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Author: Subject: Help - Rev counter reading low
Slater

posted on 28/2/09 at 09:56 PM Reply With Quote
Help - Rev counter reading low

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





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clairetoo

posted on 28/2/09 at 10:01 PM Reply With Quote
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) .





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tomgregory2000

posted on 28/2/09 at 10:03 PM Reply With Quote
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

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clairetoo

posted on 28/2/09 at 10:04 PM Reply With Quote
There is allso a `diagnostic/tacho signal` wire on the edis - have you tried that one ?





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RichardK

posted on 28/2/09 at 10:16 PM Reply With Quote
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





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Slater

posted on 28/2/09 at 10:16 PM Reply With Quote
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?





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omega0684

posted on 28/2/09 at 10:25 PM Reply With Quote
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]

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paulf

posted on 28/2/09 at 11:12 PM Reply With Quote
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.

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Slater

posted on 28/2/09 at 11:23 PM Reply With Quote
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!





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Paul TigerB6

posted on 1/3/09 at 02:05 AM Reply With Quote
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
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omega 24 v6

posted on 1/3/09 at 10:55 AM Reply With Quote
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.





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rusty nuts

posted on 1/3/09 at 11:25 AM Reply With Quote
Agree , if it's not working the tester can't use it or fail the car because of it. Disconnect it until after SVA?
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Slater

posted on 1/3/09 at 06:16 PM Reply With Quote
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)





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RichardK

posted on 1/3/09 at 10:32 PM Reply With Quote
Nice to know that IDM on pin two works as well, I'll try that too!!

Cheers

Rich





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