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I've been watching youtube like mad... lots of non-auto application.. and the auto ones seem focused on the screen as opposed to connection and settings.
I kinda get the concept now but just couldn't figure baseline settings for V and time div. That, and there's a lot of other things to be set on this beast of a scope... Last night I tried and tried but couldn't get anything useful to show... so I gave up and today left the DME with a local mechanic who might know a tech that can look at it.
If I can't get it fixed locally, it's off to Florida. This clutch job is one for the record books.
I did go ahead and order the simpler recommended dso138 for <30$; should be here in 18 weeks or so lol!
Spring has arrived... beautiful sunny days all week..... Oh how it sits in all it's fully-assembled glory....... man, this hurts!
I suspect you are down a rabbit hole that may or may not be helpful with the o-scope, etc. With the car fully assembled, I'd go back to the basics. Crank the engine and check for spark on the #1 spark plug lead, by pulling it off the plug, and seeing it you have spark. You'll need to put a thick solid wire or other conductor into the boot to make contact with lead's connector, and place the other end maybe 2mm away from a grounded engine part like the intake manifold. Don't touch it while cranking the motor or you could get zapped. Watch for a spark as someone cranks the motor for you. Chances are you won't have spark if you're not seeing a tach bounce, but worth checking. If you don't have spark, then I'd check to see if the injectors are firing when you crank the motor. Noid lights are available, but it's more reliable to pull a spark plug, crank the motor a good amount, then look/smell for fuel in the cylinder. If it's getting fuel, you'll know it. Once you know if you're problem is no spark, no fuel, both, or neither, it will help send you (us) down the right diagnostic path. You may end up back at the DME, but there are lots of other things that could go wrong first, especially if you didn't actually run the motor with the ground strap off. Running the motor will increase the amps/current running through the DME (via the ignition and injection drivers) which increases the chance you fried some component not intended to ground that much current. If you simply powered on the DME without running the motor, you've got a better chance I'd say.
Thanks Tom. I did pull a plug out, lean it against the manifold, and cranked while a buddy watched and saw nothing. I also put a plug into the wire from the coil and did the same (not sure it this is correct procedure, but nonetheless).
There's plenty of fuel; I can see it in the spark plug hole. All the tests at the DME harness pins appear fine (voltages, resistances).
The one that confirms it for me is the DME test #14 (see initial post). There appears to be zero signal from the DME to the KLR on the KLR's harness ignition pin #9.
Though you're supposed to use a 'scope, I assume that a voltmeter would register something--just like it does for ref & speed sensors.
Currently, I'm waiting to hear back from a potential local tech who now has the unit. In the meantime, I might play with the 'scope just to see if I can learn how to get the right signals showing. I'll play on the ref & speed sensors. Learning how to use the scope seems like a good thing; especially since I ordered that cheap one from China
One thing did perplex me though: the tach / upshift light test failed (no continuity between pins 11 & 21). I figure that's because my upshift light doesn't work (or doesn't exist? I don't recall Turbos having one?)
Tach worked fine before shut down in December. However.....................................
I have located a local used DME but it's for early Turbo. It's a bit of drive to get... and a bit of money to buy.
Mine is a 1988, built in Aug 1987 (well, that's what is stamped on the original clutch disk I pulled out), and has the DME ending in "08". 28 PIN.
I don't mind running an older DME if all else being equal. I understand it's easy to convert to 28 PIN if necessary. But.. there must have been other changes with all these revision numbers of DME, no? The '86s start with "02". There's lots of changes to the cars themselves
Thanks Tom. I did pull a plug out, lean it against the manifold, and cranked while a buddy watched and saw nothing. I also put a plug into the wire from the coil and did the same (not sure it this is correct procedure, but nonetheless).
There's plenty of fuel; I can see it in the spark plug hole. All the tests at the DME harness pins appear fine (voltages, resistances).
The one that confirms it for me is the DME test #14 (see initial post). There appears to be zero signal from the DME to the KLR on the KLR's harness ignition pin #9.
Though you're supposed to use a 'scope, I assume that a voltmeter would register something--just like it does for ref & speed sensors.
Currently, I'm waiting to hear back from a potential local tech who now has the unit. In the meantime, I might play with the 'scope just to see if I can learn how to get the right signals showing. I'll play on the ref & speed sensors. Learning how to use the scope seems like a good thing; especially since I ordered that cheap one from China
One thing did perplex me though: the tach / upshift light test failed (no continuity between pins 11 & 21). I figure that's because my upshift light doesn't work (or doesn't exist? I don't recall Turbos having one?)
Tach worked fine before shut down in December. However.....................................
So sounds like you have fuel but no spark. That test #14 is checking for a very short, logic-level pulse from the DME, which will often not register as anything on a multimeter. However, if you don't have spark, chances are you don't have that pulse (though it's possible the issue is downstream of the DME). It's very possible your no-spark is due to a bad DME, but equally or even more likely it's something upstream of the DME like the speed/ref sensors or their wiring (or alarms/ignition switches, relays, etc.) or something downstream of the DME like the coil, cap, rotor, etc.
Every time I convince myself it's the DME, I get another glimmer of hope lol
Now I'm determined as ever to learn the oscilloscope! After I do, I will grab my DME from where I left it and check to see that signal from KLR pin 9.
I'll have to figure out what volt & time division to set the 'scope. What's a good starting point? 5V and 50ms? And, do I have to figure out that "trigger" thing?
Use an analog meter and rotate the engine. A digital meter isn't fast enough to display the readouts. You want to see the analog meter needle bounce. Also check your sensors to make sure they didn't hit the Allen screws in the flywheel and starter ring. You did gap them after you replaced the clutch I'm guessing? Otherwise you will be having this issue. Too close is bad and to far away is bad.
If you are getting fuel from the injectors, verify you are getting spark.
To check for spark, a simple LED (with resistor of course) or noid light between coil terminals will light up on/off if the DME is sending the ignition signal.
If no ignition signal, it's possible your KLR is the problem. Disconnect KLR and short (on the connector side - harness) pin #9 and #16. Repeat previous test and see if LED flickers.
If it does, then KLR may be the issue, or the KLR chip (I have seen them go bad).
If you are getting fuel (Injectors firing), a very good chance the plugs flooded and need replacing.
While testing all the ignition stuff, it's best to remove the fuse for fuel pump.
If you are getting fuel from the injectors, verify you are getting spark.
To check for spark, a simple LED (with resistor of course) or noid light between coil terminals will light up on/off if the DME is sending the ignition signal.
If no ignition signal, it's possible your KLR is the problem. Disconnect KLR and short (on the connector side - harness) pin #9 and #16. Repeat previous test and see if LED flickers.
If it does, then KLR may be the issue, or the KLR chip (I have seen them go bad).
If you are getting fuel (Injectors firing), a very good chance the plugs flooded and need replacing.
While testing all the ignition stuff, it's best to remove the fuse for fuel pump.
Hopefully, I can check with a borrowed DME first... then if still no spark, I'll try the shorting. Also try the oscilloscope on that pin (I'm determined to learn that tool!)
To check for spark, a simple LED (with resistor of course) or noid light between coil terminals will light up on/off if the DME is sending the ignition signal.
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Which terminals? The outside screw terminals or one screw + the centre? And I think I know but... why the resistor? What value & how to wire the resistor? I have a 12 volt LED that's why I'm asking..
Which terminals? The outside screw terminals or one screw + the centre? And I think I know but... why the resistor? What value & how to wire the resistor? I have a 12 volt LED that's why I'm asking..
Wire terminals at coil where the black and the green wires are connected. (not center of coil).
The resistor is to protect (limit the current to) the LED. You cannot use a bare LED. Each LED is rated to how much current it can handle, the resistor value is calculated based on the LED specs.
Google " protect LED with resistors " lots of info.
If you have a LED setup you can use with 12V (not just a bare LED), then no need for resistor, it probably has one already.
Basically you want an LED circuit to handle 12V. It'll flicker if the coil is getting firing triggers from DME.
Thanks. I have a bare LED rated for 12V; it's just a little LED in a tiny plastic holder with two wires sticking out. Maybe there's a resistor in it.. or maybe the actual LED is just rated for 12V. Not sure. Got it from electronics surplus.
I did solder on some round connectors to those wires--the same that fit into that diagnostic plug behind the driver's side shock tower. I tried to use it when setting idle to confirm ICV is out of the picture; but, I couldn't get it to light at the appropriate time. It lights fine across 12V & ground though.
I will do some reading on the whole LED thing for sure. Seems there is a lot of uses for diagnostic around our ignition systems
03-20-2018, 09:57 PM
