Strange ignition problem?

[Tommo]

I know my cars not exactly a G40, but I could do with some help.

If I am driving along at a steady speed, engine around 3000 rpm, the tacho will suddenly start flicking up to 6 and 7 thousand revs and the car will start to splutter. However if I put my foot down ever so slightly, or let off ever so slightly, it will stop. Its clearly ignition related because the tacho is spazzing out, but its strange how its only at certain loads. It revs clean if you are accelerating hard.

Any ideas?

[PeteG40]

doesnt the tacho take its reading from the coil? so perhaps related?

[Yoof]

I've had this before and it was the coil breaking down.

Get used to replacing ignition components now you're the good side of 200bhp!

[Tommo]

As far as I know the tacho has its own output from the ECU,

Cheers Yoof, I was hoping someone would say they had had a similar problem. I will swap the coil and see what happens, ive been itching to fit a conventional coil for ages anyway.

Its the first problem ive had really, clocked over 8k miles on over a bar of boost now so not doing too bad I suppose.


I might go the whole hog and rip the ECU out, totally do away with the little bugger. Its just I would need some way of rigging my tacho back up.

[Andy]

It could also be the hall sender in the dizzy - though sometimes the plastic disc inside the dizzy that protects the wiring from the trigger wheel breaks up and causes similar symptoms.

You can drive the tacho from the negative side of a conventional coil - the signal from the ECU has the same frequency range.

[Tommo]

Cheers Andy, thats useful info.


I will try the coil for now, it almost makes sence as it seems load related as well as RPM. If all else fails I will stick a set of points on it!

[hayesey]

when I've had a duff coil before it's caused the rev counter to randomly go mental

[hardchargin40]

Would it just be easier to convert to the ford 'edis' system for over 200bhp if we're having so many ingition related issues?

[Tommo]

This is the first ignition related issue I have had, and at the end of the day the coil is 17 years old.

Using the ford EDIS system isnt all that simple, its not much more effort to fully megasquirt the thing (assuming you are on about using the EDIS with megajolt).

[lance]

If all else fails I will stick a set of points on it!

ha ha class!


ill see how mine goes with running a coil pack.

[Tommo]

I wasnt joking about the points! A bit of extra servicing to do but keeps the system simple and functional.

[lance]

thats the point tommo i know you're not joking lol.