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About quattro

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  1. Tacho issues

    I am measuring the voltage at the 86 terminal on the relay with a basic DV Voltmeter. I realise that I am measuring pulses and won't get an accurate reading of voltage, but if one circuit is rapidly jumping around from 0.5V to 9V, and the other is a constant 5.4V, then something is wrong. I suspect the problem is with the bouncing one. I am either using the 1K resistor and 2N2222 in the ECU, or a circuit that I have made using a 1K resistor and a 2N5551 transistor. When using my circuit, I just bypass the ECU circuit and connect directly to JS3. With the home made circuit, the tacho rises when the car is revved, but is not steady. The relay doesn't buzz at all. I am aware that my testing equipment is nowhere near good enough and I'm not entirely sure what to test for anyway, so have now found someone to test the entire thing, ECU, added bits and my home made stuff. Let's hope that sorts it When you said earlier that the MS settings looked fine, did you mean the 7, 1 and 0, or the 5, 2 and 55? Cheers Richard
  2. Tacho issues

    Megasquirt support forum (MSEXTRA). It does look like there is something wrong with the added circuitry in the ECU, as the voltage is bouncing around inside it. My circuit is not opening the transistor fully as I'm only getting 5.4V at the -ve side of the relay? I'm going to try and whack it with a hammer later Richard
  3. Tacho issues

    I was advised to post on other forums Garry, and Dave has been very helpful. The third forum haven't answered yet so I'll just stick with the two for now.
  4. Tacho issues

    Hi Bowie. It worked perfectly prior to the installation of the EFI. Also, I do have another tacho, albeit from a 4 cylinder P6 (still RVC), and when I fitted that it bounced around like the 8 cylinder one. I will try that again now I have got somewhere though, I am open minded about the cars original wiring. Richard
  5. Tacho issues

    Out with the multi meter - right with this circuit the relay buzzes intermittently. With the engine running, the voltages are +ve side of coil (85)- 14.3V, -ve (86) - jumped from 0.5V to 9V and all points in between. Voltage at JS3 jumped around from 1V to 4.5V. I disconnected the orange wire, and then connected a patch wire to it, then clipped the other end directly to JS3 with a crocodile clip. This basically bypassed the circuit in the ECU without me having to remove/cut anything . I then connected this to my circuit board like this Now, the voltages are (85) - 14.3V, (86) - 5.4V (pretty much constant), JS3 4.5V, base of 2N5551 0.7V, resistor in 4.5V, resistor out 0.7V. All of these voltages are fairly constant. The tacho does now point in the right general direction but still waves around a fair bit. It's better, but not yet right, and not accurate enough to use. There is not enough voltage to fire the relay, so no buzzing at all. All the above readings are at tickover (750-800rpm). So, more from intuition than electronic knowledge, I would say there's something amiss within the added circuit in the ECU - although any opinions would be greatly received
  6. Tacho issues

    I would be using JS3 to run through this :- So, not directly to the coil. The firing of the relay is intermittent, you can hear it with the switch gear in there. It makes no difference to what the tacho does, whether I use the relay with the switch still in there, or the one I have stripped out. I have three relays in all and they all do the same. When the relay is switching on and off (buzzing), the tacho works correctly, so I am thinking the circuitry somewhere isn't up to firing the relay. I will try to get a voltage at both ends of the relay when the engine is running, and see what is happening there, but am short of time at present (I'm supposed to be working ) Richard
  7. Tacho issues

    Right tried wiggling everything, and the car engine died. So managed to start it again and took it for a short drive where it kept dying on me, so back to the workshop and tried wiggling everything again. Checked every plug, pin, wire, connection, nothing. So went and got some petrol next job after the tacho is the fuel gauge. So is the 2N2222 up to the job? - I am not good enough at soldering to try to remove the 2N2222 and replace it with the 2N5551 in the ECU My soldering skills look like I have used an arc welder. Or, would it be sensible to cut both the red and orange wires in the ECU and solder them together, to bypass the circuit in there, and then have a wire direct from JS3. Then run that through my circuit. Also, I have googled the output system and found that the settings may be wrong . I have changed the figures in the boxes from 7, 1, and 0 to 5, 2, and 55, which should apparently start the feed from JS3 at 500rpm, stop it if it gets down to 300rpm and give it a higher limit of 5,500rpm. This made no difference at all so does anyone know if these figures are correct? Thanks in advance Richard
  8. Tacho issues

    I'll give that a go tomorrow. I will also get the multi meter out and test the circuit along its entirety whilst it is running, hopefully find an intermittent voltage somewhere. I'll be glad when I've had enough of this
  9. Tacho issues

    I am a retro sort of chap The buzzing on off is not regular at all, it's more of a sh... ermm fits and starts sort of thing, like it's trying to work but isn't quite there. Richard
  10. Tacho issues

    I've added a relay and now have this I took the switching gear out of the relay as it wasn't needed but this meant I couldn't listen to it to check it was working correctly, so I went out and bought a new one. Started the car and the tacho sat at 750-800 rpm which was right but only for a few seconds and then it dropped, then started again, then stopped, and started again, etc. I got out of the car and listened to the relay, and it buzzed, then stopped etc in line with the tacho, so if it buzzes, the tacho works. I can only conclude that the signal switching the relay, from the ECU, is not switching it reliably. I take it from the diagram, that the transistor is like a switch which is turned on and off by JS3 after going through a 1K resistor, and this then allows the current to pass through to earth, thereby firing the relay. So any ideas why this intermittent feed is happening? Thanks in advance tachbounce.wmv relay.wmv
  11. Tacho issues

    So, use the circuit he added as part of the tacho fix circuit? I'll give it a go tomorrow Richard
  12. Tacho issues

    Hi Ian The tacho is the RVC type and worked with the dizzy and coil set up. I have a spare tacho, again an RVC type but for a 4 cylinder car. I have changed to this one to check and it does the same as the V8 0ne.
  13. Tacho issues

    Hi lo-fi It's a P6 Rover and yes, it used to run from a single coil and carbs. I have used Quagmire's circuit and it doesn't work, a Tachfix doesn't work, the four 1N4004s circuit works up to 1,300rpm. All of these are from the megasquirt manual and are for the single coil, high voltage tacho. I have another tacho for a 4 cylinder P6, and the various fixes above, do the same with that. The circuit I have posted in my last post is one that was added to the ECU when the output wire was fitted. This is inside the ECU. I was remarking on the similarity of this to the circuit used by Quagmire. Richard
  14. Tacho issues

    This appears to be what has been added - looks familiar somehow I wonder of I can just add a relay to this
  15. Tacho issues

    Tunerstudio is showing JS3 I am just making up a small wiring diagram for the circuit he has added. I only have a photo of the top of the original, but hopefully it will do