Thread: what are the symptoms of a stuck exhaust valve?

Like everybody has said start with the cheap easy things, if it runs fine at idle and then breaks down under load. A lot of things come into play under load. low compression on a cylinder. Electricity taking the line of least resistance(spark plug gap as opposed to breaking over through poor insulation).Trying to get the right fuel air ratio(build up of carbon on the back of an inlet v/v due to leaking v/v stem seal). If you can't isolate the problem the best way is to put the car on a dyno they can tell instantly which cylinder is breaking down( the trick is to find a dyno that won't rip you off) check on the forum for dynos in your area(thats what friends are for)

Originally Posted by DEFENDERZOOK

did you fit a genuine rotor button......

.

Yes genuine. Bloody expensive at over $70. After I bought one, I realized I had a new one lying around.
Also swapped the Diizy cap. no difference.
The plugs are quite new, the disco has 240 K on it, but when I did the heads a coulple of years ago, everything was very clean, as I mostly run LPG so the was no real carbon build up on the valves. The pistons were very clean too.

Strangely enough today, the miss on load has apparently disappeared.
I leading to believe it is an electrical problem.