Tachometer

Josh · backyard mechanic Joined: 04 Oct 2001 Posts: 602

If the needle on the tacho jumps up and down down it meen the points arnt working propley or does it meen there is another problem like the leads? By the way the single lead for the tacho goes to the coil as normal... I'm just trying to pin point a problem

cool gem · rice boy Joined: 16 Apr 2002 Posts: 39

Probly just a dicky conection ahy mine dose that

Josh · backyard mechanic Joined: 04 Oct 2001 Posts: 602

na man
coz when it miss fires the needle drops
The needle doesnt drop for no reason...

cool gem · rice boy Joined: 16 Apr 2002 Posts: 39

how about fixing the missfire!

Josh · backyard mechanic Joined: 04 Oct 2001 Posts: 602

That what I am trying to do! I need to find out if it's the dizzy cap, leads, rotor button, points or coil...

Gene FJ20DET · Posted: Tue Apr 16, 2002 10:34 pm Post subject: Re: Tachometer

i recon the coil try an old one or something to test it. similar thing happend to me.
gene
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Gemini Driving Yobbo · petrol head Joined: 26 Feb 2002 Posts: 3897

ive got the same problem but its with my spedo what do i do??????????????

TXcoupe · petrol head Joined: 05 Oct 2001 Posts: 1675

i seriously think its the points mine did that aswell. if you have a multi meter try the leads for there resistance

Josh · backyard mechanic Joined: 04 Oct 2001 Posts: 602

It has to be the points does it?!?!?!

Because the tacho gets it signel from the points. Any problem after that wouldnt show up on the tacho... ???

Woz · tinkerer Joined: 05 Oct 2001 Posts: 126

this is something that i posted for some other dude a while ago...hope it helps Smile

-woz

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if your tacho is bouncing down to 0 while this is happening, there must be a problem with the ignition, ie. it cutting out, causing spluttering and the tachos bad readings.

try replacing, one at a time if ya want:
-points
-red/black wire between coil/points
-coil
-balast resistor
-spark leads
-dizzy cap
-dizzy rotor
-spark plugs

also, there could be a slight chance that the wire leading from coil/points could be shorting out on an earth somewhere (even the wire that leads to tacho from this) so check these too.

id place my money on the coil or fractured ignition wire tho Smile

Josh · backyard mechanic Joined: 04 Oct 2001 Posts: 602

Why does everyone think the problem is with the coil??? Is it common for a coil to wear out?

matey_mate · tinkerer Joined: 23 Oct 2001 Posts: 165

do a burnout

Racegem · backyard mechanic Joined: 30 Jan 2002 Posts: 987

Usually if the speedo cable is about to let go, it will cause the needle to jump around.

Yonnee.

Racegem · backyard mechanic Joined: 30 Jan 2002 Posts: 987

How old are the electrical bits in your ignition system?
Without knowing how mechanically/electrically minded you are I don't know simply to explain it. The tachometer is only reading what the negative side of the coil is telling it, and the negative side of the coil includes the points. Try the points first, it's the cheapest and easiest, and if they're old enough, probably need doing anyway.

Yonnee.

Getafix · tinkerer Joined: 16 Jan 2002 Posts: 146

Try pulling out the plugs and inspecting those, re-gapping if necessary etc. Mine used to misfire, and i took out the plug on the #3 cyclinder and it was caked in shit, burnt oil i assume. so i took it out, cleaned it, whacked it back in, good as new. however i have to repeat the process every 2 months otherwise it'll miss again, i think it's a crap valve stem seal and i havnt had time to get it fixed yet. Also a Q of my own, sometimes the valves tap under load (i.e. up hills etc) usually when the car is warmed up, any ideas (checked the timing and dwell, new dizzy cap, newish plugs)

-dave