Useless rev counter

[ChilliWhizz]

It can't keep up with the engine revs if I floor it in first and second, it's all over the place, Any ideas chaps?

[TV8]

A new situation or have you changed the leads or plug extenders?

[ukdj]

It's a known problem and can be caused by interference as Graham has suggested, the "fix" is to run the signal wire to the gauge through a relay coil to smooth it out.

[ChilliWhizz]

Thanks guys, its been like it for a long time, in fact since the engine was rebuilt, I've lived with it but it's now becoming annoying Changing up is a guess based on noise and how it feels, peak power is at 6100rpm but I never know if I've hit that or gone beyond it... soft limiter at 6.5 and hard limiter at 6.7K....

[blitzracing]

Magnecores?

[ChilliWhizz]

No, not sure what the make of the leads are, fitted by Rob when he rebuilt the engine...

[Sardonicus]

Chilli are you running the Lucas?

[Hoofa]

If it's aftermarket ecu ? I had this with an emerald until I had the counter modified by speedy cables to read the ecu signal correctly

[roseytvr]

Chilli,

Worked for me when I changed over
http://www.ms2tuning.com/products.html
Are you joining us on 15th at Bedford?
Ian

[carsy]

Yep thats what I used or emeralds equivalent.

[Sardonicus]

Never had any issues using a signal conditioner from my MS to the tacho no waving needle or erratic anything and at least as good as stock

[Dr Mike Oxgreen]

blitzracing said:

Magnecores?

Interesting. My car has had blue Magnecores fitted since I had it, and the rev counter has always waved around fairly wildly when 'blipping' the throttle. It settles and reads sensibly when the engine is at steady revs though.

I always assumed it was "TADTS".

So are my HT leads to blame?

[ChilliWhizz]

Guys thanks for all the replies, I'm running MS2 & wasted spark etc etc... Ian's link has led me straight to Shaun's website and the 'Tachfix' Silly me should have mentioned it to Shaun when he last mapped the old girl...

Ian, I'm away from this weekend but probably only for 10-15 days so should be back for the 15th - I see it's a Monday Might stay at my daughters on the Sunday night she's near Huntingdon... Thanks for the heads up

Cheers Chaps,
Chilli

[blitzracing]

Dr Mike Oxgreen said:

Interesting. My car has had blue Magnecores fitted since I had it, and the rev counter has always waved around fairly wildly when 'blipping' the throttle. It settles and reads sensibly when the engine is at steady revs though.

I always assumed it was "TADTS".

So are my HT leads to blame?

They are about the worse you can fit- they are designed for race use, not a road car, so the lead resistance is very low. The effect is the spark discharge is much more rapid and intense than is needed, and the down side is it produces bigger spikes in the coil primary as it discharges. Its these spikes that the Rev counter reads, but there should only be one per spark, not a series of them that low resistance leads produce. This will make the RPM signal very erratic. The easiest fix if you want to keep the magnecores is to put more resistance in the HT system, either by using a normal carbon king lead , resistive plug shrouds or plugs

[Dr Mike Oxgreen]

Thanks Blitz. I have no particular allegiance to the Magnecores, and have often considered changing them as they're probably quite old.