Sushpants Posted July 26, 2020 Report Share Posted July 26, 2020 Hello, I have an Atom X g4x running my AE82 with a 4AGE 20v Blacktop swap. I've been trying to get the stock AE82 tachometer to work with my coil on plugs & ECU. First, I tried using a tach booster which worked great until the rpms were over 6.5k. I then removed the tach booster and swapped the tach cluster resistor to a 1k connected it directly to the Atom X. The tach works with the output from the Atom X but the reading is off by about 600rpms. When I power on the car, I noticed the tach needle will read about 600rpms when engine is off and only drop to 0rpms when switched off. Is there a way to adjust that initial signal or is there something else i should be doing to get the tach to read accurately? Thanks! Sushpants BTW, I'm making an Link ECU install video series for my Corolla FX16 GT-S: https://youtu.be/3GDTDJv3IC8 https://youtu.be/245fLDX0jaM Quote Link to comment Share on other sites More sharing options...
Adamw Posted July 26, 2020 Report Share Posted July 26, 2020 2 minutes ago, Sushpants said: When I power on the car, I noticed the tach needle will read about 600rpms when engine is off and only drop to 0rpms when switched off. The aux output wont even be outputing a pulse when the engine is not running, so it sounds like the problem may lie elsewhere. Quote Link to comment Share on other sites More sharing options...
Sushpants Posted July 26, 2020 Author Report Share Posted July 26, 2020 I'll try unplugging the tach wire and see if it goes up on its own. Quote Link to comment Share on other sites More sharing options...
essb00 Posted August 7, 2020 Report Share Posted August 7, 2020 It is very usual with Toyota tachs to have off readings after power on (engine still off) whenever the capacitors on the gauge PCB have bloated. If I remember it right, there should be two 6.8uF 25V capacitors. They're not so easy to find, but they can be substituted with 10uF 25V without any problems. Quote Link to comment Share on other sites More sharing options...
Sushpants Posted December 2, 2020 Author Report Share Posted December 2, 2020 I finally got to the bottom of the issue. The meter movement was the cause of the needle rising when power would be applied to the tach controller. I think in the process of me replacing the signal resistor I bumped meter movement out of calibration. I made a complete video on how to fix it and how to adjust the tachometer range: https://youtu.be/y2TRMWldaQA essb00 1 Quote Link to comment Share on other sites More sharing options...
Dougy Posted January 7, 2021 Report Share Posted January 7, 2021 Sushpants where did you wire the tacho to on the ECU? I've got the same setup, link g4x, cop. There's not auxiliary output for the tacho. Do you just tap into one of the signals for the COP? Thanks Quote Link to comment Share on other sites More sharing options...
Sushpants Posted January 7, 2021 Author Report Share Posted January 7, 2021 Hey Dougy, That's what I did at first but it didn't work well for me, the tach wouldn't read higher than 6k rpms. I ended up making a video on how to diagnose and fix the tach: LilMoosh 1 Quote Link to comment Share on other sites More sharing options...
Dougy Posted January 7, 2021 Report Share Posted January 7, 2021 I see in you're video that you used aux output 3 for the tach signal? What did you do with the fuel pump signal that was originally there? I've currently got aux 1 and 2 as ISC, aux 3 for the fuel pump and aux 4 for the VVT. I've got one of the COP wires spliced at the moment so I'm going to try change the resistor in the tacho but not 100% sure where to move the signal to if that fails. Thanks Quote Link to comment Share on other sites More sharing options...
ellisd1984 Posted January 10, 2021 Report Share Posted January 10, 2021 do the coils not have a feedback pin and could that not be used? Quote Link to comment Share on other sites More sharing options...
Sushpants Posted January 10, 2021 Author Report Share Posted January 10, 2021 Hey Dougy, I ended up moving my the fuel pump to a relay and using that aux output for the tach. You could gain 2 outputs by setting up a wasted spark setup. & ellisd1984 - The coils do have the feedback pin, but that's another aux input which the ECU is doesn't have many of. Quote Link to comment Share on other sites More sharing options...
ellisd1984 Posted January 10, 2021 Report Share Posted January 10, 2021 3 hours ago, Sushpants said: Hey Dougy, I ended up moving my the fuel pump to a relay and using that aux output for the tach. You could gain 2 outputs by setting up a wasted spark setup. & ellisd1984 - The coils do have the feedback pin, but that's another aux input which the ECU is doesn't have many of. no I mean could the feedback pins be tied together and fed directly to the tach? Quote Link to comment Share on other sites More sharing options...
Sushpants Posted January 11, 2021 Author Report Share Posted January 11, 2021 That's an interesting idea. I don't know if the feedback signal could be used as a tach signal. I'll have to try it out! Quote Link to comment Share on other sites More sharing options...
Dougy Posted January 12, 2021 Report Share Posted January 12, 2021 I'll let you know how I go with the IGF signal idea, I'll try and join all 4 together and tap into the original tacho wire. I've changed the resistor in the tacho and it reads (taped into one cop wire) but it's doing something similar as to what happened to you Sushpants. I would like to keep all 4 cop individual if I can so I will try that way and see what happens. (This is a Suzuki tacho but it's similar setup to the Toyota by the looks of it) Quote Link to comment Share on other sites More sharing options...
Dougy Posted February 28, 2021 Report Share Posted February 28, 2021 Hey Shushpants. Could not get the IGF idea to work. I've ended up going to waste spark, freeing up 2 aux outputs so I can run a C.E.L and tacho on the 2 outputs. Having trouble with the tacho still. I've changed the resistor from a 46k to a 1k on the board for now to test it. Tacho does not work wired to the aux output alone, however it does work if I add another resistor, anywhere from 1k-56k in the loom on a 12v switched supply and into the tacho feed wire, also works if I simply add a relay instead of that resistor. I also tried plugging the factory ignitor back in and this makes the tacho sweep work fine also? Currently: ECU aux output spliced into tacho wire--no go ECU aux output spliced into tacho wire + relay pin 86 + 12v switched to 85 pin--works. Or instead of a relay just plug the factory ignitor back in works also KP_JAMES 1 Quote Link to comment Share on other sites More sharing options...
Dougy Posted March 2, 2021 Report Share Posted March 2, 2021 Sorted. Swapped tacho with FP on aux output and put FP on ign output, works with no pullup. KP_JAMES 1 Quote Link to comment Share on other sites More sharing options...
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