bouncing rev counter

[chrisdurham]

hi guys,

a fe days ago my rev counter started going haywire - it bounces about all over the place. when sitting at a steady speed it wavers a good few 500 rpm

i checked the main earth straps last weekend.

any ideas?

[The Surveyor]

I can remember that this can be related to the coil breaking down or something on the low-tension side of the ignition system. My old Chimaera had the same and that was cured by a service which included new ignition parts.

Paul

[chrisdurham]

ive just replaced everything but its not helped - eg, plugs, leads, extenders, cap and arm.

i do seem to think it started after i changed the alternator....

i never put those little surpressors back on the new alt - could they have caused this?

[The Surveyor]

I wouldn't have thought it was related to the surpressors, they are for radio interfearance IIRC.

Try cleaning the connections to the altinator if that's what triggered it initially, or if you still have the old one, just swap it back and see if that stops the bouncing rev counter.

Paul

[blitzracing]

Magnecores?

[big geoff]

ignition amp

[chrisdurham]

hi guys,

old alternator was shorting battery to earth so cant swap back. I cleaned up all the connections when I fitted it.

I have std bosche leads. it done it before and after the plug/lead/extender swap.

[Meatball]

My rev counter played up before the 100 amp fuse popped

[chrisdurham]

mines is a 93 model with no fuse

[Ozstyle]

It could be the new king lead (coil to dizzy cap). I had this problem when I replaced my HT leads, after a checking a few threads, I changed the king lead back to the old one and fixed the bouncy tacho needle (ETB instruments). The old king lead had a lot more resistance than the new one, eventually replaced with a genuine rover item which had higher resistance compared to new non oem king lead.