I am in the final week before SVA. My rev counter seems to be reading low, when it shows 4000 RPM the engine is screaming.

I have EDIS 4 /MJLJ and an ETB Tachometer on a 1.8 Zetec. The Tacho input is currently connected to one side of the coil pack.
After reading my MJLJ stuff again it mentions I might need a "circuit" consisting of 2 diodes (1N4004) and 1 zener diode (15-18V Zener)

Can anyone confirm if I need this for my set up?
Where can I get these diodes? Maplins??

It there another way to confirm if the tacho is reading correct?

Heeeeelp.


Keith

If I understand things right , connecting to one side of the coilpack will get you half the RPM signals - so half the tacho signal .
The diode circuit is dead easy to make (and cheap , mine cost less than a quid for a triple coilpack one) .

do you have the dip switches set up for the signal of a 4 pot, sounds like you have it set up for a 6 pot,
flick your switches

There is allso a `diagnostic/tacho signal` wire on the edis - have you tried that one ?

Heard of some people using the pip signal wire from the edis too, I made the circuit you refer too but its not too accurate, fine up to about 3000 but then goes out on the low side, so I was thinking about trying the pip route, I am using the standard sierra rev counter though.

Cheers

Rich

My ETB tacho does not have any dip switches.

Also my EDIS pin 11, which i think is the tacho one, does not have a plug wire connected to it.

So should I try the diode circuit mentioned above or try to connect a wire to EDIS pin 11?

pin 2 is the tacho output on edis 4 module connect it to the electronic input (white wire) on the tacho and it should be fine.

* Green Wire– Connect to power source via a 3 amp fuse
* Black Wire– connect to earth/ground
* Brown/Slate Wire– not used in this application
* Red/White Wire–power for the tachometer lamp, connect to a dash lighting power feed.
* White/Black Wire– for use with Electronic Ignition only, connect to the output side of your electronic distributor - please note NOT THE OUTPUT SIDE OF THE AMPLIFIER. Otherwise not needed.
* Red/Blue Wire– for use with contact breaker ignition systems, connect to low tension side of the coil. Otherwise not needed.

[Edited on 28/2/09 by omega0684]

[Edited on 28/2/09 by omega0684]

It will read half revs if connected to one coil supply, the diode circuit should work but i also found it didnt read reliably until I added a resistor to the circuit and then had a problem with a faulty diode causing the engine to cut out.I solved it by connecting to the pip signal on the edis module which works perfectly.
Paul.

I will try the EDIS pip wire on the tacho input tomorrow, when sober.

If this does not work, I will visit maplin and get some diodes and zeners and then try that circuit thingy.

Thanks for replies!

You dont need your tacho for SVA anyway do you - i'd say if it isnt an easy fix just disconnect it and sort it once you have that MAC in your hand

Keith you'll not fail for a dodgy tacho. It just means he'll need to connect his inductive sensor to one of your plug leads for the noise level test at 3/4 revs at full power. Also the same method if it's a cat test. I know ypu'll want it to be working eventually but don't panic in the process.

Agree , if it's not working the tester can't use it or fail the car because of it. Disconnect it until after SVA?

Update - I connected the EDIS pin 2 to the tacho, it now reads OK. Result.

I then jacked up the back and went through all the gears and I am now getting the correct speedo reading for the RPM too (based on the GearCalc software)

Nice to know that IDM on pin two works as well, I'll try that too!!

Cheers

Rich