse. Popping in a new one lit up the wire and it was a simple matter of teasing it out of the harness and rerouting it to the back of my computer switch.
This was one of those examples where doing something else paid off. My brain kept flipping through options until the "retractors don't work when the lights are on" solution came to mind.
entry 424 - tags: wiring, computer
March 21, 2008 - Big work on the car so far this week.
It's on jackstands, waiting for the shocks to come back after a final AFCO checkup. So I spent some time on it last night and wired up the horn. Big job! Actually, more complex than you might think because the steering wheel adapter I have on the car is from...well, I'm not sure what it's from. Definitely not a Miata. So the wiring doesn't fit. Thus I resorted to a coiled phone cord that can wind around the column as I twirl the wheel merrily. Hey, it needed to be done.
entry 438 - tags: wiring
May 16, 2011 - When I first built the car, I stripped out the wiring harness quite a bit.
And since the V8 uses its own standalone harness, I can strip it out even further. Here's what's left of the usual tangle that runs up the passenger's fender: just the wires for the lights. I'll tidy up the bundles when I'm done, but a clean harness is easier to troubleshoot if something goes wrong!
entry 829 - tags: wiring
May 20, 2011 - With the engine in place, it's time for more wiring.
I started to make the small number of connections between the Miata harness and the GM one. This was made a bit more complex by the fact that the GM setup had already been installed in a 2002 Miata so I had to reverse-engineer the modifications - and of course, the harness in the Targa Miata was heavily changed. Still, it's coming together.
entry 833 - tags: Wiring
May 20, 2011 - I'm giving both wiring harnesses a checkup as I install them.
This broken knock sensor wire is a good example of why. The GM harness had been used in Elvis, FM's first V8 Miata and had thus been installed/uninstalled quite a bit over the years.
entry 834 - tags: Wiring
May 25, 2011 - The wiring continues.
I'm getting pretty close, now it's just a matter of identifying the last few wires, replacing a couple of missing connectors and running the wires to the alternator. Then I'll finish anchoring the harnesses in place (I've done a bunch of work in that area already) and start running some current through the car.
I'm pushing to get the car running for a track day on June 4th. I'll have to take a couple of shortcuts such as temporarily hard-wiring the fans, but it's looking very promising.
entry 837 - tags: conversion, wiring
May 27, 2011 - The wiring is getting close!
It doesn't look like a lot of progress, of course. But wiring a car like this is a series of small jobs - hooking up the reverse lockout solenoid, tracing the oil pressure sensor wire through the harness, etc. But it's close!
entry 838 - tags: wiring, conversion
May 27, 2011 - One of the cool things about GM is that just about anything with a part number can be ordered.
Case in point: this plug for the engine coolant temperature sensor. I don't know why it was removed from the harness by a roving parts scavenger, but a call to the local dealer yielded a replacement on the shelf. Try that with a random Mazda connector!
entry 840 - tags: wiring, conversion
May 29, 2011 - More wiring!
I could do it faster, but I'm trying to build a car that will survive a week of stressful days without failing - and if it does, it should fail gracefully and be easy to debug. This means a lot of time looking at how I'm going to do something, seeing if there's a better way besides the initial obvious solution. Sometimes yes, sometimes no.
I wired up the fans yesterday, for example. I needed a good power supply for the second one, as I've learned in the past that these particular fans can pull over 20A each on startup. The usual way is to run a wire with an inline fuse. But there's a spot in the factory fusebox that isn't used on my car - it's for the ABS system. It also happens to be right beside the fuse for the main fan. So I removed the fusebox and pulled the appropriate connector off the bottom. Turns out the wire I needed simply wasn't there, but there was a spot in the connector plug for a spade connector. I pulled one out of an unusued plug and slotted it into place. Now I had a factory-designed 30A power source! I ran that down to a new relay which is triggered off the main fan. It worked out pretty slick. I even used the same wiring colors used by the main fan so that I know that yellow is a fan power wire, for example.
I also identified a fan override wire that will let me kick on the fans manually without waiting for the engine to get up to temp. I have an idea for that one, we'll see if it works out.
I also wired up the driver's side O2 sensor which needed extended wires and tightened up all the exhaust system connections. The car sounds pretty good. The PCM hasn't figured out how to idle yet so the car won't stay running without a bit of attention to the throttle pedal, but that's normal for the GM computer when it's lost power.
The new shocks ands the driveshaft should both arrive on Tuesday, and it's my goal to have the car ready for them when they arrive. It's looking promising.
entry 845 - tags: Wiring, conversion
May 31, 2011 - Visible progress!
I decided the wiring was in good enough shape to install the dash. The harness is still pretty accessible, but it's more awkward of course. It was quite a wrestling match trying to get the dash back in, it's the first time I've tried that while there was a windshield in the car.
The navigator's footrest is in, the defrost system is hooked up, the switches are wired - it's getting closer. There's no functioning speedometer in the car at the moment but with the rally computer that's not a big problem. I'll address that later.
I did realize that my current fan wiring does have a vulnerability - the right fan is completely dependent on the left fan for a trigger. If something goes wrong with the left one, I'll lose both. I know how to wire this so that both fans are independent, but I'll deal with that later.
entry 846 - tags: interior, conversion, wiring
June 6, 2011 - Lots of final details in the last day before going to the track.
Including some more test driving, and a problem is appearing. The car's running oddly, with a lot of hesitation at times. After some poking around with the wiring, I finally got the OBD-II port to work and discovered that neither of the O2 sensors are providing a real signal. They're flatlined at 0.455v. Turns out, that's the same reading you get if the sensors are disconnected.
Some more poking around at wiring and all the connections appear to be good. Bill and I are doing a bunch of research to see what normal O2 wiring readings should be, we're seeing some things that don't quite make sense. For example, it seems the GM computer feeds around 5v down the "high signal" line and 0.455v less down the "low signal" line. Is that right? I'm still trying to determine yes or no.
entry 855 - tags: wiring, conversion
July 19, 2011 - Lots of little jobs on the car.
One of them is running a constant power supply to the engine computer. I have a kill switch that I use to cut all power to the car when it's sitting, partly to make it easier to work on and partly to ensure no current draw. Well, the GM computer forgets how to make the engine idle every time it loses power, leading to a cranky engine on restart. So I've run a single wire from the battery to the computer in order to keep its memory. It's a very small draw, not enough to tickle the big Optima battery.
I also spent some time tuning the car this morning. Or more accurately, I spent some time learning the ins and outs of the tuning techniques. I'll make some changes to the computer program tonight. Overall, the car's pretty happy and I've been underestimating the amount of power on tap. I think the very well developed chassis is handling the power so well that it's disguising just how potent the car is.
The intake temperatures were better, but still could be lower. I tried popping one headlight up by a few inches and the temperatures dropped significantly at speed - down to maybe 10F over ambient. So it looks as if a bit more ducting would be beneficial.
entry 881 - tags: wiring, tuning
August 18, 2011 - Not all the work on the Targa car is big cool projects like skid plates.
It's also getting some maintenance. For one, I'm changing out the front hubs to make sure they're at full strength. The current hubs had a total of about 10,000 miles on them but a large proportion of that was with hot race rubber bolted on. And, just like the original build, I had to grind off 75% of the teeth on the ABS trigger wheel in order to drop the number of pulses per mile to a reasonable number. The ABS sensor is used to trigger my Coralba rally computer, and it can only deal with 16,000 pulses per mile or so. With the modified ABS wheels, I get about 9,900.
And then I found a problem. The replacement hubs have an ABS ring that's about 2 mm smaller in diameter than the stock part. This meant the air gap to the non-adjustable pickup was too big, and it wasn't triggering the rally computer. That's not good. Luckily, the rings are just pressed on so I pulled off the old stock one and put it on the new hub. If only I'd noticed that before I spent all that time grinding!
entry 914 - tags: hubs, wiring, computer
January 9, 2013 - The Targa Miata is confined to the garage by snow at the moment, but I'm using the time to work on a number of aspects.
First, I'm installing the track suspension and doing some maintenance on the AFCOs. I'm also changing out the hood pins for Aerocatches so it's easier to open and close, and a pair of hydraulic rams have taken the place of the hood prop to improve access underhood.
I've also got some electrical parts to install. The big one? Two big burly relays to replace the factory one that cost us the lead at Targa last year. They'll be installed in parallel so I have some redundancy in case one goes out, and I might add some warning lights so I know if one has failed. I'm seriously considering the wiring on the car, it's showing the signs of the car's gradual evolution and it might be time for a complete rethink. There are also a few areas where I've been relying on Miata reliability to keep me out of trouble, perhaps more redundancy would be smarter. Twin fuel pumps and filters, maybe? Given the Newfoundland gas, that's not a terrible idea.
I've also got some power windows to install. Way back in the original build, I decided the manual windows were a good way to save one pound per door. But with the current cage configuration, we can't actually adjust them with the doors closed. Janel and I both became fairly blasé about popping the door open on the highway to wind the windows up and down, but it sure would be a lot easier to simply hit a switch. It would definitely attract less attention.
entry 1067 - tags: wiring, suspension, plans
November 11, 2013 - Future failure avoidance.
Prior to installing the engine, I spent a fair bit of time going over the wiring harness and ensuring it was well restrained but accessible. In a couple of spots, I was unable to avoid wires making contact with the block. In those places, I made sure the wires were protected. They're not quite in contact, but with all the vibration to come they need something.
entry 1110 - tags: engine, 6.2, wiring
November 13, 2013 - Because the Targa Miata has a stripped out interior and no HVAC system, I've got some space that's not usually available on the street cars.
I've decided to mount the engine computer to the interior side of the firewall so it'll stay a bit cooler than being underhood. This means I have to pass some significant cables and connectors through the firewall. I don't have any wire grommets that size.
This panel is the answer. It has a clip on the backside to lock the bottom into place and the top is bolted down - it's upside down here. The wires are all centered in the grommet before the second half is riveted in place.
entry 1112 - tags: engine, 6.2, wiring
November 13, 2013 - Wiring fun!
This poor car has been through a lot. I stripped out the harness when I built it, and modified it for my purposes. When the original V8 conversion was done, the engine wiring came from a 2002 Firebird - but had already been installed in another Miata. Then I kept modifying and tweaking things, changing the harness around further. Wires for electric windows, cameras, dataloggers, extra sensors, goofy rear wings and the like. It's a bit of a mess.
With the new engine, I'm installing a standalone engine computer and wiring harness. I'm taking this opportunity to revisit all the wiring in the car, removing the leftover bits from the four cylinder build and that junkyard GM stuff. This under-dash harness will be greatly simplified, and the whole thing should be much more robust when I'm done.
It sure looks horrific when it's unwrapped and spread out! The junkyard GM parts are still wired in, and the new GM wires are also looped around like snakes in this shot. Fun stuff.
entry 1113 - tags: engine, 6.2, wiring
November 25, 2013 - Progress!
After hours of tracing wires, the harness is getting slimmer and more robust. It's pretty entertaining seeing the convoluted path taken by some of these. I've removed several big connectors and just streamlined the harness overall. The Coralba rally computer and Peltor intercom wiring is better now. It'll be a lot easier to maintain this setup. It still looks a bit frightening because the harness is unwrapped, but it will be all tied up and secured before the dash cover goes back on.
entry 1114 - tags: engine, 6.2, wiring
November 25, 2013 - Here's the real progress.
That's the Miata fusebox in stripped-down mode. What's missing? The main relay! Yes, the relay that failed and cost us the win at Targa Newfoundland. It gives me much glee to pull this little sucker out.
It's been replaced by the new GM Performance Parts wiring harness, with wiring that's built to run a big hefty V8 with eight hungry high-energy coils. The Miata relay was designed to handle a quarter of that.
As you can see, a number of other fuses and relays are also missing from the stock fuse box as they're simply not needed any more.
entry 1115 - tags: engine, 6.2, wiring