DIY Check for Spark
03-26-2013
#1
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DIY Check for Spark
Thanks RonJ
A very common cause for no-start engine problems is weak or no spark at the spark plugs. I created this thread to describe a relatively simple yet effective method to...
Check spark
Outcomes and troubleshooting
A) Some or all plugs have no spark or weak orange, yellow, or blue spark
Check the plug wires, distributor cap, and rotor. See FAQs sticky for diagrams of component parts.
B) All plugs have weak orange, yellow, or blue spark
Check whether the coil in the distributor is bad. The service manual or FAQs sticky has a diagram that describes resistance measurements to test the coil. Here are some tips for doing the coil test:
------------------------------------------------------------
A bad ICM can also sometimes cause weak spark. AutoZone tests ICMs for free. Also, here's an ICM testing DIY:
http://www.team-integra.net/forum/bl...eshooting.html
C) All plugs lack spark
Do these steps in order:
a) Check whether the timing belt snapped or stripped. This is most easily done by removing the oil filler cap and, while a buddy cranks the engine, by peering into the hole with a flashlight to look for evidence that the camshaft is turning (e.g., movement of the rocker arms). If the belt snapped (=no rocker arm movement), install a new timing belt, tension it properly, and then compression test the cylinders. The latter step is essential as major engine damage may have occurred when the timing belt snapped/stripped.
b) Check whether the important G101 ground wire on the thermostat housing (see FAQs sticky) is loose or corroded. If so, clean it thoroughly with steel wool and tighten. By the way, if G101 is disconnected or loose, the engine will lack both spark and fuel.
c) Check whether the CEL remains ON when the key is turned to ON(II). If so, pull the code(s) (see Codes sticky). If a code for one of the distributor sensors (codes 4, 8, or 9) or the igniter/ICM (code 15) is retrieved, then the distributor subassembly or igniter/ICM, respectively, is possibly bad. Further troubleshooting here would be:
e) Check whether the coil or igniter/ICM in the distributor is bad. Again, there are resistance tests for the coil (see FAQs sticky and above), but take the igniter/ICM to AutoZone for testing.
f) In some cases, lack of spark is due to a bad ECU. This is usually only considered if all tests described above yield negative results.
A very common cause for no-start engine problems is weak or no spark at the spark plugs. I created this thread to describe a relatively simple yet effective method to...
Check spark
1) Unplug all four fuel injector clips to avoid flooding the cylinders with gas during the procedure. (Thanks goes to Sonia's Driver for this tip.)
2) Buy a spare NGK spark plug for your engine (inexpensive $2-3) and gap it properly.
3) Remove the plug wire from one spark plug and insert the spare plug into the end.
4) While firmly grounding the threads of the spark plug against a clean metallic area of the valve cover, have a buddy crank the engine. If you are concerned about getting shocked, you can wear a rubber glove on the hand holding the spark plug, though this is really unnecessary if you take care to keep fingers or other body parts away from the spark plug tip.
5) With the engine cranking, you should see bright white spark (with only a faint bluish tinge) rather than weak orange, yellow, or blue spark at the tip of the plug.
6) Repeat procedure above for the remaining three spark plugs.
------------------------------------------------------------------------------------------------------------------------------2) Buy a spare NGK spark plug for your engine (inexpensive $2-3) and gap it properly.
3) Remove the plug wire from one spark plug and insert the spare plug into the end.
4) While firmly grounding the threads of the spark plug against a clean metallic area of the valve cover, have a buddy crank the engine. If you are concerned about getting shocked, you can wear a rubber glove on the hand holding the spark plug, though this is really unnecessary if you take care to keep fingers or other body parts away from the spark plug tip.
5) With the engine cranking, you should see bright white spark (with only a faint bluish tinge) rather than weak orange, yellow, or blue spark at the tip of the plug.
6) Repeat procedure above for the remaining three spark plugs.
Outcomes and troubleshooting
A) Some or all plugs have no spark or weak orange, yellow, or blue spark
Check the plug wires, distributor cap, and rotor. See FAQs sticky for diagrams of component parts.
B) All plugs have weak orange, yellow, or blue spark
Check whether the coil in the distributor is bad. The service manual or FAQs sticky has a diagram that describes resistance measurements to test the coil. Here are some tips for doing the coil test:
------------------------------------------------------------
Resistance testing the coil
Remove coil from the distributor for tests. Make measurements inside a room at about 70F. Note that Ohm scale recommendations below are irrelevant if you are using an digital multimeter that auto-ranges.
Primary coil resistance
The spec reading for the primary coil reading is very low resistance, so you need to use the lowest Ohm scale (e.g., 20 Ohms) for testing.
Steps:
1) Set multimeter to the lowest Ohm scale.
2) Touch the two meter probes together and note the reading. This reading represents the internal resistance of your multimeter.
3) Measure the primary coil resistance and note it.
4) Subtract the meter internal resistance reading from the primary coil resistance reading to obtain the actual primary coil resistance.
Secondary coil resistance
This is much easier.
Steps:
1) Set multimeter to the 20K (20,000) Ohm scale.
2) Measure the secondary coil resistance.
3) Done
------------------------------------------------------------Remove coil from the distributor for tests. Make measurements inside a room at about 70F. Note that Ohm scale recommendations below are irrelevant if you are using an digital multimeter that auto-ranges.
Primary coil resistance
The spec reading for the primary coil reading is very low resistance, so you need to use the lowest Ohm scale (e.g., 20 Ohms) for testing.
Steps:
1) Set multimeter to the lowest Ohm scale.
2) Touch the two meter probes together and note the reading. This reading represents the internal resistance of your multimeter.
3) Measure the primary coil resistance and note it.
4) Subtract the meter internal resistance reading from the primary coil resistance reading to obtain the actual primary coil resistance.
Secondary coil resistance
This is much easier.
Steps:
1) Set multimeter to the 20K (20,000) Ohm scale.
2) Measure the secondary coil resistance.
3) Done
A bad ICM can also sometimes cause weak spark. AutoZone tests ICMs for free. Also, here's an ICM testing DIY:
http://www.team-integra.net/forum/bl...eshooting.html
C) All plugs lack spark
Do these steps in order:
a) Check whether the timing belt snapped or stripped. This is most easily done by removing the oil filler cap and, while a buddy cranks the engine, by peering into the hole with a flashlight to look for evidence that the camshaft is turning (e.g., movement of the rocker arms). If the belt snapped (=no rocker arm movement), install a new timing belt, tension it properly, and then compression test the cylinders. The latter step is essential as major engine damage may have occurred when the timing belt snapped/stripped.
b) Check whether the important G101 ground wire on the thermostat housing (see FAQs sticky) is loose or corroded. If so, clean it thoroughly with steel wool and tighten. By the way, if G101 is disconnected or loose, the engine will lack both spark and fuel.
c) Check whether the CEL remains ON when the key is turned to ON(II). If so, pull the code(s) (see Codes sticky). If a code for one of the distributor sensors (codes 4, 8, or 9) or the igniter/ICM (code 15) is retrieved, then the distributor subassembly or igniter/ICM, respectively, is possibly bad. Further troubleshooting here would be:
--->(for sensor codes) measure the resistance of the sensors (spec = 350-700 Ohms) and their corresponding wires for a short or open.
--->( for code 15) (i) have AutoZone test the igniter/ICM, (ii) test the Blk/Yel wire attached to the coil and igniter/ICM for battery voltage with the key in ON(II), and (iii) test the Yel/Grn wire running between the igniter/ICM and the ECU for a short or open.
d) Check whether battery voltage is reaching the coil and igniter on the Blk/Yel wire in the distributor when the key is turned to ON(II). If not, there may be a bad wire from the ignition switch (or for 98-00 Civics, a blown fuse 9 in the under-hood fuse/relay box). A bad ignition switch is another possibility but, in this case, the engine will lack both spark and fuel.--->( for code 15) (i) have AutoZone test the igniter/ICM, (ii) test the Blk/Yel wire attached to the coil and igniter/ICM for battery voltage with the key in ON(II), and (iii) test the Yel/Grn wire running between the igniter/ICM and the ECU for a short or open.
e) Check whether the coil or igniter/ICM in the distributor is bad. Again, there are resistance tests for the coil (see FAQs sticky and above), but take the igniter/ICM to AutoZone for testing.
f) In some cases, lack of spark is due to a bad ECU. This is usually only considered if all tests described above yield negative results.
03-26-2013
#2
If you think a good mechanic is expensive, try hiring a bad one
Re: DIY Check for Spark
The only problem with using a spark plug for this test is that it is not a real stress test on the coil and the rest of the secondary ignition components.
It only takes about 4kV to ionize (jump) a 1.1mm free air gap (typical spark plug gap), but 4kV is not enough to run the engine under all conditions.
An ignition system needs to be capable of delivering at least 20kV+ to the spark plugs in order to run the engine properly.
That's about a 10mm free air gap at an absolute minimum (20kV) when checked at the spark plug, and I like to see the spark able to jump a gap of about 1/2 inch --or larger-- when checking directly at the coil itself. A new coil will deliver that much spark easily.
HTH
It only takes about 4kV to ionize (jump) a 1.1mm free air gap (typical spark plug gap), but 4kV is not enough to run the engine under all conditions.
An ignition system needs to be capable of delivering at least 20kV+ to the spark plugs in order to run the engine properly.
That's about a 10mm free air gap at an absolute minimum (20kV) when checked at the spark plug, and I like to see the spark able to jump a gap of about 1/2 inch --or larger-- when checking directly at the coil itself. A new coil will deliver that much spark easily.
HTH
Last edited by ezone; 09-13-2017 at 11:35 PM.
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