Project84

My car was getting more and more difficult to start and now it won't start at all. I put the timing light on the spark plug wires and verified that there is no spark. I pulled the plugs and they are soaked with fuel and blackened with crap, hence the reason it won't start.

My question is this: Where does the coil discharge its energy when the plugs aren't working correctly? From what I understand, the coil has a primary winding that is energized with current from the battery. The secondary winding is wrapped around the primary, and when the current to the primary is interrupted, it cause the magnetic field to collapse, inducing a current into the secondary coil, which is discharged through the spark plug wire and through the spark plug electrode, where it jumps to ground, which is the engine block in automotive applications.

So, where does the spark go when the plugs are fouled?

shawn1985

in an electronic ignition system as in normal or even rotary engines there are companion spark plugs. if you look at an a 13 B engine or even a chevy 1500 you will see that there are companion spark plugs/cylinders. with computer controlled or electornic ignition the computer will determin the spark by energizing the coils. now in basic electricity when a current is produced it had to complete the circuit to ground. like you said. except it completes the ground by going through the companion spark plug to be grounded or through the block depending on manafacture. the whole process is really complicated. it took the better part of a day in class for the teacher to explain it. but electricity doesn't know the difference between air and dirt. the only difference is the amount of resistance. in a gunked up engine the path of least resistance will be the path taken by the voltage from the coil. the gunk encased the plug making it impossible for there to be a gap for an arc to form. so instead of making an arc it simply grounded through the gunk into the companion cylinder or ground. if i didn't make any sence i'm sorry but the basic point is it always gets to ground some how.

Project84

What?

shawn1985

spark plugs with dirt/grime/oil, voltage from the coil will travel trough that stuff without creatin a spark to ground completing the cricuit as we call it. therefore not combusting the gas. sorry didn't mean to confuse you earlier

Kenteth

When the plugs are fouled, all the carbon and build up and crap add resistance. It takes a harder push of e- to get through the carbon and crap... thats where the spark's power is being used... getting the e- flow to the eletrode and across to the other electrode.


so basicaly, the spark discharge goes to teh same place it always would, but having fouled plugs means its such a pita for a spark to occur that it occurs and we can't see it (flows directly through all the crap on the plug), or somethings foobard.

Want to test? Put your fingers on the eletrcrode, if the coil is trying to discharge, you WILL know about it.

Project84

ok, so if the spark is going to the same place, it is still traveling through the spark plug wires to get to the plug. Why doesn't my timing light show this when I hook it up to the plug wires?

Kenteth

If the spark plug doesn't fire in the form of spark, I don't know that there will be enough of a em field in the plug to signal the timing light. The added resistance slows the **** out of the e- flow(errm.. well makes it smaller). The spark is no longer instaneous, but rather takes a while to spread across the fouled carbon. The more resistance it has, the slower (smaller anyhow) the e- flow, the less EM field will instaneous be present at the plug wire... And if theres not enough of an EM field to signal the timing light...

Project84

ok, I'm going to go buy new spark plugs.

j9fd3s

iTrader: (3)

its either gonna do 2 things, not generate enough power to fire at all, or its gonna arc to ground at some strange place

Kenteth

Checkers had a new box of bureq9s when i was there last week Anyhow, I just bought all nines since they had a new box and its been fine.

The one short chubby kid thats worked there should be able to help, hes the one taht always gets the plugs and i've explained it to him before. You'll know its him when he has to climb up the rack to reach the bureq NGKs that are up there a ways.

Technicaly yeah, though my point is it doesn't have to create a spark to still use up the e- flow, carbon is conductive... However, it could find a place to arch anywhere from the coil to plug. Thoguh if it were firing at the block on the plug, it should still pull enough of an em field to fire the timing light. If it fires at the coil though, that will be slightly different. I'm, not sure if you put the timing light lead at the coil if it will pick it up or not... Interseting way to find sparks though...

shawn1985

try using gm top engine cleaner for your engine to clean it out whats the use of buying new plugs if its only goin to get messed up again that stuff works awsome isn't a timing light used for a distributer? why would you use it on spark plug wires?

shawn1985

use gm top engine cleaner to clean your engine. might as well because if you don't your only going to mess up the new plugs u put in. why would you use a timing light on plug wires i thought u used it to time a distributer on the counterweight on the flywheel

Kenteth

Alot of timing light signals clamp on to the sparkplug wire and catch em fields to know when to discharge the flash tube. Infact almost all of them do it this way... Hardwiring a timing light for 3 minutes of use is teh ghey.

shawn1985

ok like an ignition scope pretty much

Kenteth

An ignition scope is stupid complex compared to a timing light. All a timing light does is feed a capacitor and then listen on the signal for when to discarge the signal into a xenon (usually) flash tube.

Does the EXACT same thing as the strobe light. Just instead of a timed discharge signal by a variable resistor, the discharge signal is the EM field craeted by the sparkplug's spark (technicaly the em- movement in the wire too).

So when the sparkplug fires, the em- field disapates from the plug/wire, the timing light lead sensor senses the em field, and tells the capacitor to discharge into the flash tube. The flashtube fires and strobes. If you've got it pointed at the main pulley, you'll be able to see the timing marks on the pulley, and you'll know how your timing is set.

RotaryEvolution

iTrader: (30)

DP V

RotaryEvolution

iTrader: (30)

nope, only some newer cars `90-ish up to current use paired coils, FCs do not use paired coils, though the trailing coil is one unit it is still not a paired unit. an example of this would be a 95 neon 2.0L DOHC has 2 coils, each coil controls spark to 2 cylinders, if a coil fails it fails on 2 cylinders, if a plug fouls on 1 cylinder it affects its paired cylinder as well.

if a plug fouls in an FC the spark can either go through the boot/wire to ground if it can force its way out of run in a continuous loop back through the coil dissipating in a matter of milliseconds, it does not necessarily have to go to ground to diminish.

RETed

It's called "wastespark".
The FC does use a wastespark'd leading.


-Ted