Bouncing Tacho

[chris1972]

This happens to me from time to time. I have no idea why. I heard that it may have something to do with Magnecore leads/ king lead?

What is the solution?

[blitzracing]

Do you actually have Magnecores? If you do you need to increase the lead resistance in some way, be it resistive plugs, resistive plug shrouds, or a normal resistive king lead- well its a good place to start anyway.

[chris1972]

I do have them, cheers for that. Any recommendations on a king lead? Does it need a specific resistance value?

[blitzracing]

The whole business of lead resistance is pretty vague at best- the issue is the path between the coil and the plugs does vary, so will the resistance, so its not a precise science. Just try a bog standard carbon lead and see if it works, it wont cost much.

[chris1972]

Okay, cheers for that!

[jojackson4]

If you get to the bottom of it post as mine is like the queen wavering

[CHEF_GOLF]

Mine does too. But it always has. I have had some custome solid copper ht and king lead made and had the resistors taken out of the shrouds and replaced the plugs with un resistored ngk for a cleaner spark. But this has made no change to the problem

[chris1972]

I haven't got around to looking at it yet. As for taking the resistors out, if you read Blitz's post, it is the resistors that are meant to help alleviate the problem.

[ChimpOnGas]

I was recently told a fix for this is to run the tacho feed wire through the switching coil of a common relay.

Not tried it myself.

[blitzracing]

That will be to filter out the extra spikes you get on the coil primary from low resistance leads. The relay coil will act as a choke.

[ChimpOnGas]

blitzracing said:

That will be to filter out the extra spikes you get on the coil primary from low resistance leads. The relay coil will act as a choke.

Well apparently it works, it's a cheap as chips fix too.

Can you confirm the wire I need to intercept Blitz?

White?

If you can get back to me quickly I'll try it this morning as I'm with the car doing the last bits of prep for my big trip.

We set out early Monday morning

[Sardonicus]

ChimpOnGas said:

I was recently told a fix for this is to run the tacho feed wire through the switching coil of a common relay.

Not tried it myself.

Its a bit more than that Dave especially for the after market ECU crew's waving Tacho's YHM

[ChimpOnGas]

Sardonicus said:

ChimpOnGas said:

I was recently told a fix for this is to run the tacho feed wire through the switching coil of a common relay.

Not tried it myself.

Its a bit more than that Dave especially for the after market ECU crew's waving Tacho's YHM

Cheers Simon, You also have mail.

I'm up for trying the alternative solution for the after market ECU crew