Tune 'n' 'charge 'n' tune
Posted: Mon Feb 20, 2017 9:35 pm
So around 2 years ago, Loren parted out a Miata he had picked up. It was supercharged (JacksonRacing - probably an M45), had a wideband and some other gauges, timing controller, fuel card, a couple other gizmos. I bought all that junk, with the intention of putting it in my car. It wasn't a 100% kinda thing, for me anyway, as the stuff was on an NB (second gen) Miata, and mine is an NA. Both 1.8s, but, well, you know. Biggest question was whether the "dummy" throttle body would fit. Anyway, being how I roll, the parts sat while I did other stuffs. Some of that stuffs included searching the interwebz to try to find out if an NB supercharger kit would fit on an NA. No clear answer, but the signs collectively pointed to yes.
Soon, opportunity knocked, and a plan was concocted to git'r'done while codriving the Fastiva while Ben was away on walkabout. Well, that came and went...although I did eventually test-fit the dummy throttle body, and it is a match, so, full-speed-ahead. Well, half-speed anyway. I think Ben got back over the summer at some point. I've lost track. But the Fastiva is fun...
Well, after a few discussions and some eavesdropping and more reading, I figured the way to go was to ditch all the electronic gadgets and just go Megasquirt. Even just saying that is intimidating. So the plan became to revert the electronics and stuff in my car (modded ecu, timing controller, timing advance) back to stock, put in the wideband, get the Megasquirt, tune it without the supercharger, then put on the 'charger and then retune it from there.
I got the wideband, boost gauge, and voltmeter in this weekend, put back the stock ECU, removed the Bipes timing controller, and reset base timing, to stock 10 btdc (for now).
Yeah, big deal - gauges in a Miata. But I'm pleased. Electrics is my weak point, I'm a crappy solderer, but I managed, all the joints are heatshrinkwrapped, and it all worked at the first turn of the key (and kept working). And, good vacuum and the charging system is healthy. No surprises on AFRs with the stock ecu.
So, here's what for me is a challenge: My '94 Miata is OBD1, but it has a 4 wire o2 sensor. I've got the narrowband output of the wideband o2 sensor spliced into the stock signal wire to the ecu (so the computer gets it's narrowband afr info and the car runs nicely). The other 3 wires I left connected to the old narrowband, which is wiretied under the hood. I understand that the old o2 sensor has a heater (even though it's OBD1), and if I cut those heater wires, at best I'll get a CEL (which I don't want to deal with). The internet says I can get two 50w-100ohm resistors in parallel between the heater wires to trick the ECU, and cut out the old o2 sensor. BUT, it doesn't heat up. Even after a decent drive, whereas it shoulda been several hundred degrees...nothing. Would a dead o2 sensor not heat up? I guess I need to shave a little insulation off the heater wires and see if there's current in them? Once I get the Megasquirt, it's not an issue at all, but I'm learning, and this has me curious. (edit: just read a bit more, and just 'cuz it's OBD1 it still - obviously - can have a heated o2 sensor).
Anyway, gotta order the Megasquirt, learn how to datalog, and keep up my momentum before another 2 years goes by...
Soon, opportunity knocked, and a plan was concocted to git'r'done while codriving the Fastiva while Ben was away on walkabout. Well, that came and went...although I did eventually test-fit the dummy throttle body, and it is a match, so, full-speed-ahead. Well, half-speed anyway. I think Ben got back over the summer at some point. I've lost track. But the Fastiva is fun...
Well, after a few discussions and some eavesdropping and more reading, I figured the way to go was to ditch all the electronic gadgets and just go Megasquirt. Even just saying that is intimidating. So the plan became to revert the electronics and stuff in my car (modded ecu, timing controller, timing advance) back to stock, put in the wideband, get the Megasquirt, tune it without the supercharger, then put on the 'charger and then retune it from there.
I got the wideband, boost gauge, and voltmeter in this weekend, put back the stock ECU, removed the Bipes timing controller, and reset base timing, to stock 10 btdc (for now).
Yeah, big deal - gauges in a Miata. But I'm pleased. Electrics is my weak point, I'm a crappy solderer, but I managed, all the joints are heatshrinkwrapped, and it all worked at the first turn of the key (and kept working). And, good vacuum and the charging system is healthy. No surprises on AFRs with the stock ecu.
So, here's what for me is a challenge: My '94 Miata is OBD1, but it has a 4 wire o2 sensor. I've got the narrowband output of the wideband o2 sensor spliced into the stock signal wire to the ecu (so the computer gets it's narrowband afr info and the car runs nicely). The other 3 wires I left connected to the old narrowband, which is wiretied under the hood. I understand that the old o2 sensor has a heater (even though it's OBD1), and if I cut those heater wires, at best I'll get a CEL (which I don't want to deal with). The internet says I can get two 50w-100ohm resistors in parallel between the heater wires to trick the ECU, and cut out the old o2 sensor. BUT, it doesn't heat up. Even after a decent drive, whereas it shoulda been several hundred degrees...nothing. Would a dead o2 sensor not heat up? I guess I need to shave a little insulation off the heater wires and see if there's current in them? Once I get the Megasquirt, it's not an issue at all, but I'm learning, and this has me curious. (edit: just read a bit more, and just 'cuz it's OBD1 it still - obviously - can have a heated o2 sensor).
Anyway, gotta order the Megasquirt, learn how to datalog, and keep up my momentum before another 2 years goes by...