NotJustToast Posted January 11, 2020 Report Share Posted January 11, 2020 So, I just tried to modify my AE86 original tach but removing the 30ohm resistor and using a 10ohm instead as Mark Panic instructed from Panic Wire. The tach works now but is not accurate and does some weird stuff compared to others that have done this same mod. I asked Mark and he said "If the tach is off outside of a certain point it's best to use a gp pwm table instead of "tacho".. You can start with a fixed duty of 60 and build the table by rpm. You should be able to do this without the car running." I have no idea what a gp pwn table is or how to do this. Any suggestions would be most appreciated. Car is using a Link Monsoon G4+ in a 1985 Toyota Corolla. Quote Link to comment Share on other sites More sharing options...
cj Posted January 11, 2020 Report Share Posted January 11, 2020 first, what sort of inaccuracy are you seeing? there is a way to calibrate before you try before jumping into alternate PWM tables. This assume tacho movement is linear, but just not correct. * multiplier - if the tacho needle only moves 800rpm for every 1000rpm of engine speed, set the multiplier to 1.2 (or 0.8 to correct it the other way) If you have something non-linear in the tacho (correct up to 4k then only moves 500rpm for every 1000rpm or something), then heres how to do generic PWM output instead of a tacho signal. Set an aux output to GP PWM (aux 1-4 will do up to 500hz, 5-8 only 300hz). Note that 500hz only drives a 4 cyl tacho to about 8k. This is a limitation of the GP PWM tables - a normal tacho output can do higher frequency. Set the condition to "only cond 1" and something generic like "rpm > 400rpm" Set PWM frequency to "table" Set the PWM DC table for this aux to all 50% (axis options dont really matter, ive set it to 2x cells of RPM but not required). This value may need to be tweaked for your car Set the PWM frequency table to have only 1x axis of RPM Set the numbers in the PWM frequency table to be the frequency of pulse sent to the tacho at that rpm. [freq = rpm / 60 * number of cylinders .... plus your fixup number] Quote Link to comment Share on other sites More sharing options...
NotJustToast Posted January 13, 2020 Author Report Share Posted January 13, 2020 Thanks for explaining the pwn tables, you really helped me understand how this works. I messed with the tacho duty cycle and multiplier and it seems the tach is pretty close to where it suppose to be "only checked up to 3k because I couldn't drive it today." Now the weird stuff.....When the tach is first plugged in everything sits at 0 where it is suppose to but the moment I switch the ignition on the needle never goes below 100-200 rpm, and when I turn ignition on "after the sweep" it sits at about 500 rpm. Once the car is running the needle does not move smoothly and has a jitter or hesitation movement when going up or down in rpm. If I quickly blip the throttle to around 2k rpm "on the laptop" my tach only makes it to 1300-1500 rpm. I uplaoded a few pics and a vid of the 2k blip for reference. Thanks again cluster rev 2k.mp4 Quote Link to comment Share on other sites More sharing options...
cj Posted January 15, 2020 Report Share Posted January 15, 2020 what are you currently using as your duty cycle? maybe try adding or removing 10-20% from it and see if that helps. You could also try putting in a 5ohm resistor rather than 10ohm as I seem to recall there was a lot of discussion on the correct value to use with some people even jumpering it with no resistor (but I wouldnt reccomend that). Its been a while since I modded a toyota tach and it was a couple years newer than yours but they certainly *can* function well from a link with just that resistor mod. Quote Link to comment Share on other sites More sharing options...
NotJustToast Posted January 16, 2020 Author Report Share Posted January 16, 2020 On 1/15/2020 at 1:41 AM, cj said: what are you currently using as your duty cycle? maybe try adding or removing 10-20% from it and see if that helps. You could also try putting in a 5ohm resistor rather than 10ohm as I seem to recall there was a lot of discussion on the correct value to use with some people even jumpering it with no resistor (but I wouldnt reccomend that). Its been a while since I modded a toyota tach and it was a couple years newer than yours but they certainly *can* function well from a link with just that resistor mod. I messed with the duty cycle a bit going as low as 20 and as high as 90 percent but it did not change anything. I went on amazon and ordered some 5ohm and 1ohm 1/4 watt resistors to try and will let you guys know what happens when I get them. Thanks for the help. Quote Link to comment Share on other sites More sharing options...
Brad Burnett Posted January 16, 2020 Report Share Posted January 16, 2020 When i modified my stock tach in my ae86, i didnt even use a resistor. Quote Link to comment Share on other sites More sharing options...
NotJustToast Posted January 16, 2020 Author Report Share Posted January 16, 2020 10 minutes ago, Brad Burnett said: When i modified my stock tach in my ae86, i didnt even use a resistor. So did you just remove the original resistor and bridge those 2 points with a wire and it worked fine? Quote Link to comment Share on other sites More sharing options...
Brad Burnett Posted January 16, 2020 Report Share Posted January 16, 2020 That is what i did. just removed the resistor and replaced with a piece of wire. Quote Link to comment Share on other sites More sharing options...
Herry Posted August 23, 2021 Report Share Posted August 23, 2021 Hello Brand Burnett... Can i ask you some questions...you not using the resistor and just replaced with a wire on your tach it worked fine like a normal?... I just have a same problem at here on my AE92 16valve tach it's not working at all with link stormX Aux output for tach.. Quote Link to comment Share on other sites More sharing options...
essb00 Posted August 24, 2021 Report Share Posted August 24, 2021 17 hours ago, Herry said: Hello Brand Burnett... Can i ask you some questions...you not using the resistor and just replaced with a wire on your tach it worked fine like a normal?... I just have a same problem at here on my AE92 16valve tach it's not working at all with link stormX Aux output for tach.. You have to change one resistor in the tachometer PCB (the resistor for tach signal input). You can follow @Sushpants guide here on this video.https://www.youtube.com/watch?v=y2TRMWldaQA&t=241s Quote Link to comment Share on other sites More sharing options...
Herry Posted August 24, 2021 Report Share Posted August 24, 2021 (edited) Thanks a lot essb00... I already watch the video & i try the same things before but the tach not working at all...now i just remove the resistor & replaced with wire now the tach really work well...thanks to Brad Burnett for the info... Edited August 24, 2021 by Herry Mistakes Quote Link to comment Share on other sites More sharing options...
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