Eric S

Is it at all possible to use G4X to data log factory ECU's behaviour? Specifically I'd like to log below signals; SGT and SGC (MX-5 NA6/8 CAS) signals - TRIG1, TRIG2 Engine speed (rpm, deduced by G4X from CAS signal) Battery voltage (already logged by G4X) TPS (volts) - AV1 ECT (volts) - AV2 MAF (g/s) - AV3 IAT (volts) - AV4 Injector 1 duty cycle (ms) - DI1 Idle air control valve duty cycle (%) & frequency (Hz) - DI2 Ignition 1 trigger timing (ms) - DI3 Link CAN Lambda Makes me wonder if a buffer is needed between passthrough/breakout PCB and G4X in case the input impedance of G4X inputs affects the signal (ever so slightly) for factory ECU.

Been doing some back-to-back comparison between G4X and factory ECU on MX-5; mainly figuring out the idle air valve frequency and cold start behaviour. With G4X, the engine shutdown by turning the key from ON to ACC (or OFF) makes the engine shake and feels like the sparks want to fire (doesn't feel like a smooth shutdown compared to factory ECU, where I don't feel the engine shake at all when shutting down). It essentially cuts 12V to the ECU when key is turned away from ON and there's no dedicated digital input that tells the ECU 'I want to turn off the engine'. Is there something that can be done to allow more smooth shutdown?

Out of curiosity, does NA6 and NA8 CAS have the same trigger pattern? Mine is NA8 actually.

There was a minor fix on 6.20.17 for "VVTi MX5 trigger sometimes not syncing", but mine is not VVT so I figure it would not apply in my case. Almost flatten the battery trying to get it to throw trig errors but I got it, see attached. TriggerScopeLog 2 trig error.llgx

After upgrading to latest version v6.20.33, my MX5 randomly fails to start with trig error counter going up. I so far only encountered this issue when warm starting, cold starts have been fine. Attached both my tune and log. Note that I upgraded from 6.19.37 from memory.

Aha, forgot to dig into the help manual, thank you Vaughan. To my understanding the AUX9 and 10 are meant for electronic throttle (with its separate 12V supply), but I assume it has no effect on operation if used as general purpose low-side output? Also specs of "Auxiliary Output Specifications" applies to AUX11-16 as well (with 2A limit)?

Is there a summary table of all outputs (AUX, INJ, IGN) current limits/characteristics similar to what Motec has in their user manual (as per below)? Primarily looking for current limits on INJ1-6, IGN1-8 and AUX1-16. Currently re-wiring my car, and want to reserve high current outputs for other functions if possible.

Current setting is: Thanks you fellas, I was starting to think there's something else that was causing this Will try giving it more retard and more torque reduction time.

Hello hello hello. I can't seem to get rid of violent car jerking when overrun fuel cut deactivates while coasting (in gear) to a stop -- this jerking motion is amplified when AC is running. If I apply small amount of brake when overrun fuel cut transitions from active (>1600rpm) to inactive (<1600rpm), the rpm drop is smooth but still can feel the car wanting to accelerate for that brief moment as fuel cut deactivates and injects fuel. As soon as rpm drops below as per the deactivation table (1600rpm), it injects fuel but that brings up the rpm above 1600rpm which cuts fuel, then drops rpm below 1600rpm only to squirt to bring the rpm backup above the deactivation rpm; the cycle repeats 3-5 times before finally settling to idle. Tried playing around with the overrun fuel cut settings, but having no luck. Attached the setting file and can provide the log file through Dropbox due to file size.

Thank you, got it to work by configuring gear detection to analog and set source to AV12 (which doesn't have pin out on MX5 G4X anyway and won't go beyond ~0.02V), and set Gear 1 = 0.5V with +/- 1V tolerance. Nice work around. Tried the math block to average out the erratic speed reading, averaging made it better, but still it would occasionally display 300 km/h or something when travelling at 40km/h. Will be replacing the speedo cable soon.

According to the PCLink's help file, the conditions for 'In Driving Gear' status to show 'Yes' are: Gear position is Reverse (R), Drive (D), High (H), Low (L), 1, 2, 3, 4, 5, 6, 7 or 8 and the Clutch Switch is not active and the Neutral/Park Switch is not active. My car has two switches (transmission neutral switch and clutch pedal switch) wired in series, so when: In gear & clutch pressed = 0 Neutral & clutch pressed = 0 Neutral & clutch de-pressed = 0 In gear & clutch de-pressed = 1 Currently configured two digital inputs: DI3 = Neutral/Park (wired in, and status changes accordingly as per above) DI7 = Clutch (actual wiring doesn't exist, configured this way to make Clutch input to show as 'Inactive'). Since 'In Driving Gear' status is not changing even when both 'Clutch' and 'Neutral/Park' status say inactive, in what ways can I use 'In Driving Gear' status? It looks like I still need gear detection (R, D, 1, 2 etc). I'm trying to use 'In Driving Gear' as speed lockout on 'Idle Speed Control Setup' to reduce the idle dip when clutch is pressed from a moderate rpm (say >3000rpm). The wheel speed sensor is very erratic due to worn speedo cable.

Ah got it, good to know! I'll wire in to one of AV pin. Cheers.

Ah I thought of wiring it into one of spare AV input, but it made me think because whenever blower fan in off position, 10-12V is applied to the input. Since I don't know the input range/limits of AV input, and the maximum allowable error low/high value that can be entered on PCLink is 5V, I assumed the limit is 5V. Can the voltage applied to AV input be read above 10V continuously? If so I'll go with this method otherwise Adamw's series-ed diode method might be the easiest solution.

Can the input threshold of a digital input can be increased slightly? If it's fixed threshold, at what voltage will the input go 0 to 1? and the hysteresis if there is any? My MX5's AC blower fan knob is essentially a voltage divider and ECU only recognises fan speed 1 as HIGH and rest of speeds 2, 3 and 4 as LOW. So the AC clutch will only work when fan speed knob is turned to 1. Did some scoping, attached for future visitors. Since I'm making a custom adapter board for the "main" PCB, I can include some additional comparators with increased threshold (say 4V). I wanted to check if PCLink allows changing the input threshold; I vaguely recall Motec having the ability to adjust it but it's been long time. Cheers

No worries. I'm still yet to have any starting/sync loss issues with beta firmware When the official version gets released, I'll update it and carry on. Thanks for your help!

@Adamw Had zero issues so far with beta firmware (apart from one trigger error count log posted above), whatever your engineers did appears to have fixed it May I ask what the changes were internally?

Awesome! PM received. Will give the beta version a crack tonight and report back. Fingers crossed Update: So far beta firmware looks promising and the cranking sounds better than the older 6.16 firmware (sounds more smooth?). I encoutered only one trigger error count. Log attached for reference. I'll drive around next few days and see if I experience any start up issue. Cheers PC Datalog - 2020-10-7 11;25;42 pm Beta FW start OK, one trig error.llgx

Just want to bump if your firmware engineer had a chance at looking into the matter?

No problem, will wait for an update from your side.

Good to hear that, most forum searches (miata.net etc) I came across said that I need to remove the one of two rotor "blade" in order to generate only one pulse. But as you said, I'd like to see what the issue with trigger. So, good news is that 6.16 appears to be solid, 1-2 seconds of cranking and car starts right up. But bad news is after updating the firmware to latest version 6.18.11, starting the car became a hit-and-miss again. It's very strange since the trigger scope looks identical between "not starting" and "starting". For time being I'll use the 6.16 firmware. What do you suggest next?

Yep will give you an update later today. Also my car doesn't have trigger wheel at the crank, only CAS on the exhaust camshaft and it made me wonder if 36-2 trigger wheel can be used in conjunction with existing CAS? For instance, setting up trigger 1 on PCLink to use "multi tooth / missing" and trigger 2 set to "Cam Pulse Window" to sync? Not sure if the waveform of two uneven pulses (see attached), can be used to sync.

I see, thanks for sharing. So I started the engine few times in both cold and hot conditions, and it starts up well just like a factory ECU with 6.16.27. Started 7 times in total; 4 when cold and 3 when hot. Attached few more trigger traces, including the sync loss during cranking. Feel free to let me know if you'd like me to do some tests. Edit: I recall a jumper on PCB with silkscreen etched "MX5 1800", should that be jumpered? TriggerScopeLog.llgx 2020-09-21 1800 fw v6.18.8 not starting.llgx TriggerScopeLog.llgx 2020-09-24 1616 fw v6.16.27 run 2 cold start and idle.llgx TriggerScopeLog.llgx 2020-09-24 1616 fw v6.16.27 run 2 cold start OK.llgx TriggerScopeLog.llgx 2020-09-24 1617 fw v6.16.27 run 3 start OK.llgx TriggerScopeLog.llgx 2020-09-24 1654 fw v6.16.27 run 4 hot start OK.llgx

I only had a chance to start the car once this morning before driving to work with 6.16.27 firmware. The car started OK with no issues, I'll give it more start-ups after work today and see if the trigger sync looses randomly again. Attached trigger scope traces with 6.16.27 for your reference. Would you mind sharing what the changes with MX5 trigger were between 6.16 and later version of firmware? Coming from electronics/electrical background makes me very curious. TriggerScopeLog.llgx 2020-09-24 fw v6.16.27 run 1 cold start OK.llgx

Thank you, shall wait for your feedback

Map file attached!