Hi Has anyone ever managed to make their own rpm adapter so that the mk2 clocks will work with standard OE management on a 1.8T AGU engine? Mark
i have a theory for agu, if you splice 4 wires with diodes into all 4 wires between the spark unit and coilpacks this should work a mk2 rev counter as they are -ve pulse. basically same as how you have 2 wires with diodes on the 2 spark triggers on a wasted spark setup
apart from jonny's reply which are always good. Why would you bother....when emerald sell them to use the tecko original signal wire, Would not be keen on cutting and splicing signal wires to coils.
I made one with diodes and could not get it to work , i then bought a 034 box worked fine Took the 034 box apart and had some capacitors and other stuff all covered in sealant stuff so could not work out how it worked 100%. But it had more components than i expected. Its not 100% mind , low revs below 1000 is sometimes spikes etc Mines Motec and the feeds comes from the ECU , but i reckon its the same signal as OEM
duff was yours an AGU or an AUM/AUQ? the msd 8920 adaptors also proven to work converting 20v/aftermarket ecu signal to mk2 clocks
If you could see a coil derived signal on an oscilloscope you could probably work out what you need to do. I think the mk1 and mk2 clocks are a current sensing type. 20v tach signal is a 5v square wave.
mine is a bam in mk2 track car but its the sure the coilpacks all operate the same is the important part, i have the early square style ones BTW . Unsure if there is a difference with the slimmer ones for later engines I had success going the other way , taking coil feed into a innovate box for rpm feed for graphing wideband data with rpm and egt etc
ah bam coilpacks are different to AGU, those are + trigger from ecu (I'm pretty sure anyway, looking at the diagrams!) the agu is different in that there is a spark unit between the ecu and coils. ecu triggers spark unit with i assume a + trigger and spark unit triggers coils with a proper -ve pulse which should in theory drive the mk2 rev counter. I had another theory that you could splice an AGU spark unit triggers to the later type coilpack ecu trigger wires and run the -ve pulse outputs to mk2 rev counter, but tbh a revo adaptor would be a bit neater
Ahh i see , yeah thats quite different These adaptor boxes are a bit expensive for what they are , sure you could make one for 5 if you had a PCB or old skool veroboard skills
I'm thinking a circuit similar to this could be made but replace the relay coil with an inductor. I'm going to be trying something myself when the time comes. May also need a resistor in series with the inductor to limit current.
That should do the trick to drive a MK2 analogue cluster from a "TTL level" tacho. I'd recommend building it with the components specified. A coil removed from a relay is good because that's a nice easy source for a high-inductance coil that has a nice safe large DC resistance, so there's no need for an additional resistance to avoid risk of damage to the transistor if it remains on. The 2N5551 is chosen most likely because it has a relatively high VCE, since you can't put a flyback across the inductor (as that would defeat the point of the circuit). So best to use the 2N5551 rather than any garden variety transistor.
^^^As above. On the AGU ME3.8.3 engine control, each coil is driven sequentially and the instruction for independent triggering is given to the 4 channel igniter (N22). As a result of this taking a feed via the 1N4001 method I have previously suggested for wasted ignition systems, from each COP that can have different timing to another cylinder, may not be the best way to measure engine rotational speed. The circuit suggested by tshirt2k and taken from here could be adapted to take the low amplified AGU tach signal like this -> I have created it for the AGU M3.8.3 pin configuration but it can easily be adapted to engines controlled by an E-gas ME7 as well. Relay in question looks like the image below and you only use pins 85 and 86. HTH
why havnt you got a rev counter working, you can get an adaptor for 25 and it take 5 mins hooking it up
