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Get the spark right

Question : MY 1990 Ford Laser 1.3XL hesitates when accelerating but displays no untoward symptoms when traveling at a constant speed.

I have had the spark plugs replaced and the fuel system checked over by my regular mechanic who has found nothing else wrong with the engine.

I would appreciate your opinion on what else could be causing the problem.

Answer : THE symptoms you describe are typically signs of shortcomings in the ignition system.

The hesitation or lack of power, or even mild jerking are a result of an inadequate spark intensity at the spark plugs, or an incorrectly timed spark.

Since the spark plugs have recently been changed, you could easily discount spark plug failure. You could also discount ignition timing problems for the time being, since this would result in either detonation (engine knock) or back-firing. The latter is a loud popping noise through the exhaust.

The components that are most likely to fail are the high-tension (HT) leads and the ignition coil. Ignition leads do not wear in the true sense of the word, but their insulators will break down over a long period of time; the HT spark leaks through the vehicle bodywork instead of appearing at the spark plug.

Ignition coils can also fail over a long period of time. The internal insulation leaks electrically, resulting in a weak spark at the plugs. The coil is an irreparable item and must be replaced with a new item.

Never mess about with the ignition system unless you are absolutely sure of what you are doing since there are high voltages that can kill.

 
   
 

Sooty spark plugs

Judging the air-fuel ratio

Spark plugs covered with oil

Are 'fancy' plugs good ?

Spark plug won't last

Misfiring spark plugs

Spark plugs poser

Soiled plugs, tired engine

Wrong spark plugs

 

Sump repairs won't last

Not too hot, not too cold

Get the spark right

Glow and new glory

Window into the ( car's ) soul

Clogged plugs

Plug cables

Up in smoke

 

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