trd101se Posted January 18, 2021 Report Share Posted January 18, 2021 Hi, just installed a G4X plugin into MX5, NA8C, 1.8L managed to get the engine start up on based map, but have problem with the original tachometer not working. also, the CEL also does not turn on, despite setting is turned 'on'. Quote Link to comment Share on other sites More sharing options...
koracing Posted January 18, 2021 Report Share Posted January 18, 2021 So your MX5 is a 1994 or 1995? I assume you have the little jumper on the board set to the 1800 position. The base maps don't appear to have the tach output set up. You may need to move a pin to one of the aux outputs to get the tach working. I had a customer car with a vvt swapped 1993 that we use the condenser fan ouput aux2 (OEM pin 2S I believe) to drive the tach just fine as it was a track car and did not have AC - only requirin a single fan output. Alternatively Aux3 output (Pin 37 or OEM pin 1i could be used to drive the tach also) as it isn't used in the 94-95 for anything that I can tell. On the Check engine light, that should all be the same aux4 output, so I'm unsure what the issue may be on your vehicle. If you can ground the check engine light pin on the harness and determine if the light turns on (with key on), figure out what position that is and if it matches up to the wiring diagram pinout in the help menu. Quote Link to comment Share on other sites More sharing options...
Vaughan Posted January 18, 2021 Report Share Posted January 18, 2021 have you set the jumper to bridge the two pins by the header? Quote Link to comment Share on other sites More sharing options...
trd101se Posted January 19, 2021 Author Report Share Posted January 19, 2021 19 hours ago, Vaughan said: have you set the jumper to bridge the two pins by the header? yes, i've bridged the two pins labelled 1800 MX5 right behind the ECU connectors. but tacho still doesnt work. Quote Link to comment Share on other sites More sharing options...
trd101se Posted January 19, 2021 Author Report Share Posted January 19, 2021 22 hours ago, koracing said: So your MX5 is a 1994 or 1995? I assume you have the little jumper on the board set to the 1800 position. The base maps don't appear to have the tach output set up. You may need to move a pin to one of the aux outputs to get the tach working. I had a customer car with a vvt swapped 1993 that we use the condenser fan ouput aux2 (OEM pin 2S I believe) to drive the tach just fine as it was a track car and did not have AC - only requirin a single fan output. Alternatively Aux3 output (Pin 37 or OEM pin 1i could be used to drive the tach also) as it isn't used in the 94-95 for anything that I can tell. On the Check engine light, that should all be the same aux4 output, so I'm unsure what the issue may be on your vehicle. If you can ground the check engine light pin on the harness and determine if the light turns on (with key on), figure out what position that is and if it matches up to the wiring diagram pinout in the help menu. its a 1995. yes, jumper connected both pin but cant get it work. The car runs 2 cooling fans, so aux2 is occupied. Aux3 is the one to go... can I ask where to trace for the tacho wire? do I trace all the way to the dash connectors? By standard, there should be a wire connecting ecu to dash for tacho, am I right? I tried trigger the CEL(aux4) with disconnecting a sensor, and the ecu shows the CEL, but nothing on the dash. alright, will give a try Quote Link to comment Share on other sites More sharing options...
koracing Posted January 19, 2021 Report Share Posted January 19, 2021 I'm no Miata expert, but I've tuned many and messed with a few. I think the tach is driven from the ECU on all of the NA6/NA8 models. According to the pinout information I have the Tach signal in 95 is on pin 1F or link pin 50. 37 (Aux3) isn't too far from 50. Quote Link to comment Share on other sites More sharing options...
koracing Posted January 19, 2021 Report Share Posted January 19, 2021 Also, FYI, the knock input isn't wired on your ecu, but it can be added if you decide to install a NB knock sensor. Quote Link to comment Share on other sites More sharing options...
Vaughan Posted January 19, 2021 Report Share Posted January 19, 2021 On the 1.6 motors the signal comes straight from the igniter, on the 1.8 NA motors it looks like it comes from the coils and that bridged pin just adds a pullup. Also regarding CE lights they don't all have them, my mx5 is admittedly a very basic one (1989 NZ new) but it is short quite a few things, this can be checked by pulling the dash cluster but that does involve removing the very fragile cowl. https://www.miataforumz.com/1990-200-Miata-Wiring/95sys.pdf Quote Link to comment Share on other sites More sharing options...
koracing Posted January 19, 2021 Report Share Posted January 19, 2021 According to this: the Tach output is on 2I for 94-95 - which link has listed in the pinout as the Tacho pullup. I know on 90-97 Miatas I've tuned with VVT swapped engines I was able to use Aux1-4 to drive the tach, however, so if all else fails that might be worth a go. I don't know where I got 1F from, but the diagram Vaughn linked shows nothing on that pin. In this same diagram it shows the tach being driven directly from the coils when you scroll down to the cluster. The check engine light according to the diagram above as well as the the pdf diagrams list the CEL on pin 1E. Quote Link to comment Share on other sites More sharing options...
trd101se Posted January 20, 2021 Author Report Share Posted January 20, 2021 23 hours ago, koracing said: I'm no Miata expert, but I've tuned many and messed with a few. I think the tach is driven from the ECU on all of the NA6/NA8 models. According to the pinout information I have the Tach signal in 95 is on pin 1F or link pin 50. 37 (Aux3) isn't too far from 50. update on today progress, koracing, following your pointers, traced and found there is no wire in #37 in my miata, so I tested #50 assigned Aux3 in tacho setting, then switch the wire to #37 slot and managed to get it work, with a setting on HIGH side. Vaughan diagram is applicable to this 95' 1.8L Miata, no B/W wire on #37. Thank you very much, koracing and Vaughn for sharing the useful diagrams and valuable pointers. I'll work on the CEL next and noted on the knock sensor pull up. Vaughan 1 Quote Link to comment Share on other sites More sharing options...
trd101se Posted January 23, 2021 Author Report Share Posted January 23, 2021 managed to get the CEL pull up and working. thank you once again guys and have an wonderful weekend. Quote Link to comment Share on other sites More sharing options...
koracing Posted January 23, 2021 Report Share Posted January 23, 2021 What did you end up doing to get the CEL working? Quote Link to comment Share on other sites More sharing options...
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