does this spark look good
02-08-2017, 03:52 PM
#4
im thinking its easier for the spark to travel through the boot and ground out there then travel through 15 feet of jumper cable to the negative terminal. Those are brand new spark wires.
02-08-2017, 04:47 PM
#5
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Sorry to repeat myself, but I had a brand new set of wire -- same brand -- that would arc from the boots from the first minute they were installed. Car ran terribly until I swapped them out. The boot should not arc like that, assuming it's real and not a video illusion. The jumper cable is supplying at least as good a ground path as the block would....(assuming the other end is well grounded). That said, if the issue pre-dated these wires, then it would have to be a weird (less likely) coincidence that both sets were bad...but certainly possible.
02-08-2017, 06:04 PM
#6
Sorry to repeat myself, but I had a brand new set of wire -- same brand -- that would arc from the boots from the first minute they were installed. Car ran terribly until I swapped them out. The boot should not arc like that, assuming it's real and not a video illusion. The jumper cable is supplying at least as good a ground path as the block would....(assuming the other end is well grounded). That said, if the issue pre-dated these wires, then it would have to be a weird (less likely) coincidence that both sets were bad...but certainly possible.
02-08-2017, 08:11 PM
#7
It is pointless to even answer that question. You cannot determine or even evaluate the strength of your ignition by looking at the spark at the plug, out of the engine while the system is under 0 (atmo) pressure.
Absolutely meaningless.
Absolutely meaningless.
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02-09-2017, 02:01 AM
#8
Ahh thank you ill just crank up the atmospheric pressure in my garage and repost video.
02-09-2017, 03:30 AM
#10
ok i appreciate your advice and am aware that pressure and conditions inside the cylinder affect spark conditions, however someone could still give an opinion based on the video if the spark looks weak or if they are concerned about the arcing coming out of the plug boots, i recieved some very good advice and thank you for yours as well I well take that into consideration.
02-09-2017, 01:25 PM
#11
ok i appreciate your advice and am aware that pressure and conditions inside the cylinder affect spark conditions, however someone could still give an opinion based on the video if the spark looks weak or if they are concerned about the arcing coming out of the plug boots, i recieved some very good advice and thank you for yours as well I well take that into consideration.
Remember the arcing from cracks in wires and boots will only get worse when the spark is under cylinder pressure.
It will always take the path (to ground) of least resistance.
02-10-2017, 10:48 AM
#12
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It's pretty hard for a DIY (or professional shop like me) to test 30-50,000V any other way.
02-10-2017, 02:27 PM
#13
[QUOTE=Perry 951;13948935]I disagree. Aside from checking resistance specs, this is a good way to analyze health of a coil. The color and thickness of the spark can be judged just fine this way. A weak coil will have a noticeably greenish blue and thin spark with little snap sound, whereas a good strong coil will have a white and relatively thick spark and a clear snap.
It's pretty hard for a DIY (or professional shop like me) to test 30-50,000V any other way.[/QUOTE
For a pro shop to test a coil this way is like asking the weather man to predict the weather by holding his finger in the air.
A 944 has an inductive Ignition system. So the coil plays a huge part in the energy released into the cylinder.
The coil of choice will have spec's that can be researched probably on the wed. Then the coil can be tested in place (engine running) with a simple scope.
The dwell time, rise time and saturation level of the coil can be measured on the scope. These values can them be compared against a good known coil.
The DIY that suspects the coil to be bad can go to any pro shop with test equipment and these tests can be done.
It's pretty hard for a DIY (or professional shop like me) to test 30-50,000V any other way.[/QUOTE
For a pro shop to test a coil this way is like asking the weather man to predict the weather by holding his finger in the air.
A 944 has an inductive Ignition system. So the coil plays a huge part in the energy released into the cylinder.
The coil of choice will have spec's that can be researched probably on the wed. Then the coil can be tested in place (engine running) with a simple scope.
The dwell time, rise time and saturation level of the coil can be measured on the scope. These values can them be compared against a good known coil.
The DIY that suspects the coil to be bad can go to any pro shop with test equipment and these tests can be done.
02-13-2017, 11:16 AM
#14
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Let's bring this conversation back to reality.
We're talking about a very common Bosch coil here; not a massively rare or expensive unit. The current production number is 0221118322 and costs about $80. For most shops, you're gonna pay an hour of diagnostic time for them to hook up a scope and check dwell and rise. Unless they are below $80 a hour, it's worthless to do so and a better value just to replace it. I also checked the Bosch site as well as my factory 951 manuals, Alldata, Identifix, and Motor and none of them list anything beyond primary and secondary resistance.
Without the charge time data, testing with a scope is about as accurate as viewing and listening to the spark. Comparing to another coil that you do not have specifications for is comparing nothing to nothing. Maybe you can contribute more to the community by supplying the information?
I've checked, looked at, and listened to hundreds of coils over the last 13 years of working on cars for a living, and probably even more in my 35 years of working on cars. You can tell a weak coil from a good one by the color, brightness, and sound of the spark.
We're talking about a very common Bosch coil here; not a massively rare or expensive unit. The current production number is 0221118322 and costs about $80. For most shops, you're gonna pay an hour of diagnostic time for them to hook up a scope and check dwell and rise. Unless they are below $80 a hour, it's worthless to do so and a better value just to replace it. I also checked the Bosch site as well as my factory 951 manuals, Alldata, Identifix, and Motor and none of them list anything beyond primary and secondary resistance.
Without the charge time data, testing with a scope is about as accurate as viewing and listening to the spark. Comparing to another coil that you do not have specifications for is comparing nothing to nothing. Maybe you can contribute more to the community by supplying the information?
I've checked, looked at, and listened to hundreds of coils over the last 13 years of working on cars for a living, and probably even more in my 35 years of working on cars. You can tell a weak coil from a good one by the color, brightness, and sound of the spark.