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PostPosted: February 28, 2020, 12:26 pm 
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Joined: July 6, 2008, 12:48 am
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Location: Amador County, CA
Wife's CRV died the other day, I was driving. It quit, then picked back up for a few revs, then died completely.

I will spare you everything I've checked but the bottom line is that there is no spark until the plug is removed from the engine. So no spark when the plugs are under compression.

Works fine with the plugs out. I see no issues with the cap/rotor/coil visually.

I read that coil and ignition control module (ICM) are common failures on these cars. I am imagining the system as this (I am probably wrong here so please correct me): The coil provides the punch for the spark and the ICM only tells the coil when to fire. So if we have spark outside of the motor then the ICM must be fine. Maybe coil has partially failed and cant provide enough juice when the plug is under compression? I hesitate to throw a coil at it without being able to verify that it is faulty.

Some pictures...


Attachments:
cap.png
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cap off.png
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cap off 2.png
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soot.png
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meter 1.png
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meter 2.png
meter 2.png [ 1.31 MiB | Viewed 3837 times ]
divots.png
divots.png [ 716.28 KiB | Viewed 3837 times ]
spark.png
spark.png [ 532.27 KiB | Viewed 3837 times ]

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PostPosted: February 28, 2020, 12:47 pm 
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Joined: October 19, 2012, 9:25 pm
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Location: Summerville, SC
Strong spark with the plug removed? If not, I'll bet on the coil being bad.

I had a similar problem with the 2 stroke in the A Mod. Spark with plug in the air, wouldn't consistently light off the cylinders though. It turned out to be a bad MSD box.

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PostPosted: February 28, 2020, 2:04 pm 
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For that low resistance reading, subtract the reading you get when measuring probe tip to probe tip to get the real measurement. Typically probe leads will read between 0.1 and 0.3 ohms by themselves. That would mean that your readings are well within spec.

You are getting a hot spark in free air as shown (no wires, no rotor, no cap, have you checked your plug wires). A spark will jump between the easiest path. The soot appearance on the coil where the molding sprue was might mean that there is a fault that might be arcing over to the casting. FYI, the required distance to arc under compression might be 1/10th vs in free air. That means if there is a bare conductor with a distance of <.4", it might well spark outside rather than at the plug in the cylinder.

I have used clear nail polish to insulate where a fault might be to prove or disprove a diagnosis. I would clean that sooty area on the coil and coat it with a few coats of nail polish to see if this is your problem. If it runs, then replace it. The nail polish trick is a diagnostic tool. It is not a permanent fix.

You could also look at that area during cranking without the screwdriver. If it is arcing. If so, then, you know what to do. I have had bad rotors also, where the rotor internally shorted to the shaft. Not in a CRV, but another make.

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PostPosted: February 28, 2020, 2:21 pm 
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Have you checked the supply voltage to the coil? Could be that with plugs in, voltage is getting pulled down below threshold voltage for spark due to extra load on starter which leads to next thought. Check to make sure you have solid ground to engine block. I fixed a problem on a neighbors car that acted almost exactly like this and the ground strap was corroded on one end.
Happy hunting!

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PostPosted: February 29, 2020, 10:47 am 
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Joined: March 19, 2011, 10:22 am
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I vote for faulty coil also. Too bad coil is in distributor. When I suspected my bad coil on Chev truck I waited until dark, cranked engine to start and watched the spark jump across/around coil body instead of though HT wire.

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PostPosted: March 2, 2020, 11:10 am 
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Joined: July 6, 2008, 12:48 am
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Location: Amador County, CA
It was the coil, thanks for all your comments! You guys made me confident enough to go buy a coil.

TooBusy wrote:
Strong spark with the plug removed? If not, I'll bet on the coil being bad.

Nice job, thank you!

rx7locost wrote:
For that low resistance reading, subtract the reading you get when measuring probe tip to probe tip to get the real measurement. Typically probe leads will read between 0.1 and 0.3 ohms by themselves. That would mean that your readings are well within spec.

You are getting a hot spark in free air as shown (no wires, no rotor, no cap, have you checked your plug wires). A spark will jump between the easiest path. The soot appearance on the coil where the molding sprue was might mean that there is a fault that might be arcing over to the casting. FYI, the required distance to arc under compression might be 1/10th vs in free air. That means if there is a bare conductor with a distance of <.4", it might well spark outside rather than at the plug in the cylinder.

I have used clear nail polish to insulate where a fault might be to prove or disprove a diagnosis. I would clean that sooty area on the coil and coat it with a few coats of nail polish to see if this is your problem. If it runs, then replace it. The nail polish trick is a diagnostic tool. It is not a permanent fix.

You could also look at that area during cranking without the screwdriver. If it is arcing. If so, then, you know what to do. I have had bad rotors also, where the rotor internally shorted to the shaft. Not in a CRV, but another make.

I wanted to try the nail polish but was not able to, maybe next time. I did try to see if it was arcing while cranking but couldn't see anything. It was arcing on the backside and covered.


JPS Europa wrote:
Have you checked the supply voltage to the coil? Could be that with plugs in, voltage is getting pulled down below threshold voltage for spark due to extra load on starter which leads to next thought. Check to make sure you have solid ground to engine block. I fixed a problem on a neighbors car that acted almost exactly like this and the ground strap was corroded on one end.
Happy hunting!

Thanks for the suggestion. I wanted to check the ground before putting the new coil in just in case, my dad installed the new coil before I could get back to the car. No obvious change when extra ground strap is added now.

horchoha wrote:
I vote for faulty coil also. Too bad coil is in distributor. When I suspected my bad coil on Chev truck I waited until dark, cranked engine to start and watched the spark jump across/around coil body instead of though HT wire.

I did look at it while cranking but unfortunately the arcing was on the backside so I didn't see it anyways.

Pictures...


Attachments:
burnt coil 1.png
burnt coil 1.png [ 1.4 MiB | Viewed 3686 times ]
burnt coil 2.png
burnt coil 2.png [ 1.65 MiB | Viewed 3686 times ]

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PostPosted: March 2, 2020, 11:17 am 
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congrats! :D

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PostPosted: March 2, 2020, 11:46 am 
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Location: Holden, Alberta, Canada
Good job! :cheers:

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Perry's Locost Super Che7enette Build
Perry's TBird Based 5.0L Super 7 L.S.O.
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PostPosted: March 2, 2020, 12:56 pm 
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Location: West Chicago,IL
Good News! :cheers:

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