mos 1 Posted July 20, 2006 Hi, my rev counter has developed a mind of its own about 3,000rpm the needle will start dancing around sometimes it will race around as far a 5,500 rpm but usually it will only osilate over a 1000rpm so part of the rev range. this is an intermittent fault occuring about 20-30% of the time but its very annoying, i have tried a couple of spare dash clock sets, a couple of coils and a couple of ignition applifiers i have lying around but to no avail!!! has anyone else ever had this fault? i am stumped, any ideas anyone,could it be a wiring fault and what is the cause likely to be? where does the signal to the rev counter actually originate, is the dizzy, is it the coil or is it the ignition module? i am not the world greatest auto electricitian but i am reasonably competent can some one steer me in the right direction on this one thanks Share this post Link to post Share on other sites
Jonmurgie 2 Posted July 20, 2006 More than likely a dodgy earth.. check the earth strap on the gearbox and also give the brown multiplug a clean Share this post Link to post Share on other sites
jackherer 543 Posted July 20, 2006 More than likely a dodgy earth.. check the earth strap on the gearbox and also give the brown multiplug a clean the tacho signal doesn't go through the underbonnet brown multiplug... checking earths sounds like a good idea though. Share this post Link to post Share on other sites
Jonmurgie 2 Posted July 20, 2006 Oh, well I always think that brown plug shoudl be checked no matter what the problem is Share this post Link to post Share on other sites
Higgy 0 Posted July 20, 2006 Oh, well I always think that brown plug shoudl be checked no matter what the problem is Someone recommended that you get the doctor to check your brown plug every so offen. Oh that another brown plug. Yep, the heats getting to me. I'm getting cabin fever here Share this post Link to post Share on other sites
mos 1 Posted July 20, 2006 (edited) had a look tonight and the dizzy wiring has been tampered with, never noticed this before and i cant really think why anyone would do this but for whatever reason the three pin connector plug that normally comes from the dizzy and connects the dizzy to the main loom has been removed and only two of the wires have been used to hard wire the dizzy to the loom, what do the three wires actually do and the fact that one wire appears to have not been used have any bearing on my problem with an erratic rev counter?! does the dizzy feed the rev counter in any way? or are they completely seperate? help! Edited July 20, 2006 by mos Share this post Link to post Share on other sites
pug309twin40s 1 Posted July 20, 2006 the rev counter gets it feed from the ignition coil. wire 112 usually. my goodwood was doing this. unfortunetely i didnt get to solve this before the engine died. try changing the ignition coil for another if you have a spare. Share this post Link to post Share on other sites
mos 1 Posted July 20, 2006 tried changing the coil (twice) and the ignition module also twice with the spare ones i have over gained over the years the fault is still there. the only major component on the ignition i haven't tried changing so far is the dizzy as i do not have a spare but that said i think a friend has one that i could try. but having seen the tampered with dizzy wiring its got me thinking that this is where the problem may be. but if the dizzy has nothing to do with the rev counter i would be barking up the wrong tree. does anyone if the dizzy is connects to the rev counter in some capacity? what the three wires to the dizzy actually do? and should the third wire actually be connected on a twin carb install? Share this post Link to post Share on other sites
