freedomgliのブログ一覧

Now that winter's icy cold grip has finally relented, I was able to get some more work done on the Miata this weekend.


Empty engine bay. Note all the tags to identify various hoses and plugs and what not. Rubber caps keep fluids in and foreign objects out.


Detailing engine bay


Old 1.6 engine and transmission are out.


PS delete and AC compressor brackets swapped over to new motor


1.6 oil pressure sender unit swapped over to new motor. 1.6 cars have true oil pressure senders, but all 1.8s - aside from 94s - have idiot lights turned into gauges. Hence, you’ll want to install your original oil pressure sender in place of the 1.8’s oil pressure sender. Your original sender is pretty big, whereas the sender on the new (post-94) engine is pretty small, but they both use the same spade connector and thread into the same place in the same manner.

I also deleted the NB knock sensor (blind hole right above the oil pressure sender) because whatever sticky black goo the microphone was potted in was leaking all over the place. Maybe one day I'll buy a new knock sensor and figure out how to configure the Megasquirt to use it. Basically, you have to tune the filters to detect knock (vs. normal combustion events) and then create a map to pull ignition timing when it detects knock.


Flyin' Miata ignition coil relocation bracket and M-tuned coolant reroute fitting installed. I used an OEM gasket instead of the M-tuned supplied sticky foam gaskets since I had plenty of access and could ensure the surface was immaculately clean of all old gasket material. I imagine doing this install while the motor is in the car would be quite a challenge and the sticky back gaskets would be useful in that case. Time will tell if I made the right gasket choice. Here's hoping for a lifetime free of coolant leaks!


Side view of the M-tuned coolant reroute fitting on back of head. I also installed new temp sensors. The small sensor is for the instrument panel temperature gauge and came with its own thread sealing paste applied from the factory. The large green sensor is for the ECU. I wrapped the threads in Teflon tape to seal them from leaks. The Megasquirt EMS will also use the green sensor to monitor coolant temps for radiator cooling fan control instead of the thermistor that 1.6 cars originally had on top of the front thermostat housing that's since been removed.


Longer screw for Flyin' Miata coil bracket wire harness clip. The screw supplied by Flyin' Miata was too short to engage the nylock feature of the supplied nut. I used a longer screw that would fully engage the nylock so it won't vibrate loose.


Original 1.6 ignition coil signal wire configuration.


New 1.8 ignition coil signal wire configuration. When doing this swap you must reuse your 1.6 coils, as the 1.8 coils aren’t compatible with the 1.6 electronics. The easiest method is to simply bolt your 1.6 coils into the Flyin' Miata ignition coil bracket, which will allow you to bolt them to the 1.8 valve cover. Most plug wires won’t fit with the coils in their original orientation, though - from left to right, the 1.6 plug wire order is 2-3-4-1 and the 1.8 order is 1-4-2-3 (1 being the front spark plug). By swapping the signal wire between the two coils, you’ll match your 1.6 coils to the 1.8 plug wire order and your plug wires will work (all 90 - 00 plug wires are the same). There are two wires (underneath a plastic cover) on the bottom of each coil. The power wire is red, and you can easily tell that the wire goes to both coils. The other wire is the signal wire. Swap those signal wires and use the correct (1.8) plug wire order.


1.6 plug wire order. Looks like #1 and #4 were actually switched at some point, but it doesn't really matter much since the ignition system is batch fire wasted spark. I actually prefer this routing as it looks cleaner and more organized and I don't like it when plug wires criss cross-each other as that increases radio frequency interference and the chances of arcing between leads.


1.8 plug wire order.


Servicing the new transmission on the workbench. The goal was to swap the Toda Racing flywheel and nearly new clutch from the old motor to the new one and give the new transmission some new seals front and rear.


Transmission front cover with new oil seal installed. Note correct seal orientation. When fitting the new paper gasket it helps to smear a thin film of oil on it so it sticks to the transmission gasket sealing surface while you reinstall the front cover. Don't forget the little oil shim (not pictured here). I also grease the front cover snout so the throwout bearing slides smoothly and the clutch fork pivot and the transmission input shaft splines. FYI the NA clutch fork boot is not the same size as the NB clutch fork boot.


FYI for comparison purposes. The 1.8 (NB1) engine mount bracket on left vs. 1.6 (NA6) on right.


Garage Star alternator pulley installed. The alternator/water pump belt must be tensioned properly and you'll need an impact driver to remove and install the nut that affixes the alternator pulley.


New 1.8 motor and trans ready to go back in.