Please confirm these ignition coil readings
03-18-2018, 08:43 PM
#1
Drifting
Thread Starter
Please confirm these ignition coil readings
Troubleshooting a no-start condition after a 3.5 month clutch job, I have performed virtually the entire DME Test Plan (minus oscilloscope) and DME harness test points (thanks to John_AZ for that image). See my other thread "DME destroyed?"
Two ignition coil tests I performed have me puzzled. Clip 1 shows resistance across the two screws, and it's a negative value (?); clip 3 shows the test at the DME plug and I don't know what "Pulse voltage signal" is supposed to look like.
Can someone watch the brief clips and confirm that the results are proper?
Clip #1 - checking ignition coil resistance across the two screw connections:
Clip #2 - checking ignition coil resistance across the small green-wired screw and the centre tap to distributer, using the wire:
Clip #3 - checking ignition coil at DME plug, pin 1 & ground; specification is "Pulse voltage signal" -- I am unsure what that means
Is the coil testing showing a good coil?
Thanks,
Dan
PS: For reference purposes, here are videos of the speed & reference sensor testing:
Speed sensor:
Reference sensor:
Two ignition coil tests I performed have me puzzled. Clip 1 shows resistance across the two screws, and it's a negative value (?); clip 3 shows the test at the DME plug and I don't know what "Pulse voltage signal" is supposed to look like.
Can someone watch the brief clips and confirm that the results are proper?
Clip #1 - checking ignition coil resistance across the two screw connections:
Clip #2 - checking ignition coil resistance across the small green-wired screw and the centre tap to distributer, using the wire:
Clip #3 - checking ignition coil at DME plug, pin 1 & ground; specification is "Pulse voltage signal" -- I am unsure what that means
Is the coil testing showing a good coil?
Thanks,
Dan
PS: For reference purposes, here are videos of the speed & reference sensor testing:
Speed sensor:
Reference sensor:
Last edited by Dan Martinic; 03-18-2018 at 08:58 PM.
03-18-2018, 10:59 PM
#2
Nordschleife Master
When you take resistance measurement first zero the gauge or connect the leads together and deduct that amount from the readings, I don’t know if you did that. Also that is not a negative reading, it’s a void in that the guage cannot pick up a reading as you might not have it connected properly or you have it set on the wrong range.
Next, I’m not seeing if you disconnected the wires from the terminals on the coil, if you are testing the coil you must do that or the readings won’t mean anything. Coil primary readings (between the two terminals) should be low, in the range of 1 to 2 ohms. Also when you are measuring the secondary coil you must go between one of the coil terminals (any one) to the center coil terminal on the coil and not to the end of the ignition wire, otherwise you are also measuring the resistance of the ignition wire. A coil secondary reading should be high, in the 10k ohm range.
To measure pulse voltage accurately you need an oscilloscope, no way around that, although you can see from your readings that you do have a pulse so I’m guessing that means you are getting tach bounce.
Hope that helps.
Next, I’m not seeing if you disconnected the wires from the terminals on the coil, if you are testing the coil you must do that or the readings won’t mean anything. Coil primary readings (between the two terminals) should be low, in the range of 1 to 2 ohms. Also when you are measuring the secondary coil you must go between one of the coil terminals (any one) to the center coil terminal on the coil and not to the end of the ignition wire, otherwise you are also measuring the resistance of the ignition wire. A coil secondary reading should be high, in the 10k ohm range.
To measure pulse voltage accurately you need an oscilloscope, no way around that, although you can see from your readings that you do have a pulse so I’m guessing that means you are getting tach bounce.
Hope that helps.
03-19-2018, 06:31 AM
#3
Drifting
Thread Starter
Thank you. Very helpful!
I did not zero the gauge or disconnect the coil wires. Will try that.
I have no tach movement whatsoever. No bounce, twitch, tremor... nothing.
There is a 99% possibility that, during a heater valve removal, I turned the key to ON while a ground was disconnected from the bellhousing
I did not zero the gauge or disconnect the coil wires. Will try that.
I have no tach movement whatsoever. No bounce, twitch, tremor... nothing.
There is a 99% possibility that, during a heater valve removal, I turned the key to ON while a ground was disconnected from the bellhousing
03-19-2018, 01:56 PM
#4
Nordschleife Master
Thank you. Very helpful!
I did not zero the gauge or disconnect the coil wires. Will try that.
I have no tach movement whatsoever. No bounce, twitch, tremor... nothing.
There is a 99% possibility that, during a heater valve removal, I turned the key to ON while a ground was disconnected from the bellhousing
I did not zero the gauge or disconnect the coil wires. Will try that.
I have no tach movement whatsoever. No bounce, twitch, tremor... nothing.
There is a 99% possibility that, during a heater valve removal, I turned the key to ON while a ground was disconnected from the bellhousing
03-19-2018, 08:04 PM
#5
Drifting
Thread Starter
Today, I called ecu doctors.. very helpful.. good reputation. However, the gentleman was surprised a lack of ground could damage the dme, suggesting they've never seen that. His tech also agreed likely not an issue. I did highlight that the factory lit suggests immediate destruction.
Anyway, I've taken readings from both the sensors' end and the dme harness pins; no difference, all good.
I think I have to send the DME down to Florida. Ah, well.
Anyway, I've taken readings from both the sensors' end and the dme harness pins; no difference, all good.
I think I have to send the DME down to Florida. Ah, well.
03-20-2018, 02:36 AM
#6
Drifting
In the future disconnect the battery before working with electrical stuff on every vehicle you work on. It's just good business to do so. Also take off any jewelry before working on any vehicle. Safety first. I have seen some seriously nasty photo's of body parts that couldn't be identified anymore due to jewelry. Jewelry and electricity creat something special when they meet.
03-20-2018, 07:11 AM
#7
Drifting
Thread Starter
Would you believe that I always do, and when I began this big clutch job, I did just that? But then.... as I was draining coolant for the added heater valve removal.... to "move" the heater control to full warm, I re-connected the battery and turned the key to ON.
AND I had a sinking feeling as I was doing that... like "this doesn't feel right". My body knew what my dumb mind and lack of experience didn't.
There are two ways to learn something: easy way... hard way. But, at least it's learning
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06-01-2019, 05:30 PM
#9
Drifting
Thread Starter
It was a month's worth of diagnosis.. oscilloscope madness... and one helpful lead that took me to a thread where a fine gentleman spent a year--yes, one year--only to discover that one of his brand new FAE sensors had a fatal flaw. Turns out I had the exact same issue with one of my new FAE sensors. The solution was to buy and install new Bosch sensors.
I'd point you to the entire thread but it's very time consuming to read and I'll save you the labour.
Have you installed new sensors and are they FAE brand?
06-01-2019, 09:19 PM
#10
Three Wheelin'
My sensors say "Made in Germany" on the side. So I believe they are Bosch. I saw your thread/video and Tom's video about the FAE sensor with continuity. I tested one of them and didn't get continuity. Maybe I'll pull the other one just to verify as well.
06-02-2019, 12:41 PM
#11
Drifting
Thread Starter
Most likely, they don't suffer from the FAE issue.
You don't say if they are new sensors. Did the no tach bounce suddenly appear or was it after some work in the area?
It is very common for the wiring connectors to be corroded or no longer making good contact. This is a hidden issue under the boot ends on the connectors (original engine wiring ends). Replacement wires and connectors are available. I got a new pair from one of the aftermarket places. Ironically, I haven't installed them yet.
A quick test is have someone wiggle the cnnections while you watch for tach bounce.
If for you feel the connections are good, next you can test at the DME. Short of an oscilloscope, a little 12v LED could show if there's any signal, but I like Tom's new testing gadget.
If you get some signal from the sensors at the DME end and they are Bosch sensors, you may have a problem inside the DME itself. If you suspect that, open it up and resolder any joints that have tiny hair-like lines on them. I did that once and it fixed a random stalling issue
You don't say if they are new sensors. Did the no tach bounce suddenly appear or was it after some work in the area?
It is very common for the wiring connectors to be corroded or no longer making good contact. This is a hidden issue under the boot ends on the connectors (original engine wiring ends). Replacement wires and connectors are available. I got a new pair from one of the aftermarket places. Ironically, I haven't installed them yet.
A quick test is have someone wiggle the cnnections while you watch for tach bounce.
If for you feel the connections are good, next you can test at the DME. Short of an oscilloscope, a little 12v LED could show if there's any signal, but I like Tom's new testing gadget.
If you get some signal from the sensors at the DME end and they are Bosch sensors, you may have a problem inside the DME itself. If you suspect that, open it up and resolder any joints that have tiny hair-like lines on them. I did that once and it fixed a random stalling issue
06-02-2019, 10:11 PM
#12
Three Wheelin'
Most likely, they don't suffer from the FAE issue.
You don't say if they are new sensors. Did the no tach bounce suddenly appear or was it after some work in the area?
It is very common for the wiring connectors to be corroded or no longer making good contact. This is a hidden issue under the boot ends on the connectors (original engine wiring ends). Replacement wires and connectors are available. I got a new pair from one of the aftermarket places. Ironically, I haven't installed them yet.
A quick test is have someone wiggle the cnnections while you watch for tach bounce.
If for you feel the connections are good, next you can test at the DME. Short of an oscilloscope, a little 12v LED could show if there's any signal, but I like Tom's new testing gadget.
If you get some signal from the sensors at the DME end and they are Bosch sensors, you may have a problem inside the DME itself. If you suspect that, open it up and resolder any joints that have tiny hair-like lines on them. I did that once and it fixed a random stalling issue
You don't say if they are new sensors. Did the no tach bounce suddenly appear or was it after some work in the area?
It is very common for the wiring connectors to be corroded or no longer making good contact. This is a hidden issue under the boot ends on the connectors (original engine wiring ends). Replacement wires and connectors are available. I got a new pair from one of the aftermarket places. Ironically, I haven't installed them yet.
A quick test is have someone wiggle the cnnections while you watch for tach bounce.
If for you feel the connections are good, next you can test at the DME. Short of an oscilloscope, a little 12v LED could show if there's any signal, but I like Tom's new testing gadget.
If you get some signal from the sensors at the DME end and they are Bosch sensors, you may have a problem inside the DME itself. If you suspect that, open it up and resolder any joints that have tiny hair-like lines on them. I did that once and it fixed a random stalling issue
06-03-2019, 12:09 PM
#13
Drifting
Thread Starter
I have no idea how this VEMS stuff works, but something is either wrong there or with your DME or KLR (or wiring for either). That's my guess. Good luck!