Only One Spark
10-14-07, 02:13 PM
#1
Rider of the Sky
Thread Starter
Only One Spark
Going to try posting this again since I'm running out of time to fix this. I've found this question only twice on Google and it's never been answered...
Alright, I got an RX-7 that was sitting for a long time for my brother. It was firing fine but had fuel problems that prevented it from starting. Moments after I fixed that, it stopped sparking normally. When I pull a plug wire and ground a new spark plug as a tester, I only get a single spark out of the leading coils every time I turn the key. Continued cranking gives no sparks. The trailing coils have no activity. The tachometer does not bounce.
Fuses are all good. I've tried replacing the ECU, crank angle sensor, and leading coil pack to no avail. Ideas?
Alright, I got an RX-7 that was sitting for a long time for my brother. It was firing fine but had fuel problems that prevented it from starting. Moments after I fixed that, it stopped sparking normally. When I pull a plug wire and ground a new spark plug as a tester, I only get a single spark out of the leading coils every time I turn the key. Continued cranking gives no sparks. The trailing coils have no activity. The tachometer does not bounce.
Fuses are all good. I've tried replacing the ECU, crank angle sensor, and leading coil pack to no avail. Ideas?
10-14-07, 08:15 PM
#3
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If it sparks once then the coils must have voltage on the black/yellow wire at each coil assy plug.
Seeing as how your about to give up, try this. Obtain a spare CAS and connect it to the plug that is NOW on the engine cas. Key to ON. Do NOT go to START, just key to ON. Now spin the bottom gear of the cas and see if the lead sparkplugs don't spark consistently.
You could remove the cas in the engine and do this same thing as long as you know how to reinstall it back in the same configuration as it is right now.
If it does not spark when doing the above, try this. Remove the plug from the air flow meter. AFM's have been known to kill the five vdc ref voltage in the ECU which in turn means there will be no spark/no fuel injection. You might even try this afm plug removal prior to the cas spin thing. See if the spark improves with the afm plug off.
Seeing as how your about to give up, try this. Obtain a spare CAS and connect it to the plug that is NOW on the engine cas. Key to ON. Do NOT go to START, just key to ON. Now spin the bottom gear of the cas and see if the lead sparkplugs don't spark consistently.
You could remove the cas in the engine and do this same thing as long as you know how to reinstall it back in the same configuration as it is right now.
If it does not spark when doing the above, try this. Remove the plug from the air flow meter. AFM's have been known to kill the five vdc ref voltage in the ECU which in turn means there will be no spark/no fuel injection. You might even try this afm plug removal prior to the cas spin thing. See if the spark improves with the afm plug off.
10-14-07, 09:38 PM
#4
Rider of the Sky
Thread Starter
That sounds like a couple of serious ideas. At the very least, the CAS idea will let me troubleshoot further without killing my starter and battery.
As for the AFM, I never thought of that, but now that you mention it, we were spraying starter fluid in there to try and get the thing going originally, and I noticed after awhile a lot of sludgy crap start pooling at the bottom. I guess there's a chance something could have shorted to the effect of what you describe.
It's not that I'm about to give up, I'm just frustrated and out of time. My brother flies in from Florida tomorrow morning to pick up the car and drive it back (he'll have a companion car with tools should anything go wrong). This issue has had me stunted for weeks; otherwise the car would have been ready to go a long time ago.
I'll update the results later tonight.
As for the AFM, I never thought of that, but now that you mention it, we were spraying starter fluid in there to try and get the thing going originally, and I noticed after awhile a lot of sludgy crap start pooling at the bottom. I guess there's a chance something could have shorted to the effect of what you describe.
It's not that I'm about to give up, I'm just frustrated and out of time. My brother flies in from Florida tomorrow morning to pick up the car and drive it back (he'll have a companion car with tools should anything go wrong). This issue has had me stunted for weeks; otherwise the car would have been ready to go a long time ago.
I'll update the results later tonight.
10-15-07, 03:41 AM
#5
Rider of the Sky
Thread Starter
Ugghhh...
Spinning a removed crank angle sensor by hand gives spark at the ON position, but as soon as it's moved to START and the starter motor cranks the engine, spinning the CAS gives no spark. Trying to start the motor is cutting the ignition. Furthermore, removing the INJ fuse makes the tachometer hover at 1000, and jump all over between 0 and 8000 when the CAS is spun.
Furthermore, the shift up and battery light remain dimly lit even when the key is turned off, and go out when any of the three ecu plugs are removed.
I want to shoot myself.
Spinning a removed crank angle sensor by hand gives spark at the ON position, but as soon as it's moved to START and the starter motor cranks the engine, spinning the CAS gives no spark. Trying to start the motor is cutting the ignition. Furthermore, removing the INJ fuse makes the tachometer hover at 1000, and jump all over between 0 and 8000 when the CAS is spun.
Furthermore, the shift up and battery light remain dimly lit even when the key is turned off, and go out when any of the three ecu plugs are removed.
I want to shoot myself.
Last edited by Delphince; 10-15-07 at 03:54 AM.
10-15-07, 09:16 AM
#6
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I always assumed that if I spin the cas bottom gear and I get good spark from the sparkplug wires/coil, that would mean there is nothing really wrong with the system making spark and that the problem lies with the starter dragging the voltgage down so low that it effects starting. Something like that.
If your checking the spark with a timing light, I'd shy away from that. It's just not sure fire for unknown reasons.
I assume you got spark with the afm's plug on, which is a positive thing, meaning the afm isn't killing the ref voltage of the ECU.
I saw that BATT (or is it ALT? no matter) light once about a month ago on one of my cars. Puzzled the heck out of me. Car drove fine and that light went out and it didn't come back. I considered that an anomaly. Can't trouble shoot what isn't broke.
It's possible the engine is severly flooded and even starter fluid isn't working. Might try getting some oil in the rotor chambers and trying again.
A little note here: The afm is not used for the START cycle. The ECU uses an internal start map so to speak. That map uses rpm under 500, water thermo sensor input and the 12vdc start signal on pin 3B (series four) to determine fuel delivery. Once over 500 rpm the ECU uses the afm signal for fuel delivery.
If the water thermo signal is not seen by the ECU (as in the plug off the water thermo sensor), the water thermo signal is deffaulted to 179* F. That is not good for a cold engine because that Start Map will see 179*F and deliver too little fuel for the cold engine and makes starting difficult. Once the engine gets hot though, the default of 179* matters not during Start because the engine isn't cold anymore and 179*F is just fine and the engine will start fine for the rest of the day. Once cooled off though, your back to square one again.
That has probably not much to do with your car, but might help in the future once you realize the afm has squat to do with the initial Start of the engine (talking the first few seconds of the engine actually starting). And might help to know the part about the water thermos sensors part in Starting the engine and how when IT sees a cold engine it feeds more fuel during start than when it sees a hot engine. Cold engines need more fuel than hot engines for easier starting.
If your checking the spark with a timing light, I'd shy away from that. It's just not sure fire for unknown reasons.
I assume you got spark with the afm's plug on, which is a positive thing, meaning the afm isn't killing the ref voltage of the ECU.
I saw that BATT (or is it ALT? no matter) light once about a month ago on one of my cars. Puzzled the heck out of me. Car drove fine and that light went out and it didn't come back. I considered that an anomaly. Can't trouble shoot what isn't broke.
It's possible the engine is severly flooded and even starter fluid isn't working. Might try getting some oil in the rotor chambers and trying again.
A little note here: The afm is not used for the START cycle. The ECU uses an internal start map so to speak. That map uses rpm under 500, water thermo sensor input and the 12vdc start signal on pin 3B (series four) to determine fuel delivery. Once over 500 rpm the ECU uses the afm signal for fuel delivery.
If the water thermo signal is not seen by the ECU (as in the plug off the water thermo sensor), the water thermo signal is deffaulted to 179* F. That is not good for a cold engine because that Start Map will see 179*F and deliver too little fuel for the cold engine and makes starting difficult. Once the engine gets hot though, the default of 179* matters not during Start because the engine isn't cold anymore and 179*F is just fine and the engine will start fine for the rest of the day. Once cooled off though, your back to square one again.
That has probably not much to do with your car, but might help in the future once you realize the afm has squat to do with the initial Start of the engine (talking the first few seconds of the engine actually starting). And might help to know the part about the water thermos sensors part in Starting the engine and how when IT sees a cold engine it feeds more fuel during start than when it sees a hot engine. Cold engines need more fuel than hot engines for easier starting.
10-15-07, 09:22 AM
#7
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If this is a non turbo car, you might try to pour a cup of oil in the intake and spin the engine over for maybe ten/fifteen seconds with the EGI fuses pulled out. That might restore the compression enough where when you reinstall the EGI fuses and spray starter fluid in the intake (just two seconds of spray is enough), it might start.
That's if severe flooding is the problem.
Sorry, I've never looked at the tach when spinning the cas bottom gear. I can't relate to that. I'm just convinced the ability to make spark is there and there is nothing wrong with the coils.
That's if severe flooding is the problem.
Sorry, I've never looked at the tach when spinning the cas bottom gear. I can't relate to that. I'm just convinced the ability to make spark is there and there is nothing wrong with the coils.
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10-15-07, 09:27 AM
#8
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Here's the Chart I was referring to: https://www.rx7club.com/forum/attach...6&d=1182728184
10-15-07, 09:34 AM
#9
Rider of the Sky
Thread Starter
Flooding isn't the issue. I've been mindful to yank the fuse every few seconds to air it back out when we do crank, but the main focus right now is trying to figure out why the spark system is completely cutting out on startup, as well as the perpetually dim shift and batt light when the key is off. Battery voltage is more than adequate.
I'm not using a timing light, I'm using a new fifth spark plug grounded to the manifold and one of the leading coil wires when checking for spark.
I'm not using a timing light, I'm using a new fifth spark plug grounded to the manifold and one of the leading coil wires when checking for spark.
10-15-07, 09:54 AM
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Well, when the engine is not running, all the dash lights should be ON. Not just one or two lights on.
What is SUPPOSED to happen, is the WHITE/BLACK wire on the alt small plug will put out a GROUND signal if the alt is not turning over. That gnd signal goes to a relay in the CPU. The relay pulls in when that gnd is put on it and that relay.
That relay in the CPU pulls in and in turn puts a gnd on the warning light cluster and the shift light. All the warning lights are supposed to come on when that happens. The shift light being on is normal also.
Why don't all the warning lights come on????? Probably a solder problem with the contacts on the warning light clusters plug. Well, with the pins that mate with that plug. The pins on the warning light unit itself. In other words........don't worry about this *problem* your seening.
When the alt is turning over and producing, there will not be a gnd on that White/Black anymore, so the warning lights go off. Normal operation.
Try starting wth the afm plug off just once and see if things change?????
What is SUPPOSED to happen, is the WHITE/BLACK wire on the alt small plug will put out a GROUND signal if the alt is not turning over. That gnd signal goes to a relay in the CPU. The relay pulls in when that gnd is put on it and that relay.
That relay in the CPU pulls in and in turn puts a gnd on the warning light cluster and the shift light. All the warning lights are supposed to come on when that happens. The shift light being on is normal also.
Why don't all the warning lights come on????? Probably a solder problem with the contacts on the warning light clusters plug. Well, with the pins that mate with that plug. The pins on the warning light unit itself. In other words........don't worry about this *problem* your seening.
When the alt is turning over and producing, there will not be a gnd on that White/Black anymore, so the warning lights go off. Normal operation.
Try starting wth the afm plug off just once and see if things change?????
10-15-07, 10:11 AM
#11
Rider of the Sky
Thread Starter
Well, when the engine is not running, all the dash lights should be ON. Not just one or two lights on.
[...]
Why don't all the warning lights come on????? Probably a solder problem with the contacts on the warning light clusters plug. Well, with the pins that mate with that plug. The pins on the warning light unit itself. In other words........don't worry about this *problem* your seening.
[...]
Why don't all the warning lights come on????? Probably a solder problem with the contacts on the warning light clusters plug. Well, with the pins that mate with that plug. The pins on the warning light unit itself. In other words........don't worry about this *problem* your seening.
I did the AFM thing last night. We got spark in both cases as long as we weren't trying to start the car.
10-15-07, 01:32 PM
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The shift up light gets it power from the Meter fuse but needs a gnd from either the ECU's large plug or the relay I mentioned earlier in the CPU.
Couple of things you might try. Pull the METER fuse next time this happens and see what the results are. OR pull the large plug off the ECU and see what happens.
Or wiggle the ignition key to see what happens. The meter fuse should not see power unless the key is to Ign (on).
Which makes me wonder a bit about the ignition key and life in general. You say that you have spark turning the cas bottom gear with the key On (Ign) but not to START.
Well, maybe your losing a dc bus when you go to Start???? Losing the power to the ENGINE fuse is what I'm suggesting. The ENGINE fuse is required to pull in the Main Relay and supply power to the fuel pump. Main Relay has to be pulled in to feed power to the ECU which in turn supplys spark/fuel injector pulsing.
I'm suggesting this. PUll the Trai coil up and out of the way. Just the three nuts that hold it down. No need to pull any wires off it.
Look for a very bright BLUE connector that has a jumper wire in it going across two pins. PUll that blue half of the connector off and lay it to the side. The other half should have a black/white wire that was opposite one end of the jumper that you pulled off. That black/white wire goes to the starter solenoid. If you apply batt voltage to that black/white wire the starter will turn over without the key being turned at all.
So grab a piece of wire that will reach from the batt positive terminal to that black/white wire in the plug mentioned above. CAr in NEUTRAL. Mometarily touch that wire to the black/white wire (other end attached to the batt positive terminal). The starter should turn over for that MOMENT, proving you have the right black/white wire.
So, now turn the key to On but NOT to Start. Go back to the engine bay and touch the new wire to the black/white wire so the starter will spin. Now watch your test sparkplug to see if you have consistent spark. If you do, then there is something amiss with the ignition switch.
IF you have Theft Protection that blue connector with the single wire jumper in it won't exist. You'd have to find the relay that is in the car that replaces that bright blue jumper plug. It should be near the Main Relay I THINK.
Any of that make sense???? The idea is to have the igniton switch in the On position where you've seen good spark and to leave that ignition switch in that position while you HOT WIRE the starter to spin the engine over. Car should start like this. My car does. Yous should also. I use that jumper while working in the engine bay and don't wanna have to go to the interior to turn a key to start the engine.
No bright blue plug? Got theft protection? Let me know and I can give you the colors in the plug that is attached to the theft relay (goes by another name in the FSM, called Starter Cut Relay).
Couple of things you might try. Pull the METER fuse next time this happens and see what the results are. OR pull the large plug off the ECU and see what happens.
Or wiggle the ignition key to see what happens. The meter fuse should not see power unless the key is to Ign (on).
Which makes me wonder a bit about the ignition key and life in general. You say that you have spark turning the cas bottom gear with the key On (Ign) but not to START.
Well, maybe your losing a dc bus when you go to Start???? Losing the power to the ENGINE fuse is what I'm suggesting. The ENGINE fuse is required to pull in the Main Relay and supply power to the fuel pump. Main Relay has to be pulled in to feed power to the ECU which in turn supplys spark/fuel injector pulsing.
I'm suggesting this. PUll the Trai coil up and out of the way. Just the three nuts that hold it down. No need to pull any wires off it.
Look for a very bright BLUE connector that has a jumper wire in it going across two pins. PUll that blue half of the connector off and lay it to the side. The other half should have a black/white wire that was opposite one end of the jumper that you pulled off. That black/white wire goes to the starter solenoid. If you apply batt voltage to that black/white wire the starter will turn over without the key being turned at all.
So grab a piece of wire that will reach from the batt positive terminal to that black/white wire in the plug mentioned above. CAr in NEUTRAL. Mometarily touch that wire to the black/white wire (other end attached to the batt positive terminal). The starter should turn over for that MOMENT, proving you have the right black/white wire.
So, now turn the key to On but NOT to Start. Go back to the engine bay and touch the new wire to the black/white wire so the starter will spin. Now watch your test sparkplug to see if you have consistent spark. If you do, then there is something amiss with the ignition switch.
IF you have Theft Protection that blue connector with the single wire jumper in it won't exist. You'd have to find the relay that is in the car that replaces that bright blue jumper plug. It should be near the Main Relay I THINK.
Any of that make sense???? The idea is to have the igniton switch in the On position where you've seen good spark and to leave that ignition switch in that position while you HOT WIRE the starter to spin the engine over. Car should start like this. My car does. Yous should also. I use that jumper while working in the engine bay and don't wanna have to go to the interior to turn a key to start the engine.
No bright blue plug? Got theft protection? Let me know and I can give you the colors in the plug that is attached to the theft relay (goes by another name in the FSM, called Starter Cut Relay).
10-15-07, 01:35 PM
#14
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By the way, the Trail and Lead coils need to be bolted to the chassis with at least one bolt for the ignitor in them to cause spark. So once you access the blue jumper connector, try to put the Trail coil back with at least one hold down bolt. ALTHOUGH the trail coil is NOT needed to start a RX-7 .
Does this car have an unusual history??? Harnesses swapped out at some time? Fuse boxes swapped out at sometime?? Anything like that? N/a to turbo????
Does this car have an unusual history??? Harnesses swapped out at some time? Fuse boxes swapped out at sometime?? Anything like that? N/a to turbo????
10-15-07, 03:29 PM
#16
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I actually like the idea the igniton sw is the problem.
There is an easier way than the things I mentioned above. Just pull the LARGE plug off the Main Relay. Make two jumper wires. Jumper the black/yellow to the Black/Green. Then jumper the white/blue to the Black/White wire.
Once you do that, you've done all that is required for the ECU/cols assy's to get power and the fuel pump to get power. All you do now is go to the key and go to START and watch your test sparkplug for fire or not. Turning the key with the jumpers, overrides any malfunctioning ignition switch.
Dont worry about the other plug on the Main Relay. Those are not players if the other four wires are jumpered in the other Main Relay plug. Good luck.
There is an easier way than the things I mentioned above. Just pull the LARGE plug off the Main Relay. Make two jumper wires. Jumper the black/yellow to the Black/Green. Then jumper the white/blue to the Black/White wire.
Once you do that, you've done all that is required for the ECU/cols assy's to get power and the fuel pump to get power. All you do now is go to the key and go to START and watch your test sparkplug for fire or not. Turning the key with the jumpers, overrides any malfunctioning ignition switch.
Dont worry about the other plug on the Main Relay. Those are not players if the other four wires are jumpered in the other Main Relay plug. Good luck.
10-15-07, 04:23 PM
#17
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OR try this. You know you have spark if the cas bottom gear is spun. So. Do that again, but as you spin the bottom gear and watch spark, have someone turn the key to Start and see if spark is still there.
To be clear. IF your clutch interlock switch is still functioning, then if someone turns the key to START and does not depress the clutch, the starter will not turn over but if there is an anomaly with the ignition switch, then you will not be able to get spark anymore from spinning the CAS. It should give you a clue.
If it turns out you have no spark with the key to Start, then go back to my thread above this one where I suggest pulling the large Main Relay plug off and jumpering the four wires in it. Then try, try, try again (Neville Chamberlins very words).
To be clear. IF your clutch interlock switch is still functioning, then if someone turns the key to START and does not depress the clutch, the starter will not turn over but if there is an anomaly with the ignition switch, then you will not be able to get spark anymore from spinning the CAS. It should give you a clue.
If it turns out you have no spark with the key to Start, then go back to my thread above this one where I suggest pulling the large Main Relay plug off and jumpering the four wires in it. Then try, try, try again (Neville Chamberlins very words).
10-16-07, 10:37 AM
#18
Rider of the Sky
Thread Starter
I've got a lot you've given me here to sponge in, but I'll answer as much as I can while I give these things a try, though I have a new problem.
I said #@$% it and pulled an entire ignition/primary harness from another car of the same year, and replaced the one in the car. It turns out there are minor differences (wtf) between the two even though they are both early 86s and now the starter won't work. So I have to undo it all and put in the old one.
But here's what I was getting for the ECU plugs: Going from left to right, you have plug 1, 2, and 3; 3 being the large one for the main harness. If I pulled 3, the problem lights would go out. If I pulled either 1 OR 2, nothing would change. If I pulled BOTH 1 and 2, the lights would go out. This led me to believe the short is coming from somewhere in the engine harness, but since the battery is only connected to the main harness, my more knowledgeable friend assisting me insisted this wasn't possible. Now though it would seem I'm running out of places to look.
Speaking of security, there is one other thing I failed to mention, because I just wrote it off as being part of the door switches sitting so long. If I pulled the main fuse to kill the power to the trouble lights (they didn't glow unless the key was turned to OFF from ON), any time the key was removed the security light would flash rapidly (about 2 times per second) and never stop until the battery is disconnected, and the power locks in the doors (driver lock goes down or up, passenger follows suit) wouldn't function.
I remember a bright blue plug; the only one in the I can remember being on the engine bay side. It plugged into a relay with a bright blue female end.
Clutch switch: the car would attempt to crank without depressing the clutch or being in neutral. I chalked this up again to an aged safety switch somewhere. Mixed up in my previous posts I mentioned that I tried this somewhere: I spun the CAS by hand while the key was turned to START and it would make no spark, contrary to the spark it would make in the ON position.
I avoided hotwiring the starter from the get-go because if it did work, it still wouldn't have made a drivable car, and continued to focus on finding the problem.
Edit: In addition to the new harness not marrying up, if I didn't make the point clear, it did NOT fix any of the existing problems. And when I say new harness, I mean the whole shabang-- ECU, all accessory computers, ignition switch, gauge cluster (with tachometer), idiot cluster, fuse boxes, and the harness itself. The only things that didn't get swapped out were engine accessories and the engine harness.
I said #@$% it and pulled an entire ignition/primary harness from another car of the same year, and replaced the one in the car. It turns out there are minor differences (wtf) between the two even though they are both early 86s and now the starter won't work. So I have to undo it all and put in the old one.
But here's what I was getting for the ECU plugs: Going from left to right, you have plug 1, 2, and 3; 3 being the large one for the main harness. If I pulled 3, the problem lights would go out. If I pulled either 1 OR 2, nothing would change. If I pulled BOTH 1 and 2, the lights would go out. This led me to believe the short is coming from somewhere in the engine harness, but since the battery is only connected to the main harness, my more knowledgeable friend assisting me insisted this wasn't possible. Now though it would seem I'm running out of places to look.
Speaking of security, there is one other thing I failed to mention, because I just wrote it off as being part of the door switches sitting so long. If I pulled the main fuse to kill the power to the trouble lights (they didn't glow unless the key was turned to OFF from ON), any time the key was removed the security light would flash rapidly (about 2 times per second) and never stop until the battery is disconnected, and the power locks in the doors (driver lock goes down or up, passenger follows suit) wouldn't function.
I remember a bright blue plug; the only one in the I can remember being on the engine bay side. It plugged into a relay with a bright blue female end.
as you spin the bottom gear and watch spark, have someone turn the key to Start and see if spark is still there.
To be clear. IF your clutch interlock switch is still functioning, then if someone turns the key to START and does not depress the clutch, the starter will not turn over but if there is an anomaly with the ignition switch, then you will not be able to get spark anymore from spinning the CAS.
To be clear. IF your clutch interlock switch is still functioning, then if someone turns the key to START and does not depress the clutch, the starter will not turn over but if there is an anomaly with the ignition switch, then you will not be able to get spark anymore from spinning the CAS.
I avoided hotwiring the starter from the get-go because if it did work, it still wouldn't have made a drivable car, and continued to focus on finding the problem.
Edit: In addition to the new harness not marrying up, if I didn't make the point clear, it did NOT fix any of the existing problems. And when I say new harness, I mean the whole shabang-- ECU, all accessory computers, ignition switch, gauge cluster (with tachometer), idiot cluster, fuse boxes, and the harness itself. The only things that didn't get swapped out were engine accessories and the engine harness.
Last edited by Delphince; 10-16-07 at 11:03 AM.
10-16-07, 11:17 AM
#19
Rider of the Sky
Thread Starter
In retrospect I'm not sure about the bright blue plug--I know for sure it's on the new harness we just put in that needs to come out, but I don't remember if it was on the old one. I'll know soon enough when I drive over and look.
As for the car's history, I can't say. The guy I bought it from clearly lied about how long it was sitting in his garage and probably the part about him driving it there as well, so even if I had--and I didn't--received any other information it would have been at a grain of salt.
Bleh, this whole situation is actually making me roll my eyes at the first line of my own sig...
As for the car's history, I can't say. The guy I bought it from clearly lied about how long it was sitting in his garage and probably the part about him driving it there as well, so even if I had--and I didn't--received any other information it would have been at a grain of salt.
Bleh, this whole situation is actually making me roll my eyes at the first line of my own sig...
10-16-07, 11:52 AM
#20
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Well, forget about the Blue plug and use the alternate idea I posted after that idea. The one where you go to the Main Relay (in the area of the Trail Coil assy area of the engine bay) and pull the large plug off that Main Relay. Make two jumper wires and jumper the sockets I recommended in that earlier post.
Once you jumper those sockets the ECU and fuel pump will have power. Then put the key to ON (or Ign, I forget the right name). Spin that bottom gear on the cas and look at the consistent spark. THEN have someone HOLD the key to START (but don't push the clutch in while doing so, so the starter won't turn over) while you spin the cas. See if the spark is still there or not.
IF the spark is still there, what I'd do is reinstall the cas and leave the jumper wires in place at the Main Relay. Then try starting the engine.
Having those jumper wires in the Main Relay should negate any effect turning of the igniton key to Start WAS having on the power to the ECu/COILS.
So forget the Blue jumper plug and try the jumpiing of the Main RElay's plug. The Main Relay has two connectors. The one with just two wires is not a player. You can leave it connected or remove it from the Main Relay.
IF for some reason this is one of those cars that you do not have to push the clutch in to get the starter to work, say so because we need to overcome that in the above procedure where you spin the cas gear with the jumpers in.
Once you jumper those sockets the ECU and fuel pump will have power. Then put the key to ON (or Ign, I forget the right name). Spin that bottom gear on the cas and look at the consistent spark. THEN have someone HOLD the key to START (but don't push the clutch in while doing so, so the starter won't turn over) while you spin the cas. See if the spark is still there or not.
IF the spark is still there, what I'd do is reinstall the cas and leave the jumper wires in place at the Main Relay. Then try starting the engine.
Having those jumper wires in the Main Relay should negate any effect turning of the igniton key to Start WAS having on the power to the ECu/COILS.
So forget the Blue jumper plug and try the jumpiing of the Main RElay's plug. The Main Relay has two connectors. The one with just two wires is not a player. You can leave it connected or remove it from the Main Relay.
IF for some reason this is one of those cars that you do not have to push the clutch in to get the starter to work, say so because we need to overcome that in the above procedure where you spin the cas gear with the jumpers in.
10-16-07, 08:25 PM
#21
Rider of the Sky
Thread Starter
Ok, tried one of your earlier ideas about bridging the starter since I know the fuel pump is working. I avoided it because I wanted to fix the car, not find a work around. But I caved. The result was more than a little suprising...
The key was turned to ON. This gives a spark when the CAS is removed and turned by hand. While I was spinning it, I had someone bridge the starter to crank the car. The sparks cut out, just as before! The ecu should have no say in the matter what-so-ever at that point, so there is nothing to turn off the coils. The act of running power to the starter from the battery is disrupting the CAS signal. Sounds related to that cross I kept mentioning. I'll know more in a bit.
10-16-07, 08:45 PM
#22
HAILERS
Join Date: May 2001
Location: FORT WORTH, TEXAS,USA
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How 'bout this. Reach under the car and pull the small wire off the starter. The one on a blade.
Key ON. Watch the spark as you spin the cas. Then have the other guy hold the key to START. Still got spark???? Starter should not be turning over as you do that because you pulled the small wire off the starter solenoid.
Not to woryy. It's a bad habit of mine to not read everything in a post. I've a lot of preconcieved notions.
Some of this is redundant though, since you did not turn the key to Start earlier and bridged the starter to work. Oh well.
Key ON. Watch the spark as you spin the cas. Then have the other guy hold the key to START. Still got spark???? Starter should not be turning over as you do that because you pulled the small wire off the starter solenoid.
Not to woryy. It's a bad habit of mine to not read everything in a post. I've a lot of preconcieved notions.
Some of this is redundant though, since you did not turn the key to Start earlier and bridged the starter to work. Oh well.
10-16-07, 11:28 PM
#23
Rider of the Sky
Thread Starter
Attempted with CAS turned by hand:
--Solenoid wire removed--
ON position: spark.
START position: no spark.
Return to ON position: no spark.
--Solenoid wire removed, middle ECU plug removed--
ON position: spark.
START position: no spark.
Return to ON position: spark.
Starter positive disconnected and bridged with cables run from battery--
ON position: spark.
START position: no spark.
Return to ON position: spark.
Starter completely disconnected and bridged with cables from battery--
ON position: spark.
Bridged with screwdriver: no spark.
Bridge with screwdriver canceled: spark.
None of this made a whole lot of sense. Out as a last resort, I pulled out my last spare ecu of the same # that I was saving in case ECUs were being killed by this car somehow. We hooked it up, and tried the first trial again, and got this:
--Solenoid wire removed--
ON position: spark.
START position: spark.
Return to ON position: spark.
It looked good, and hooked everything back up the way it should, including reconnecting the engine CAS. We kept one lead plug wire grounded to a test though, to check for spark. As soon as the engine cranked, we got no spark. I quickly checked the ecu, and it smelled rancid. I thought it was dead, but a repeat of the solenoid-disconnected test had sparks in all three key checks again, so I think it survived. Something is feeding power into the ecu when the starter and/or solenoid is energized through stock wiring.
--Solenoid wire removed--
ON position: spark.
START position: no spark.
Return to ON position: no spark.
--Solenoid wire removed, middle ECU plug removed--
ON position: spark.
START position: no spark.
Return to ON position: spark.
Starter positive disconnected and bridged with cables run from battery--
ON position: spark.
START position: no spark.
Return to ON position: spark.
Starter completely disconnected and bridged with cables from battery--
ON position: spark.
Bridged with screwdriver: no spark.
Bridge with screwdriver canceled: spark.
None of this made a whole lot of sense. Out as a last resort, I pulled out my last spare ecu of the same # that I was saving in case ECUs were being killed by this car somehow. We hooked it up, and tried the first trial again, and got this:
--Solenoid wire removed--
ON position: spark.
START position: spark.
Return to ON position: spark.
It looked good, and hooked everything back up the way it should, including reconnecting the engine CAS. We kept one lead plug wire grounded to a test though, to check for spark. As soon as the engine cranked, we got no spark. I quickly checked the ecu, and it smelled rancid. I thought it was dead, but a repeat of the solenoid-disconnected test had sparks in all three key checks again, so I think it survived. Something is feeding power into the ecu when the starter and/or solenoid is energized through stock wiring.
10-16-07, 11:44 PM
#24
Rider of the Sky
Thread Starter
Ok, this was the last test. We disconnected the starter from the harness. We ran a heavy cable from the battery(+) to the starter poles, and a wire from the solenoid switch. The starter now had power but was not receiving it through the harness. Spinning the CAS by hand:
ON position: spark.
START position: spark.
Return to ON position: spark.
Now, leaving the key in the ON position, we touched the solenoid wire to the battery terminal. The engine started to crank. No spark. We removed the solenoid wire. Engine stopped cranking. Spark.
So we got a second battery and ran both a positive and a ground between the starter and the battery, leaving the original battery still hooked up in the car normally. We turned the key to the ON position and touched the solenoid wire we ran to battery#2. Engine cranked and SPARK!
What is going on here?!
ON position: spark.
START position: spark.
Return to ON position: spark.
Now, leaving the key in the ON position, we touched the solenoid wire to the battery terminal. The engine started to crank. No spark. We removed the solenoid wire. Engine stopped cranking. Spark.
So we got a second battery and ran both a positive and a ground between the starter and the battery, leaving the original battery still hooked up in the car normally. We turned the key to the ON position and touched the solenoid wire we ran to battery#2. Engine cranked and SPARK!
What is going on here?!
Last edited by Delphince; 10-16-07 at 11:56 PM.
10-17-07, 12:28 AM
#25
HAILERS
Join Date: May 2001
Location: FORT WORTH, TEXAS,USA
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*****I said #@$% it and pulled an entire ignition/primary harness from another car of the same year, and replaced the one in the car. It turns out there are minor differences (wtf) between the two even though they are both early 86s and now the starter won't work. So I have to undo it all and put in the old one.
************************************************** ***************
I think this is because some of the early cars did not have a clutch interlock switch, which meant they didn't need the clutch depressed to start. Later cars have that interlock switch and the clutch has to be drpressed to start. It sounds like that is what the difference is b/t those two harness. Even some 87 had no clutch interlock switch. Some, not all, some.
Right now there only useful thing I can think of doing, is getting a meter out and going to the ECU plugs. Backprobe each wire for the value given in the Fuel section. A page called Control Unit.
What number ECU are you using? It should be N326 or N327.
I don't think I should mention the shadetree idea, but..........how about another battery? Like a second battery devolted to the starter. Not for long time use but just to finally hear that engnine turn over by itself? Sort of a moral booster thing.
************************************************** **********
But here's what I was getting for the ECU plugs: Going from left to right, you have plug 1, 2, and 3; 3 being the large one for the main harness. If I pulled 3, the problem lights would go out. If I pulled either 1 OR 2, nothing would change. If I pulled BOTH 1 and 2, the lights would go out. This led me to believe the short is coming from somewhere in the engine harness, but since the battery is only connected to the main harness, my more knowledgeable friend assisting me insisted this wasn't possible. Now though it would seem I'm running out of places to look.
************************************************** ************
There is a pin (pin 1K, a black/red wire) on the large plug of the ECU that puts a gnd on the Shift Up Light when the car is running and at some??? given time. You might try to depin that wire and tape it off so it won't touch anything. Then see if the lights go away. Should be on the top row, about the sixth one over from the right.
I'm curious. I wonder. The Lead coil assy has a small two wire plug. One of the wires is Black/Yellow. That is 12vdc for the coil assy. The other wire triggers the coil ignitor. Forget the trigger wire. If possible, put a meter on the black/yellow wire. Key ON. You should see batt voltage. Put the key to START and let the starter turn the engine over. Does the battery voltage stay on the black/yellow wire as the engine is spun with the starter??? Not that I can think of anyway it would disappear, but....I wonder.
I wonder if it's the lack of a trigger signal from the ECU or the lack of 12vdc at the coil assy's black/yellow wire.
I'll reread you last few posts again, although I already have. Maybe come up with some other idea.
N326? Any chance someone has stuck a Turbo engine (really EM harness) harness on the engine. All the solenoids seem to match up? No spare plugs laying around looking for a home? I'm trying to think of a sure way to tell. The turbo EM harness has a Green solenoid plug on the left side of the engine bay.
************************************************** ***************
I think this is because some of the early cars did not have a clutch interlock switch, which meant they didn't need the clutch depressed to start. Later cars have that interlock switch and the clutch has to be drpressed to start. It sounds like that is what the difference is b/t those two harness. Even some 87 had no clutch interlock switch. Some, not all, some.
Right now there only useful thing I can think of doing, is getting a meter out and going to the ECU plugs. Backprobe each wire for the value given in the Fuel section. A page called Control Unit.
What number ECU are you using? It should be N326 or N327.
I don't think I should mention the shadetree idea, but..........how about another battery? Like a second battery devolted to the starter. Not for long time use but just to finally hear that engnine turn over by itself? Sort of a moral booster thing.
************************************************** **********
But here's what I was getting for the ECU plugs: Going from left to right, you have plug 1, 2, and 3; 3 being the large one for the main harness. If I pulled 3, the problem lights would go out. If I pulled either 1 OR 2, nothing would change. If I pulled BOTH 1 and 2, the lights would go out. This led me to believe the short is coming from somewhere in the engine harness, but since the battery is only connected to the main harness, my more knowledgeable friend assisting me insisted this wasn't possible. Now though it would seem I'm running out of places to look.
************************************************** ************
There is a pin (pin 1K, a black/red wire) on the large plug of the ECU that puts a gnd on the Shift Up Light when the car is running and at some??? given time. You might try to depin that wire and tape it off so it won't touch anything. Then see if the lights go away. Should be on the top row, about the sixth one over from the right.
I'm curious. I wonder. The Lead coil assy has a small two wire plug. One of the wires is Black/Yellow. That is 12vdc for the coil assy. The other wire triggers the coil ignitor. Forget the trigger wire. If possible, put a meter on the black/yellow wire. Key ON. You should see batt voltage. Put the key to START and let the starter turn the engine over. Does the battery voltage stay on the black/yellow wire as the engine is spun with the starter??? Not that I can think of anyway it would disappear, but....I wonder.
I wonder if it's the lack of a trigger signal from the ECU or the lack of 12vdc at the coil assy's black/yellow wire.
I'll reread you last few posts again, although I already have. Maybe come up with some other idea.
N326? Any chance someone has stuck a Turbo engine (really EM harness) harness on the engine. All the solenoids seem to match up? No spare plugs laying around looking for a home? I'm trying to think of a sure way to tell. The turbo EM harness has a Green solenoid plug on the left side of the engine bay.