How important is a strong ignition spark for FE
 

My '93 Civic fires right up every single time - sometimes the instant i turn the key.
Most of the time i don't even hear the starter.
However, the car has always had a very weak spark in several ( if not all ) cylinders .
Power seems weak, but this is an old car with a lot of miles. The car I'd also an automatic.
the distributor is new, the wires and plugs as well.

Will i see a big FE Improvement by fixing the issue ?

What is the condition of the ground wire on the cylinder head. You can a simple test by taking some jumper cables and making four extra temporary grounds then recheck spark.

The ground wire is in great shape, and I even added another ( very small ) ground wire.
Old Mech had suggested looking at the grounds some time ago as well.

What puzzles me is that the car fires right up. If there was a grounding problem, or a problem with the distributor, wouldn't there be some problems starting the car ?

How do you know it has a weak spark?

Well it felt pretty weak when i touched it.


....
....what :D

( Not being a jerk, just my lame attempt at humor )


I tested the spark plugs and when the car is cranked, there is a pale orange spark. Quite weak.
Ideally, it should be a bright blue.

Commercials for Splitfire type plugs would have you believe that some of your fuel is wasted if you have poor spark.
Is there any truth to that ?

If the fuel ignites, then it is on fire...no matter if the spark was weak or not.... right ?

That's what I'd think, unless it was weak enough to cause an occasional misfire.

What is the gap set to? You mentioned that you have good grounds but what about a good supply voltage?

Try it with the engine running. You may see a difference!

Gap is set to factory specs. Supply voltage ....hmmm...well I need to test that.
The distributor ( which has a coil built in ) / plugs and wires are all new.

I'll recheck the grounds again this weekend. I just looked it up, and there are a lot more than I thought : http://honda-tech.com/attachments/ho...-98-ground.jpg

How do you do that ?

Indeed! An extra spark plug perhaps.

You remove one spark plug, lay it on the engine or hold it there (carefully)somehow so it has good ground connection, start the engine and run it, long enough to see what the spark is like. I'm sure there are videos on Youtube that explain it better. :)

Alternatively, there's a device called a Gunson Colortune, I had one years ago.

Close the gap on all the spark plugs by .02-.04 (depending on what stock is supposed to be). On my Fox (prior to going forced induction) I went from the .54 that was stock down to .50. It seemed to have better throttle response at higher rpm ranges. I run .34 now due to FI.

I tested the spark this way, but never let the car actually run more than a second.
It shudders and kicks, and sounds awful, so I always shut it down if it does happen to start on just 3cyls.

Surely running the car on 3cyl is bad for the car !