Those of you who used a NA (Mk1) donor, will have found that the speedo cable makes a very sharp bend at the transmission. Every single car that I know of ended up with a broken cable because of this. The only solution is to make a hole in the body to feed the cable through or use the NB (Mk2) cluster with its electrical drive gear (it’s a direct swap against the mechanical drive gear).
However, there is a much easier solution. The mazda gearbox has a metric M22-1.5 thread as do old 80′s and 90′s Toyota’s. Most (all?) RWD Toyota’s used a 90° angled drive to prevent this problem. The part is a straight fit for the Mazda transmission!
The original Toyota P/N is 83770-30070 and it is meanwhile superceeded by P/N 83770-22100.
Installed the S2000 cluster today. I used a powdercoated piece of aluminium sheet that I cut out and painted satin black. This went fairly well and looks a lot better than the MX5 cluster.
I’m not too fond of that amber color so I’m going to change it to something else. I haven’t yet decided which color to use, probably blue or multicolor.
Remember those yellow headlights we used to see years ago? They were introduced in France in 1936 and were required until 1993. They now are no longer required but they’re still approved in Belgium. I’ve always liked them, so when I came across a set of NOS (New Old Stock) on Ebay, I just had to have them! A bit expensive, but very rare nowadays.
My cluster has 143K kms and my car only has 12K so I need to adjust the odo. I have a programmer to modify the code in the cluster, but I’m hesitant to try it. I wouldn’t be the first one to brick the cluster. The easy solution is to just turn it forward to 12K. The maximum frequency that the cluster can handle is 24kHz, which corresponds to about 900km/h. At that speed, it takes over 44 days to turn it over to 12K.
Mmm… Anyway, here’s a schematic that works fine.
If you use a 12V source, use a voltage divider at the output to reduce the voltage to 5V because the speedo wants a 3-5V input.
It arrived today and was very easy to install. Only 4 wires (gnd, +12V, speed in and speed out). It took about 30 mins to install and finally the speedo indicates the correct speed. I should have gone for a Speedohealer from the start. So, if you plan on doing the same thing, don’t start messing and buy this immediately. It’ll same you a lot of time and swearing .
Next is the installation of the cluster in the car.
Well, ain’t that a bummer. After going for my first testdrive, it turns out that my speedo is reading about 20% slow compared to my gps. I could only do a short drive, but it immediately was very clear that the speedo is off.
This means that the transmission is sending out 4000 ppm, not 4800 like I assumed. I’ll have to use a 39 multiplier, something Jean’s board can’t do, so I’ll have to look for an other solution.
I could program a pic to do the conversion, but this project has already taken too much of my time. I’ve been messing about with VR circuits, voltage dividers and PWM converter circuits for too long. I don’t want to spend several days designing a pic based circuit, building and testing it, buying a programmer to progam the pic etc. So, I decided to take the easy and fast route and ordered a SpeedoHealer V4 today. 78€ well spent .
I was sending a 9V signal into my PWM converter that can only handle 5.3V … luckely I had 2 chips
Turns out I was feeding my circuit with a too high signal. The circuit can only handle 5V and I was sending 9V in it (oscilloscope was set to ~AC in this pic).
Speed conversion. Red is 5.6V input, blue is 5V output (freq x32). The chip can only handle 5.3V, so I need to lower the input a bit.
23.8Hz = 28km/u as indicated by TunerStudio
Perfect! 5V square wave in (red trace) and 5V square wave out with x32 frequency
After modifying the signal to 5.6V, it was working perfectly, but I didn’t want to take the risk of blowing up the chip, so I reduced it to 5V exactly.
I got the speedo working with a PWM signal generated by a generic output from the Megasquirt. I then send this signal through a PWM converter with a 32 multiplier. This generates a 499Hz signal that indicates a speed of 18km/u, what corresponds with what I calculated. It was kinda cool to see the odo ticking forward. I let the car run for 8.8km . The speedo should be spot on .
Unfortunately, I didn’t get it working in the car yet. My transmission generates an AC signal that I convert to a square wave and send to the PWM converter. Although it works with my self generated signal, it doesn’t work with the signal coming out of my VR converter. It looks ok on the oscilloscope though. I’m a bit puzzled, but I’m sure I’ll figure it out eventually.
Decided to take another look at the speedo today. Turns out I forgot to solder the wire for the VSS signal. After soldering in that last wire, the speedo works. It indicates 3 km/h, not much, but at least I now know the speedo is working.
Did an update of a WordPress plugin yesterday and I didn’t think it was necessary to take a backup of the database. I was wrong. The update deleted all columns in the database, so all links to the pictures are gone. I spent about 5 hours yesterday and today putting back the correct links. I had to look up all my pages and posts in google cache, figure out which pictures I had used, find them back in about 55 albums and correct the links. Not fun. I think I have another 2 or 3 hours work left to get everything back in order.
Just after ordering I found this circuit. Needs only a couple of resistors and 2 transistors, so this is a good option as well. Probably gonna stick with the LM1815 based circuit though, now that I’ve ordered the chip …
Put the Westfield with its wheels in the air to test the speedo. Nothing .
Don’t know exactly why it isn’t working, my oscilloscope gets a reading so it should indicate something.
At 50 km/h (13.889 m/s) I have 41.5 Hz, iow 41.5 pulses for 13.889 m or 4800 pulses per mile. This is weird as it’s supposed to be 4000 ppm. Either way, it should read something, even at 4800 ppm.
The speedo expects 156000 ppm. I drove the car up to 170 km/h, so the speedo should at least indicate 5 km/h, but I get nothing.
Difficult to diagnose if it’s the speedo or a problem with my signal. Will have to do some more testing.
Since the signal is 4800ppm, I can use Jean Bélanger’s PWM converter circuit to multiply the square wave signal by 32 (actually 32.5, but 32 is close enough). However, if it turns out to be 4000ppm, my speedo will be reading 20% slow with the 32 multiplier …
I have a 90-94 ‘real’ oil pressure sender but no real oil pressure gauge in my S2000 cluster, so I’m using the MS3X to trigger my oil warning light at a preset value.
The wire coming from the sensor no longer goes to the instrument cluster but to the MS3X on port ADC13 instead. Since the oil pressure sender outputs no voltage (it’s a simple lineair resistor), a bias resistor is added on the MS3X card in the R67 position. The oil pressure sender has a fairly low resistance so I used 330ohm to get good accuracy. Worst case, this pulls about 15mA through the sensor so it shouldn’t be a problem.
The factory manual mentions these resistor values:
0psi => 52 ohms
90psi => 16 ohms
With a 330 ohm bias resistor we can calculate the corresponding input voltage on ADC13:
0psi => 5*52/(52+330) = 0.68V
90psi => 5*16/(16+330) = 0.23V
With this we can calculate the 0V and 5V values in Tunerstudio:
0V => (90-0)/(0.23-0.68)*(0-0.68) = 136
5V => (90-0)/(0.23-0.68)*(5-0.68) = -864
Enter these values in Generic Sensor Input 1
sensor – source: Spare ADC (ADC13)
Transformation: Linear mode
Now you can use a spare output port to trigger the oil warning light when oil pressure goes below 15psi. I use these values:
Output port IAC2
Power on value: 1
Trigger value: 0
Output channel: sensor01 < 15 Hysteresis 2
If you have a real oil pressure gauge, you probably want keep using it (no point in disconnecting a perfectly good oil pressure gauge!). You’d obviously need no bias resistor and you need to make sure you do NOT send over 5V into the ADC port. The gauge works with 12V, so it’s probable that you measure more then 5V over the oil pressure sender (I never checked though). If so, you’ll have to use a voltage divider to bring it down to 5V.
Obviously, you’ll have to do some math since you’re now using an unknown bias resistor (easy to calculate its value).
Honda connectors removed and wires soldered in. I always use the oem Mazda color codes (an old wiring loom is super handy for this kind of thing) as it's easier to spot mistakes.
The Honda connectors are removed and new wires soldered in. I always use the oem Mazda color codes (an old wiring loom is super handy for this kind of thing) as it’s easier to spot mistakes. I also made sure to have a stress relief for the wires should I ever accidently rip out the connectors. It’s not pretty, but it does the job just fine.
As always, more pictures in the S2000 album.
The NB miata gearbox has a VR sensor which outputs an 4000 ppm AC waveform. The miata instrument cluster has a built in VR conditioner to convert that signal to a square wave signal which drives the miata speedo. This square wave is also used as an input for the megasquirt.
MX5 circuit board installed with some stick on spacers to prevent it touching the S2000 pcb.
The problem is that when I remove the miata cluster, I’ll no longer have the VR conditioner. Since the megasquirt cannot directly accept the AC waveform, I’d have to build a new VR conditioner in the proto area. I found it easier (and faster) to remove the small pcb/display (with VR conditioner) from the miata cluster and install it inside the S2000 cluster. Just like before, the output of the miata pcb goes to the megasquirt and the megasquirt output will be used to drive the S2000 speedo.
I installed the Modifry ECT module inside the Megasquirt. This module takes the signal from the coolant temp sensor and converts it to a format that the S2000 cluster understands. The input of the module taps into the sensor wire, the output goes to the S2000 cluster. The module is fully programmable and even has an adjustable alarm output (as a warning for overheating for example).
For my own reference:
ECU pin 1G is Modifry CLT out to S2000 cluster 2A (V/W) via an additional wire
ECU pin 2D is MS3 VSS input from MX5 module 2L (W/B)
ECU pin 2A is MS3 VSS output to S2000 cluster 2O (P/L) via an additional wire
this is what the S2000 cluster will look like in the westfield (miata) housing.
The S2000 cluster is a lot smaller than the miata cluster (that was the reason of doing the swap all along), so I’ll have to make a template out of plexi to make it fit. Shouldn’t be too hard to do though. A bit of plexi and some paint or vinyl sticky stuff should do it. I haven’t yet decided which color, probably matte black.
I don’t have the S2000 connectors and I don’t want to cut the wiring of the car, so I decided to remove the S2000 connectors from the pcb and replace them with the connectors from the miata cluster. Removing the S2000 connectors proved to be a bit challenging and in the process I managed to let my dremel slip and touch the pcb in one or 2 places. It took me quite a while to repair the damage. As Murphy would want it, I cut right in the middle of a bunch of very thin traces. Luckely i managed to avoid cutting into components.
The problem with the miata connectors is that they are part of the instrument cluster, so I had to cut them out. It looks worse then it is really.
Miata connectors glued in and circuit ready to be soldered.It looks messy, but everything is pretty firmly glued in.
I cut some holes in the S2000 cluster and glued the miata connectors in. The left one was a straight fit, the right one needed enlarging and the middle one is an all new hole. I’ll probably add a couple of screws to make sure they don’t come loose.
I used the corresponding bits of the circuit board layer and will solder the wires straight on them.
Luckely, I can still see the most important part of the tacho, but I'd like to see more of the odo.
As I can’t really see all my dials, I decided to buy a Honda S2000 instrument cluster today. It’s a lot smaller and should be entirely visible through the steering wheel.
The cluster is a bit of a pain to connect because the S2000 has a 156000 ppm (pulses per mile) speed sensor, while the miata has a 4000 ppm. I’ll have to come up with a way to multiply the stock signal by 39.
Also, the coolant sensor does not just measure the resistance (voltage) of the coolant sensor. Instead, the ecu measures it and sends a 5V signal that has a 30ms high pulse and a 150ms to 1500ms low pulse, relavite to the temperature, so that’ll require some modifications as well.
Oh, and I’ll have to reprogram the km reading, because I only have 12K kms, not 142K!
I have no idea yet if it’ll fit inside the Westfield dash as the upper part of the cluster is rather high. I’ll make it fit if necessary.
the color filter can be easily replaced with a different color
I’m also planning on changing the color of the display because I don’t like the yellow/orange backlight. It’s just a piece of plastic, so it shouldn’t be too hard to swap it with a different color. The bulbs are a bit yellow-ish as well, so I’m going to look into replacing them with bright white leds.
Built the megasquirt this weekend. The MS3 build is a lot easier than my previous MS2 builds. With the MS3X, most of the extra circuits and flyback diodes can be omitted, greatly facilitating the build. Again, I made the MS3 fully plug and play. I really don’t like using extra wiring looms. The 64pin connector has more than enough room to be put inside the case, so why make a wiring loom!
Build instructions here.
It took very long this time. Nearly 3 weeks, but the Megasquirt finally arrived .
Your item was delivered in BELGIUM at 10:22 am on October 12, 2011.
Arrival at Post Office, October 12, 2011, 7:30 am, BELGIUM
Customs clearance processing complete, October 11, 2011, 8:44 pm, BELGIUM
Decided it was time to move to a new website. The old site was made with Site@School but development of the software has stopped because of an arguement between the developers. The main developer decided to release a fork (SyndeoCMS), but he made a new album module and I didn’t like it. I lost a lot of pictures converting to SyndeoCMS and had to redo quite a bit to get the site going again.
Site@School is completely dead by now, so there was no point in going on with that CMS.
I’ve now choosen for WordPress 3. I had a lot of work transferring my build diary to the WordPress, but at least I now have a mature CMS. I’m also using a wonderful plugin (Shashin) that allows me to insert my Picasa albums in my website. All pictures you see on my website are hosted on Picasa, they don’t take up space on my host! The beauty about it is that all captions I made in Picasa, are visible on my website as well. With the old CMS, I had to write them in the database, with the result that they’re all gone once I switched to WordPress.
The one downside to using WordPress is that all my hyperlinks are now dead. My site had quite some visitors and especially my Megasquirt build how-to. I guess in time, folks will start finding the link again, Google will pick it up very fast.
Decided to order a new megasquirt today. Not that I need a new MS, but I just like building them . I’m replacing the MS2Extra with a MS3 + MS3X. Plan is to try and make a PnP version like my other MS. Don’t know if the case is large enough though. If it’s anything like my previous orders, it’ll take less than a week to get to Belgium and 2 weeks to get through customs .
DIYAutoTune.com
------------------------------------------------------
Order Number: 45180
Detailed Invoice: https://www.diyautotune.com/catalog/account_history_info.php?order_id=45180
Date Ordered: Monday 19 September, 2011
Products
——————————————————
1 x MegaSquirt-III w/PCB V3.0 – UnAssembled Kit (MS330-K) = $365.00
1 x MegaSquirt-III MS3X Expansion Card (MS3Xpander) = $90.00
——————————————————
Sub-Total: $455.00
United States Postal Service (1 x 2.63lbs) (Express Mail International (3 – 5 business days)): $44.25
Total: $499.25
I did some modifications to the intercooler. The car had a tendency to always run between 94-96°C while cruising. These are quite normal temperatures, but I didn’t like it because that’s the point where the fan turns on, so they were on quite a bit.
I had a shroud welded on the intercooler. Added a door rubber from the donor around the edges so that it presses right up against the inside of the nose. Not difficult to do, just time consuming to get the fit right. Must have put the nose back on 20 times or so .
The result is spectacular. I never go over 88°C while cruising and it sometimes even drops to 85°C. Almost too cold. In stop and go traffic, temps rise to 94°C, but as soon as the fan kicks in, they immediately drop back to 88°C. Perfect!
Did some modifications to my coolant reroute because I had a hose pop off a couple of times. My old setup is made up of a couple of hard pipes connected together with hoses. Unfortunately, the pipes don’t have beads on them, so they easily pop off.
I’ve replaced everthing with a single long hose, straight from the back of the engine to the radiator. I put a T-bolt clamp on each side, to make sure it won’t pop off again.
I installed Tunerstudio on my 3 pc’s (desktop, laptop and car pc ) and I put the project in Dropbox (it’s free). Whenever I have internet access, all computers synchronise, so my project is always synced on all computers, just like that. The car pc has GPRS so it syncs while driving . It also has wireless, so even without GPRS, it syncs when I arrive at home and drive the car into the driveway . The nice thing about dropbox is that all files are also available online, so you can access your project from any PC. It even keeps track of deleted files etc. Nice stuff.
If you don’t know what dropbox is, check it out. If you sign up through this referral link, you (and I) get 250MB extra space.
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