?Ignition problem

[Philip Hadley]

It's just one thing after the next at the moment!!!
I was out in the Cappo today when the car started mis-firing quite badly and the Speedometer & Rev Counter indicators started 'flicking' wildly backwards and forwards. Has anyone any ideas as to what might be causing this. My initial thoughts would suggest some kind of ignition problem. I have just been out and about tonight (very local) and would you believe it she's running like a swiss watch!! I would value your comments.

[Murray Betts]

I'd start with the easy stuff first.

A quick glance at the wiring section in the manuals suggests that there's a 15A fuse for "ignition coil/meter". I'd pull all the fuses and check the condition of the contacts/blades. Clean up or replace as necessary. The contacts at the fuse blades can deteriorate with age.

The majority of electrical problems are to do with connectors, and I'd include fuses in with that. It might be worth getting some aerosol contact cleaner which contains a lubricant, places like Maplins have it or try online suppliers.

[Adrian Furniss]

I agree with Murray, an electrical connection would be the first suspect.

In addition to Murray's suggestion:

• check the condition of all three main fuses (under the bonnet, front nearside, top of wing)
• make sure the battery connections are clamped on properly

[Philip Hadley]

I had a recomended Vehicle Electronics Engineer (Mobile) come to my house this morning to assess the Cappo. After he 'popped' open the bonnet he immediately noticed that the Lamda sensor plug was not connected to its corresponding terminal!! (See recent work I've had done - Head Gasket/Exhaust Manifold etc..) He thought this was the probable cause of the mis-fire, but could'nt explain why it had only started mis-firing recently - the work was completed 4 weeks ago and I've been driving it around ever since. As for the Rev Counter spiking, he suggested some new HT leads, because he couldn't find any electrical faults.

I would of thought that if the Lamda sensor hasn't been connected after some major maintainence it would of manifest itself alot earlier than 4 weeks!! Does this make any sense to anyone?

[Murray Betts]

I would at least expect a "check engine" light with the lambda sensor disconn.

Don't know what the default condition would be as far as fuelling goes, for limp-home it's normal to use a more or less stoichiometric map, temperature corrections should still apply for cold starting etc. Higher loads and speeds go "open loop" anyway so don't use the lamba sensor feedback so it should run OK at these conditions (I think it's open loop above about 4000rpm).

The meter signals won't be affected by HT leads breaking down, I still suspect an intermittent connection on a common feed, most likely the power from a common fuse/relay. Could be that generally searching round and moving connectors etc has effectively "fixed" it. Fingers crossed.