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Tracking down a "no spark" issue
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Boy9988
Novice
Jan 3, 2010, 3:41 PM
Post #1 of 6
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Tracking down a "no spark" issue
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I have a '93 Honda civic.
What would happen if one was to unplug and replug a spark plug wire out of and back into the distribute cap? That would then result in the engine not starting with no spark.
The ICM, Coil, Spark Plugs, Spark Plug Wires, Distributor Cap, and Rotor have all been replaced.
I can confirm the power is getting to the coil, the rotor is turning, the fuel is getting to the chamber (meaning not Main Relay, fuel filter, or fuel pump), and the ECU is working.
All checks on the distributor, check out. A different distributor was tried and still the same problem.
Any new ideas would be helpful. Thanks
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steve01832
Veteran
Jan 3, 2010, 3:54 PM
Post #2 of 6
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Re: Tracking down a "no spark" issue
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Have you checked injector pulse with a noid light?
Steve
(This post was edited by steve01832 on Jan 3, 2010, 3:56 PM)
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Boy9988
Novice
Jan 3, 2010, 3:59 PM
Post #3 of 6
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Re: Tracking down a "no spark" issue
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I'm not really sure how that relates to no spark, but yes. With the plug out, you can visible see the fuel ejecting from the engine.
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steve01832
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Jan 3, 2010, 4:05 PM
Post #4 of 6
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Re: Tracking down a "no spark" issue
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Here's how it relates. If a car has a no start problem. If it has fuel pressure, fuel injector pulse, and no spark, you track down an ignition problem.
If the car has fuel pressure, no injector pulse, and no spark, you go after a no tach signal problem. If the PCM can't see an RPM when you crank the engine over it doesn't know we are trying to start the engine. Therefore the PCM will not fire the injectors. So now we would start to look at a crank sensor problem, or in the older days, a distributor pick up problem. That's why we always need to know what the engine has and what it doesn't have when we crank it over. These tell us what diagnostic road to go down.
Steve
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Boy9988
Novice
Jan 3, 2010, 4:16 PM
Post #5 of 6
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Re: Tracking down a "no spark" issue
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Well what happened first is we had a low spark problem (which we think we fixed after the fact with the spark plug wires). But the car stared for us. When we went to set the engine timings, the car would begin to spudder when we pulled the trigger. So we pulled the the connector off the spark plug cable and just plugged it back in. Then the car died and has never sparked since. We have been working on this for two weeks and from what we can tell, its deffinatly something outside of the distributer and probably electrical (or some damned sensor). We are Mechanical Engineers, so the engine stuff is fine for us, but we aint no damn electrician. We have done all the "usual" things people have mentioned to us, so we are now looking for some outside the box, more "unusual" types of issues that would cause this.
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Sidom
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/ Moderator
Jan 3, 2010, 4:53 PM
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Re: Tracking down a "no spark" issue
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This sounds very similar to an Acura I had a few weeks back that had a bad coil that took out the ECU.
ECU failures on Hondas are rare but it does happen.
I don't have all the info handy but here are a couple of quick checks you can run to see if you are getting an ign signal & the dist is capable of producing spark.
On the 8 pin connecter to the dist there should be 7 wires, 6 are paired & one is by itself. It should be green/yellow, this is the signal input to the ICM. If you have a scope, back prob the wire & while cranking you should have a square wave pattern (basically it's just on & off). That would tell you the ECU is trying to control the ign. You could probably use a dvom and look for a fluctuating reading but that's not real accurate for this kind of test. The other wires are inputs for the ECU. The crank, cam & tdc sensor. Each has 2 wires and produces an a/c sine waves the ECU processes to determine proper spark timing....
With that 8 pin connector disconnect but all other connectors hooked up. Take the cap off the dist & hook a spark tester between the coil output terminal & ground. With the key on, get a test light & hook it to ground and with the probe, quickly tap the terminal of the green/yellow wire of the 8 pin connector going to the dist. This should create a spark and would let you know that the coil & ICM are good & capable of creating a good spark. It's called a "tap test" and will help you rule out or confirm a bad part........
All this is going off the top of my head, for exact specs & amplitudes I would have to get it from my data base at work.......
(This post was edited by Sidom on Jan 3, 2010, 4:57 PM)
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