Oh, no... bizzarre electrical issue!
09-11-09, 12:46 AM
#1
Oh, no... bizzarre electrical issue!
So, here I am, two weeks from Sevenstock, just got all my beautification done... and I've got a strange electrical issue that just HAD to rear it's head 
Situation: Stock 80 GS with full emissions and rats nest, all of which has been fully functional.
Over the course of the last week, I:
1)pulled the dizzy to clean/lube/polish it and paint the external bits
2)changed out my Type 1 RacingBeat Gauge Adapter Block on the filter pedestal for a Type 2 block (just an aesthetic change, really)
3)installed fog lights, which are relay-fed (primary straight from the battery, relay is triggered off the hazard lights fuse - works fine)
4)made a simple harness repair for the pigtail from the block temp sensor; insulation had hardened and split, so I solder-spliced a new pigtail on.
First restart tonight, and since I'd pulled the dizzy I knew I needed to re-time.
I pull out the choke, car started normally after about 3 seconds cranking, warms up, comes down off choke to idle. I set up my timing light.
Long story short, I have the following symptoms:
1) At idle, Trailing ignition is showing massive crosstalk from Leading; so much so that at first I thought I was on the wrong plug wire. Close observation shows that trailing signal is firing on correct timing about one pulse out of three (the timing mark goes yellow-yellow-red-yellow-red-yellow-yellow-etc... no pattern really.) 80's have been known to be prone to crosstalk because of the remote-ignitor design, but up til now I've never had a problem. I verified that the dizzy is wired correctly and the ignitor box ground is clean and tight.
2) At idle, my aftermarket electrical guages read normally. Anywhere above about 1500 RPM accelerating, the needles immediately peg below the zero lines. Grounding the sender shells with a jumper to the chassisprevents this symptom, which seems to maybe indicate an engine grounding fault, but one that is RPM dependent (WTF?).
What I've checked so far:
1)checked ground at strut tower (good) and metered ground from engine to chassis; zero measuable resistance while off.
2)Verified that the ignitor to dizzy cable is properly connected, the condenser at the dizzy is fine, and the black-with-white-strpe positive coil wire is good through to the condenser.
3)guage senders are fine, not shorted, and the oil pedestal base to strut-tower ground point shows zero ohms with engine off. Guage sender bodies to ground read zero ohms with engine off.
had to pack it in at that point for the night.
I need some suggestions as to where to look; this one's got me running in circles.
Any inspirations from our resident SA guys?
Situation: Stock 80 GS with full emissions and rats nest, all of which has been fully functional.
Over the course of the last week, I:
1)pulled the dizzy to clean/lube/polish it and paint the external bits
2)changed out my Type 1 RacingBeat Gauge Adapter Block on the filter pedestal for a Type 2 block (just an aesthetic change, really)
3)installed fog lights, which are relay-fed (primary straight from the battery, relay is triggered off the hazard lights fuse - works fine)
4)made a simple harness repair for the pigtail from the block temp sensor; insulation had hardened and split, so I solder-spliced a new pigtail on.
First restart tonight, and since I'd pulled the dizzy I knew I needed to re-time.
I pull out the choke, car started normally after about 3 seconds cranking, warms up, comes down off choke to idle. I set up my timing light.
Long story short, I have the following symptoms:
1) At idle, Trailing ignition is showing massive crosstalk from Leading; so much so that at first I thought I was on the wrong plug wire. Close observation shows that trailing signal is firing on correct timing about one pulse out of three (the timing mark goes yellow-yellow-red-yellow-red-yellow-yellow-etc... no pattern really.) 80's have been known to be prone to crosstalk because of the remote-ignitor design, but up til now I've never had a problem. I verified that the dizzy is wired correctly and the ignitor box ground is clean and tight.
2) At idle, my aftermarket electrical guages read normally. Anywhere above about 1500 RPM accelerating, the needles immediately peg below the zero lines. Grounding the sender shells with a jumper to the chassisprevents this symptom, which seems to maybe indicate an engine grounding fault, but one that is RPM dependent (WTF?).
(just came to me while writing that this symptom is maybe synchronized with the emissions signal that kills the trailing ignition on California 80's during accel...?)
3) Engine behavior decelerating is poor; multiple backfires from even light rpm down to idle. hasn't been an issue with this car before. Doesn't "feel" right, which I'm sure has to do with the trailing being out of whack. Acceleration seems smooth, though - no misfires etc. Idle is as smooth as usual.What I've checked so far:
1)checked ground at strut tower (good) and metered ground from engine to chassis; zero measuable resistance while off.
2)Verified that the ignitor to dizzy cable is properly connected, the condenser at the dizzy is fine, and the black-with-white-strpe positive coil wire is good through to the condenser.
3)guage senders are fine, not shorted, and the oil pedestal base to strut-tower ground point shows zero ohms with engine off. Guage sender bodies to ground read zero ohms with engine off.
had to pack it in at that point for the night.
I need some suggestions as to where to look; this one's got me running in circles.
Any inspirations from our resident SA guys?
09-11-09, 03:06 AM
#2
No - but a boatload of sympathy and kudos for heroic attempts at working it thru Glen
you mentioned the ignitor crosstalk (which I first read about on Racing Beat site) - do you have/would it be worth swapping in another ignitor (like they grow on trees...)?
Stu Aull
80 GS
Alaska
you mentioned the ignitor crosstalk (which I first read about on Racing Beat site) - do you have/would it be worth swapping in another ignitor (like they grow on trees...)?
Stu Aull
80 GS
Alaska
09-11-09, 07:14 AM
#3
I just so happen to have a pair of J-105s if ya need them. Those can be hard to come by as they are only on the '80 model.
Did you try moving the pickup on the plug wire? I know that even on FBs it is common to pickup the leading signal even when clipped on trailing. Sometimes moving the pickup closer to the dizzy cap helps. Might also be worth removing the ignitors and making sure all connection are clean including the screws which go through the ignitors (helps to ground them). Put some new heatsink compound on the back of the ignitors when reinstalling.
For you aftermarket senders, are they electric based (assume so)? Where are you getting power from? Did you use teflon tape or anything like that to seal the threads at the sender? Funky electrical problems that are RPM dependant can also be caused by an alternator that is on its way south or that has poor grounding (make sure that the ears of the alt and where is mounts to are clean). If all else fails, try to run a new ground between the block and the chassis.
Also, check fuses. It might be that your ECU is not getting juice or has a poor ground. This could be the cause of the backfires. Might be worth doing some testing at the ECU if all the fuses look okay. I figure that the decel behavior is either the signal side (ECU) or receiving side (solenoid unplugged, problem with one of the othe remission devices, etc.).
Did you try moving the pickup on the plug wire? I know that even on FBs it is common to pickup the leading signal even when clipped on trailing. Sometimes moving the pickup closer to the dizzy cap helps. Might also be worth removing the ignitors and making sure all connection are clean including the screws which go through the ignitors (helps to ground them). Put some new heatsink compound on the back of the ignitors when reinstalling.
For you aftermarket senders, are they electric based (assume so)? Where are you getting power from? Did you use teflon tape or anything like that to seal the threads at the sender? Funky electrical problems that are RPM dependant can also be caused by an alternator that is on its way south or that has poor grounding (make sure that the ears of the alt and where is mounts to are clean). If all else fails, try to run a new ground between the block and the chassis.
Also, check fuses. It might be that your ECU is not getting juice or has a poor ground. This could be the cause of the backfires. Might be worth doing some testing at the ECU if all the fuses look okay. I figure that the decel behavior is either the signal side (ECU) or receiving side (solenoid unplugged, problem with one of the othe remission devices, etc.).
09-11-09, 07:59 AM
#4
Waffles - hmmm good
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I would really focus on what you recently worked on if it was all
working flawlessly before. Like the dizzy, the pedestal block change,
the pigtail splice, etc. It had to be some thing to do with that work.
It could be when messing with the dizzy that you pulled on the
wires that go from the dizzy over to the ignitors and now either
internally or externally they are shorting causing the cross talk.
They follow a torturous path down along the block, under the AC,
to the strut tower and into the igniter box. Try wiggling those around
some and see with the timing light if the behavior changes.
Disconnect the fog lights to make sure thats not the issue.
You have two issues and multiple unknowns to debug here so focus
on either the timing issue or the guage issue and start eliminating/nullifying
things you changed recently until you get a change.
working flawlessly before. Like the dizzy, the pedestal block change,
the pigtail splice, etc. It had to be some thing to do with that work.
It could be when messing with the dizzy that you pulled on the
wires that go from the dizzy over to the ignitors and now either
internally or externally they are shorting causing the cross talk.
They follow a torturous path down along the block, under the AC,
to the strut tower and into the igniter box. Try wiggling those around
some and see with the timing light if the behavior changes.
Disconnect the fog lights to make sure thats not the issue.
You have two issues and multiple unknowns to debug here so focus
on either the timing issue or the guage issue and start eliminating/nullifying
things you changed recently until you get a change.
09-11-09, 10:30 AM
#6
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yeah if it was fine before chances are it was something you did
09-11-09, 10:54 AM
#7
Lives on the Forum
Wait a minute. So, in order to turn on your fog lights, you have to turn on the hazard flashers?
Check the engine ground near the starter, and the power cable as well.
Good luck...
.
Check the engine ground near the starter, and the power cable as well.
Good luck...
.
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09-11-09, 11:01 AM
#8
OK, bunch of good suggestions here. I think I have a primary and fallback plan mapped out:
Primary:
1) isolate out all new work (foglights, mainly, but disconnect gauges too; easy enough)
2) careful visual of all work areas, look for disturbed connections or possible rub-shorts.
3) reclean all grounds (incl. engine ground @ starter) & verify ignitor box wiring & ECU connector, fuse, and ground. Signals check of ECU if necessary (PITA to get to)
4) meter pickup coil wiring, look for possible pinches/shorts
5) verify ignitor grounds and heatsinking, swap in spare ignitors & spare ignitor box for test purposes if necessary. Last ditch, swap to old pickup coils and re-test, though they were pretty old when retired.
FALLBACK;
Upgrade to 81 dizzy. Fallback because it presents smog-test complications, and because I don't have parts at hand.
Answers to specific questions:
Yep; on the list of things to try, thanks!
I have a few known-good spare J-105's, thanks. I even have a known-good (but ugly) spare ignitor box, and my old pickup coil set which has iffy bearings but is otherwise workable. So I'm pretty well-fixed in the swap department, for testing.
Yep; no difference even with the pickup right at the cap.
This was last done about 9 months ago (only about 1000 road miles) when I was chasing that phantom miss. Easy enough to check again; on the list.
Yep, electrical gauges. I installed them several years back; I don't recall exactly where I tapped power from (blush) but it's a switched accessory lead, and hasn't previously been an issue. Fairly sure it's the same feed that runs the power for the stereo. The gauges have worked reliably for ages, so clearly something has changed.
The alt was tested good less than 1000 miles ago; I will recheck it's grounding and output, though. I have a shunt meter, so I can test actual amperage out.
I did use teflon tape (NPT threads, so you gotta seal somehow) but verified that the gauge bodies are grounded properly to the oil pedestal.
I'm going to test with a block ground lead tonight.
On the list, thanks.
Yep, either that or something that got pinched/stressed in the process, while working in the general area. On the list.
I was pretty careful, but definitely bears re-examination. I'm hoping I can feed the cable without having to undo the AC bracket again; it's a PITA. I seem to remember the connector won't fit thru, though. Frankly, the whole AC design on the SAs was a real hackjob by Mazda. Most of it is even fitted with SAE instead of metric hardware!
On the list.
Yeah, though I have a sneaking suspicion they will turn out to be related. The ignition issue (and the decel misbehavior) is the higher priority; the gauge prob I can work around by re-grounding, though that doesn't really explain anything & I hate leaving problems unanalyzed.
The one thing I don't have handy, sadly, is a newer dizzy and harness for same; I've been trying to keep the engine compartment as SA-complete as possible, and so have never bought one. I'm saving this one as a last-resort due to the need for parts, but it's a worthy idea.
No; Power is pulled from the fuse that feeds the hazard lights, AC clutch, and the power mirror circuit. Upstream from the hazard switch.
On the list, thanks.
Thanks for all the insights, guys. Keep 'em coming; I'm all over this problem as soon as I get home from work tonight!
Discussing it here really helps focus the mind.
Primary:
1) isolate out all new work (foglights, mainly, but disconnect gauges too; easy enough)
2) careful visual of all work areas, look for disturbed connections or possible rub-shorts.
3) reclean all grounds (incl. engine ground @ starter) & verify ignitor box wiring & ECU connector, fuse, and ground. Signals check of ECU if necessary (PITA to get to)
4) meter pickup coil wiring, look for possible pinches/shorts
5) verify ignitor grounds and heatsinking, swap in spare ignitors & spare ignitor box for test purposes if necessary. Last ditch, swap to old pickup coils and re-test, though they were pretty old when retired.
FALLBACK;
Upgrade to 81 dizzy. Fallback because it presents smog-test complications, and because I don't have parts at hand.
Answers to specific questions:
For you aftermarket senders, are they electric based (assume so)? Where are you getting power from? Did you use teflon tape or anything like that to seal the threads at the sender? Funky electrical problems that are RPM dependant can also be caused by an alternator that is on its way south or that has poor grounding (make sure that the ears of the alt and where is mounts to are clean). If all else fails, try to run a new ground between the block and the chassis.
The alt was tested good less than 1000 miles ago; I will recheck it's grounding and output, though. I have a shunt meter, so I can test actual amperage out.
I did use teflon tape (NPT threads, so you gotta seal somehow) but verified that the gauge bodies are grounded properly to the oil pedestal.
I'm going to test with a block ground lead tonight.
Also, check fuses. It might be that your ECU is not getting juice or has a poor ground. This could be the cause of the backfires. Might be worth doing some testing at the ECU if all the fuses look okay. I figure that the decel behavior is either the signal side (ECU) or receiving side (solenoid unplugged, problem with one of the othe remission devices, etc.).
It could be when messing with the dizzy that you pulled on the
wires that go from the dizzy over to the ignitors and now either
internally or externally they are shorting causing the cross talk.
They follow a torturous path down along the block, under the AC,
to the strut tower and into the igniter box. Try wiggling those around
some and see with the timing light if the behavior changes.
wires that go from the dizzy over to the ignitors and now either
internally or externally they are shorting causing the cross talk.
They follow a torturous path down along the block, under the AC,
to the strut tower and into the igniter box. Try wiggling those around
some and see with the timing light if the behavior changes.
On the list.
Thanks for all the insights, guys. Keep 'em coming; I'm all over this problem as soon as I get home from work tonight!
Discussing it here really helps focus the mind.
09-12-09, 01:20 AM
#13
OK, here's the results of tonight's efforts; I don't have it solved, but I think I have it cornered.
First, there are two separate and distinct issues, and they don't appear to have anything to do with one another. They also appear to have nothing to do with any of my recent additions, as I isolated out all the new wiring and no change was seen.
1) The guage fault: It's not a grounding problem in the traditional sense, and although it's related to engine RPMs, that's a byproduct: I believe it's actually related to oil pressure.
First, there are two separate and distinct issues, and they don't appear to have anything to do with one another. They also appear to have nothing to do with any of my recent additions, as I isolated out all the new wiring and no change was seen.
1) The guage fault: It's not a grounding problem in the traditional sense, and although it's related to engine RPMs, that's a byproduct: I believe it's actually related to oil pressure.
Careful observation showed the following:
a. All three guages (voltage, oil press, oil temp) draw power and instrument ground from the same connections - - but only the pres and temp guages are exhibiting the fault.
b. I disconnected the guages from the senders (I connectorized when I installed, so they have their own little harness); both guages went 'negative.'
c. Watching carefully, the two guages don't both go negative at exactly the same time, or at exactly the same RPM... and there's a critical RPM for each where they flutter. This rules out anything in the emissions system triggering the fault, because they all are debounced, they activate at higher RPMS than this problem is showing up at.
d. The only electrical that activates close to the same RPM is the idle switch on the carb, and it was fairly easy to check and find that it was normal.
e. no unusual ground voltages are seen when testing with a meter. A couple millivolts is all, which is normal enough on the engine ground for these cars.
f. Using a test clip lead to ground the sensor shell directly makes the problem go away... but produces no other symptoms.
My conclusion is that I'm losing ground to the sensors as oil pressure rises, which is probably pushing them back against the teflon tape. I'm going to pull the sensor adaptor, and replace the tape with a small amount of teflon paste instead (per Trochoid). I'm betting this will solve the problem, but if not, I'm just going to make a ground strap for the sensor adaptor.
2) The ignition issue (trailing firing on leading signal a lot)a. All three guages (voltage, oil press, oil temp) draw power and instrument ground from the same connections - - but only the pres and temp guages are exhibiting the fault.
b. I disconnected the guages from the senders (I connectorized when I installed, so they have their own little harness); both guages went 'negative.'
c. Watching carefully, the two guages don't both go negative at exactly the same time, or at exactly the same RPM... and there's a critical RPM for each where they flutter. This rules out anything in the emissions system triggering the fault, because they all are debounced, they activate at higher RPMS than this problem is showing up at.
d. The only electrical that activates close to the same RPM is the idle switch on the carb, and it was fairly easy to check and find that it was normal.
e. no unusual ground voltages are seen when testing with a meter. A couple millivolts is all, which is normal enough on the engine ground for these cars.
f. Using a test clip lead to ground the sensor shell directly makes the problem go away... but produces no other symptoms.
My conclusion is that I'm losing ground to the sensors as oil pressure rises, which is probably pushing them back against the teflon tape. I'm going to pull the sensor adaptor, and replace the tape with a small amount of teflon paste instead (per Trochoid). I'm betting this will solve the problem, but if not, I'm just going to make a ground strap for the sensor adaptor.
a. I checked all the pertinent grounds and connections very carefully, and all are clean, tight, and in the correct places.
b. I checked coil resistance on the pickups, and both were nominal and equal, and within only a couple ohms of my spare set. No shorts exist between any of the wires, nothing is open or intermittent even when wiggled violently, and waving a magnet at them produces a good strong response.
c. After checking & tightening the grounds and carefully spreading all leads, I started the car and immediately started looking at the timing with the light, even before the car had warmed up. At first, the problem seemed improved... but as the car warmed up, I started noticing the problem more and more. By the time it was fully warm and at idle, things looked much the same as yesterday.
This has me leaning toward either the trailing ignitor or the ignitor amp box. Tomorrow morning, I'm swapping in my known-good spare box with ignitors already on it.
I expect it will change the sumptoms. Which just means I have to pretty my spare up, or mess with swapping ignitors & boxes around.
More tomorrow; sleep now.
b. I checked coil resistance on the pickups, and both were nominal and equal, and within only a couple ohms of my spare set. No shorts exist between any of the wires, nothing is open or intermittent even when wiggled violently, and waving a magnet at them produces a good strong response.
c. After checking & tightening the grounds and carefully spreading all leads, I started the car and immediately started looking at the timing with the light, even before the car had warmed up. At first, the problem seemed improved... but as the car warmed up, I started noticing the problem more and more. By the time it was fully warm and at idle, things looked much the same as yesterday.
This has me leaning toward either the trailing ignitor or the ignitor amp box. Tomorrow morning, I'm swapping in my known-good spare box with ignitors already on it.
I expect it will change the sumptoms. Which just means I have to pretty my spare up, or mess with swapping ignitors & boxes around.
09-12-09, 02:33 AM
#14
Lives on the Forum
Still sounds like an overall grounding issue to me. Maybe (temporarily) run a wire from the engine to the - on the batter just for ***** and giggles?
Sometimes, with a bad ground (or even +) connection, it won't exhibit any symptoms until higher rpms when things start trying to draw (or produce) larger amounts of juice. A trickle can get through, but a large demand just starves out everything that's requesting it...
I dunno, but that's my gut feeling. Sleep well.
Sometimes, with a bad ground (or even +) connection, it won't exhibit any symptoms until higher rpms when things start trying to draw (or produce) larger amounts of juice. A trickle can get through, but a large demand just starves out everything that's requesting it...
I dunno, but that's my gut feeling. Sleep well.
09-12-09, 10:31 AM
#15
Still sounds like an overall grounding issue to me. Maybe (temporarily) run a wire from the engine to the - on the batter just for ***** and giggles?
Sometimes, with a bad ground (or even +) connection, it won't exhibit any symptoms until higher rpms when things start trying to draw (or produce) larger amounts of juice. A trickle can get through, but a large demand just starves out everything that's requesting it...
I dunno, but that's my gut feeling. Sleep well.
Sometimes, with a bad ground (or even +) connection, it won't exhibit any symptoms until higher rpms when things start trying to draw (or produce) larger amounts of juice. A trickle can get through, but a large demand just starves out everything that's requesting it...
I dunno, but that's my gut feeling. Sleep well.
Funny things about the 80 build; the physical structure of the distributor isn't electrically even part of the ground circuit, except for being the ground-point for the ignition coil condenser. The coil positive is routed all the way over to the dizzy just so it can connect to the condenser, which is physically grounded by its mounting tab.
This looks to be a physical design holdover from the 79 points ignition; it makes no electrical sense to route the positive over there just for suppression. Positive voltage is not used on the 80 dizzy at all. But the condenser was physically there for the points ignition, so they left it there for the 80 design.
The pickup coils are fully "floating;" neither side of the pickup coil connection is grounded at all, and even the cable shield does not ground at the distributor end. All electrical grounding for the dizzy is done via the ignitor box grounds - - except for that suppression condenser.
Another strangeness I noticed years ago; the six-pin connector that hooks the pickup coil set to the ignitor box does not appear on the 1980 factory wiring diagram at all. Left completely off the diagram for no apparent reason, as are the cable shields (which are two of the 6 pins). Several of the referenced connectors (like B-24 and B-26) are not shown in the right place on the locator diagram, either, and the ignitor box is missing entirely from the locator diagram.
09-12-09, 01:21 PM
#16
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interesting, if the gauges all do weird things in relation to RPM, and you're having timing/ignition problems, i'd suspect the ignitor/ignitor box. rfi?
09-13-09, 12:31 AM
#17
OK, all is fixed as of about 2pm (working on other stuff since, plus a nice long test drive), and here's the score:
Ignition problem: trailing ignitor was on it's way out.
Swapped to my spare ignitor box (which had two known-good ignitors on it) and flaw went away.
Swapped the suspect trailing ignitor onto it - - problem reapppeared.
Put good ignitor from spare box onto original box - - problem stayed gone.
That was the easy one, once I was sure (as of last night) that it had nothing to do with the other problem, or with my recent mods, it was straightforward.
Now, for the really interesting one: the guage problem.
I was right: the problem was being caused by loss of sender grounds as oil pressure rose.
But I was also wrong: It had nothing to do with the teflon tape.
Follow along, here:
I took the adapter off (easy to do with the new design) and put it on the bench.
Measuring resistance between the two senders, we can see that both have solid, zero-resistance connection through the guage block:
On a hunch, I decided to test resistance on the "skin" of the block:
That's right, the blue anodized coating applied by Racing Beat is NON-conductive
Looking at the part of the unit that bolts to the filter pedestal, you can see that the coating is intact... except for this TINY scratch made by the center fitting when it was originally torqued.
Since the bottom of the adapter is also coated (and seals with an o-ring and smurf snot) the only contact is through the center fitting... and it's only point of contact was that scratch. Both guages were grounding through the tiny scratch's contact with the center fitting, and which only made contact under pressure.
But when oil pressure rose in the filter housing as the engine come up off idle, the fitting is drawn away from the adapter ever so slightly, and the tenuous ground contact is lost.
The ultimate solution, of course, was to polish the coating off of the metal all around the contact area where the center fitting lands:
Presto... put it all back together, and no problems at all.
Since I'd bought some pipe sealant anyway, I went ahead and re-assembled with sealant insead of teflon tape. Looking sharp, now.
Fun, huh?
Ignition problem: trailing ignitor was on it's way out.
Swapped to my spare ignitor box (which had two known-good ignitors on it) and flaw went away.
Swapped the suspect trailing ignitor onto it - - problem reapppeared.
Put good ignitor from spare box onto original box - - problem stayed gone.
That was the easy one, once I was sure (as of last night) that it had nothing to do with the other problem, or with my recent mods, it was straightforward.
Now, for the really interesting one: the guage problem.
I was right: the problem was being caused by loss of sender grounds as oil pressure rose.
But I was also wrong: It had nothing to do with the teflon tape.
Follow along, here:
I took the adapter off (easy to do with the new design) and put it on the bench.
Measuring resistance between the two senders, we can see that both have solid, zero-resistance connection through the guage block:
On a hunch, I decided to test resistance on the "skin" of the block:
That's right, the blue anodized coating applied by Racing Beat is NON-conductive
Looking at the part of the unit that bolts to the filter pedestal, you can see that the coating is intact... except for this TINY scratch made by the center fitting when it was originally torqued.
Since the bottom of the adapter is also coated (and seals with an o-ring and smurf snot) the only contact is through the center fitting... and it's only point of contact was that scratch. Both guages were grounding through the tiny scratch's contact with the center fitting, and which only made contact under pressure.
But when oil pressure rose in the filter housing as the engine come up off idle, the fitting is drawn away from the adapter ever so slightly, and the tenuous ground contact is lost.
The ultimate solution, of course, was to polish the coating off of the metal all around the contact area where the center fitting lands:
Presto... put it all back together, and no problems at all.
Since I'd bought some pipe sealant anyway, I went ahead and re-assembled with sealant insead of teflon tape. Looking sharp, now.
Fun, huh?
09-13-09, 04:17 AM
#18
Uh, DD:
Fun is blasting thru a tunnel on my Ducati and listening to its bark reverb off the walls ....
Fun is basking in the nods from the ricer-boys when I pull up in the Ol' Skule SA
THIS is not fun. You are insane. A genius. But, insane
Congrats on solving 2 real head scratchers...
knock 'em dead at 7stock my friend
Stu Aull
80GS
Alaska
Fun is blasting thru a tunnel on my Ducati and listening to its bark reverb off the walls ....
Fun is basking in the nods from the ricer-boys when I pull up in the Ol' Skule SA
THIS is not fun. You are insane. A genius. But, insane
Congrats on solving 2 real head scratchers...
knock 'em dead at 7stock my friend
Stu Aull
80GS
Alaska
09-13-09, 03:12 PM
#20
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OK, all is fixed as of about 2pm (working on other stuff since, plus a nice long test drive), and here's the score:
Ignition problem: trailing ignitor was on it's way out.
Swapped to my spare ignitor box (which had two known-good ignitors on it) and flaw went away.
Swapped the suspect trailing ignitor onto it - - problem reapppeared.
Put good ignitor from spare box onto original box - - problem stayed gone.
That was the easy one, once I was sure (as of last night) that it had nothing to do with the other problem, or with my recent mods, it was straightforward.
Now, for the really interesting one: the guage problem.
I was right: the problem was being caused by loss of sender grounds as oil pressure rose.
But I was also wrong: It had nothing to do with the teflon tape.
Follow along, here:
I took the adapter off (easy to do with the new design) and put it on the bench.
Measuring resistance between the two senders, we can see that both have solid, zero-resistance connection through the guage block:
On a hunch, I decided to test resistance on the "skin" of the block:
That's right, the blue anodized coating applied by Racing Beat is NON-conductive
Looking at the part of the unit that bolts to the filter pedestal, you can see that the coating is intact... except for this TINY scratch made by the center fitting when it was originally torqued.
Since the bottom of the adapter is also coated (and seals with an o-ring and smurf snot) the only contact is through the center fitting... and it's only point of contact was that scratch. Both guages were grounding through the tiny scratch's contact with the center fitting, and which only made contact under pressure.
But when oil pressure rose in the filter housing as the engine come up off idle, the fitting is drawn away from the adapter ever so slightly, and the tenuous ground contact is lost.
The ultimate solution, of course, was to polish the coating off of the metal all around the contact area where the center fitting lands:
Presto... put it all back together, and no problems at all.
Since I'd bought some pipe sealant anyway, I went ahead and re-assembled with sealant insead of teflon tape. Looking sharp, now.
Fun, huh?
Ignition problem: trailing ignitor was on it's way out.
Swapped to my spare ignitor box (which had two known-good ignitors on it) and flaw went away.
Swapped the suspect trailing ignitor onto it - - problem reapppeared.
Put good ignitor from spare box onto original box - - problem stayed gone.
That was the easy one, once I was sure (as of last night) that it had nothing to do with the other problem, or with my recent mods, it was straightforward.
Now, for the really interesting one: the guage problem.
I was right: the problem was being caused by loss of sender grounds as oil pressure rose.
But I was also wrong: It had nothing to do with the teflon tape.
Follow along, here:
I took the adapter off (easy to do with the new design) and put it on the bench.
Measuring resistance between the two senders, we can see that both have solid, zero-resistance connection through the guage block:
On a hunch, I decided to test resistance on the "skin" of the block:
That's right, the blue anodized coating applied by Racing Beat is NON-conductive
Looking at the part of the unit that bolts to the filter pedestal, you can see that the coating is intact... except for this TINY scratch made by the center fitting when it was originally torqued.
Since the bottom of the adapter is also coated (and seals with an o-ring and smurf snot) the only contact is through the center fitting... and it's only point of contact was that scratch. Both guages were grounding through the tiny scratch's contact with the center fitting, and which only made contact under pressure.
But when oil pressure rose in the filter housing as the engine come up off idle, the fitting is drawn away from the adapter ever so slightly, and the tenuous ground contact is lost.
The ultimate solution, of course, was to polish the coating off of the metal all around the contact area where the center fitting lands:
Presto... put it all back together, and no problems at all.
Since I'd bought some pipe sealant anyway, I went ahead and re-assembled with sealant insead of teflon tape. Looking sharp, now.
Fun, huh?
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