Arcing coil
- Thread starter wtd
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yeah, it could see difference in PEP compared to the rest of the wires, but two things...
Not many tech's either 1- have a scope and 2- know actually what their looking at when they do. Most now adays rely on the computer to tell them what to do.
BTW, It's been awhile, but a long time ago,(giving age away now)... the coil has a red insulated rubber washer that goes in the middle of the cap with a spring that connects the coil to the center lead to the cap. I can't remember, what affect does that have on the system if left out? Also, there's suppose to be a ground strap on that coil to a clip which is directly attached to ground in some way if memory serves.
That's it, the center wire hooks to ground...
Not many tech's either 1- have a scope and 2- know actually what their looking at when they do. Most now adays rely on the computer to tell them what to do.
BTW, It's been awhile, but a long time ago,(giving age away now)... the coil has a red insulated rubber washer that goes in the middle of the cap with a spring that connects the coil to the center lead to the cap. I can't remember, what affect does that have on the system if left out? Also, there's suppose to be a ground strap on that coil to a clip which is directly attached to ground in some way if memory serves.
That's it, the center wire hooks to ground...
Dumb qestion here, but how are the grounds to the body and frame. We know that the ground to the engine block to firewall is new and the ground (assuming from the body) to the thermostat housing is new. But the ground coming out of the battery to the engine, body and frame could be the issue here. I would start with the conections at the battery and follow them. If the main ground to the body or frmae is corroded or even bad battery connections, this will cause the fluccuation in current seen on your guage. That current may be un-naturally flowing through a different path, leading to the ignition problems you are having. I agree with Bob, check your meat-n-potatoes stuff first. 90% of the time it is something simple.
Thanks guys, alot of good input.
Lance,
I can see the white and black wire but it disappears into a huge bundle that is all taped up and has that plastic ribbed stuff on it.
I don't know if the guy scoped the alternator or not. I know my voltage stays at 13.8 My battery is new and I had this same problem with my original battery so I don't think its the battery.
Bob,
An excellent description of what seems to be happening. I haven't really tried to replace one item at a time because a guy that I corresponded with on one of the truck forums said that once one part of the ignition system starts arching, the others will soon follow and I didn't want to start ruining parts. One time I replaced the coil, wires, and plugs and didn't replace the cap & rotor because I had just replaced them not long before, and the truck was still sluggish even though the coil wasn't arching. When I replaced the cap & rotor, the power came back. The truck doesn't misfire and never has stored any misfire codes. My plugs all look fine and are not fouled out, so I doubt that they are the cause. I don't really have any lights that dim while the truck is running, but the airbag on/off switch light, which is always illuminated, flashes with the blinking of the blinkers and is the most noticeable when the headlights are on. The coil on this truck is a remote one and is not physically attached to the cap. It has one plug in and the tower for the coil wire from the distributor cap.
Crashz,
The frame to body ground strap was also replaced at the time I replaced the engine to frame strap. The new braided frame to body strap, which I bought from the dealer, was much bigger than the original strap. As far as I can tell, both my negative and positive battery cable are corrosion free since there is no visable corrosion on the ends. I cleaned and retightend the negative battery cable where it bolts onto the engine block. My battery is fairly new as I replaced it in March of this year.
Thanks again for all of the input.
Wayne
Lance,
I can see the white and black wire but it disappears into a huge bundle that is all taped up and has that plastic ribbed stuff on it.
I don't know if the guy scoped the alternator or not. I know my voltage stays at 13.8 My battery is new and I had this same problem with my original battery so I don't think its the battery.
Bob,
An excellent description of what seems to be happening. I haven't really tried to replace one item at a time because a guy that I corresponded with on one of the truck forums said that once one part of the ignition system starts arching, the others will soon follow and I didn't want to start ruining parts. One time I replaced the coil, wires, and plugs and didn't replace the cap & rotor because I had just replaced them not long before, and the truck was still sluggish even though the coil wasn't arching. When I replaced the cap & rotor, the power came back. The truck doesn't misfire and never has stored any misfire codes. My plugs all look fine and are not fouled out, so I doubt that they are the cause. I don't really have any lights that dim while the truck is running, but the airbag on/off switch light, which is always illuminated, flashes with the blinking of the blinkers and is the most noticeable when the headlights are on. The coil on this truck is a remote one and is not physically attached to the cap. It has one plug in and the tower for the coil wire from the distributor cap.
Crashz,
The frame to body ground strap was also replaced at the time I replaced the engine to frame strap. The new braided frame to body strap, which I bought from the dealer, was much bigger than the original strap. As far as I can tell, both my negative and positive battery cable are corrosion free since there is no visable corrosion on the ends. I cleaned and retightend the negative battery cable where it bolts onto the engine block. My battery is fairly new as I replaced it in March of this year.
Thanks again for all of the input.
Wayne
Hey Bob. Your good pts bring us back to what specific tests were done when the ignition was scoped, specifically if the previously mentioned dynamic tests were actually completed (vs just idling and/or revving the engine).
The Crank KV must be done w/a fully charged batt, fuel pump disabled, and @ WOT. It will heartily, but safely test the 2dary ignition components. If excessive KV is seen, it's possible, afaik, for the truck to initially run fairly well, until the ignition components are inevitably overstressed and then fail
The AC ripple was for possible "noise" interfering with one of the control modules, not V spiking of the coil. And scoping the alternator's VDC will give a more definitive picture of stable output vs a common DMM (w/the poss exception of the most recent/higher-tech/"faster" units).
Wrt the blinkers dimming - Wayne has done some work w/the grnds - but a V-drop of that particular ground circuit would be recommended, as would all the pertinent grounds
I think we are somewhat saying the same things, a bit differently
Lance
The Crank KV must be done w/a fully charged batt, fuel pump disabled, and @ WOT. It will heartily, but safely test the 2dary ignition components. If excessive KV is seen, it's possible, afaik, for the truck to initially run fairly well, until the ignition components are inevitably overstressed and then fail
The AC ripple was for possible "noise" interfering with one of the control modules, not V spiking of the coil. And scoping the alternator's VDC will give a more definitive picture of stable output vs a common DMM (w/the poss exception of the most recent/higher-tech/"faster" units).
Wrt the blinkers dimming - Wayne has done some work w/the grnds - but a V-drop of that particular ground circuit would be recommended, as would all the pertinent grounds
I think we are somewhat saying the same things, a bit differently
Lance
yea and no lance. I'm thinking you all are getting way to deep for a shallow problem when it comes to chasing down this issue. I could even be as simple as he may have a valve problem or leaky injector that is "flooding out" a single plug, and causing it to insulate the ground. (that might be a stretch but possible). With the new plug, it'd work for awhile, but then the insulator can absorb fuel(happened on my harley) and cause it to not fire properly and alot of times not at all, thus creating a high resistance, leading back to current looking for least path ie, grounding out the coil on that one plug.
Anyway, I can tell you're no dummy and really like hearing your points of views and how you go about TS'ing.
BTW, the ripple will exist on the ac side, but DC ripple could also be due to weak battery as it is used as an ac filter as well. Still wondering about the battery and or connection to it.
Anyway, I can tell you're no dummy and really like hearing your points of views and how you go about TS'ing.
BTW, the ripple will exist on the ac side, but DC ripple could also be due to weak battery as it is used as an ac filter as well. Still wondering about the battery and or connection to it.
Wayne - I've got something quite lengthy written up, but for brevity's sake, I wanted to first ask if, when the truck was scoped last year, was that while the coil was arcing? If so, they didn't do it correctly....
Or was it after new ignition components were installed?
Lance
Or was it after new ignition components were installed?
Lance
Lance,
When I had the scope done last year, the coil was arching, but according to him, this was normal, and that everything showed normal on the scope. I do kind of question his abilities because he missed the loose ground wire at the thermostat and I'm the one who found it the day I got it back from him.
A week prior to me taking the truck in to the shop, I had replaced the coil because of arching, but had left the rest of the ignition components in place. Within a week, the new coil was arching, so I took it in. After getting the truck back from the shop and finding the loose ground wire, I replaced the coil, plugs, cap, rotor, and wires again. I thought the problem was fixed because I had tightened the loose ground, but about 3,000 miles later I was getting sluggish performance again and this time found a plug wire arching. I replaced the plug wires again and the ignition coil driver module and didn't have any more problems untill recently, when I found the coil arching again. All of my plug wires are routed so none are touching and I have even used more plug wire holders to ensure this. I also replaced my battery during this time. Thanks for the input.
Wayne
When I had the scope done last year, the coil was arching, but according to him, this was normal, and that everything showed normal on the scope. I do kind of question his abilities because he missed the loose ground wire at the thermostat and I'm the one who found it the day I got it back from him.
A week prior to me taking the truck in to the shop, I had replaced the coil because of arching, but had left the rest of the ignition components in place. Within a week, the new coil was arching, so I took it in. After getting the truck back from the shop and finding the loose ground wire, I replaced the coil, plugs, cap, rotor, and wires again. I thought the problem was fixed because I had tightened the loose ground, but about 3,000 miles later I was getting sluggish performance again and this time found a plug wire arching. I replaced the plug wires again and the ignition coil driver module and didn't have any more problems untill recently, when I found the coil arching again. All of my plug wires are routed so none are touching and I have even used more plug wire holders to ensure this. I also replaced my battery during this time. Thanks for the input.
Wayne
Hi Wayne. More to come later. But for now, an arcing coil would clearly show up on a scope: your secondary ignition firing voltage peaks would be up to double or more than usual.
There are only two "authorized" air gaps in your ignition system, which can be evaluated: rotor to distributor contact(s), and spark plug(s); i.e., the arcing coil, a markedly abnormal air gap, would clearly stand out
There would also likely be excessive KV firing peak variance across all cylinders, due to the variations in how much KV the coil was arcing (each subsequent arc would have a slightly different KV)
It's also sounds v. unlikely the tech performed the specific scope tests stated previously in the thread (amongst others), which IMO would be the quickest & most effective start to getting at the root cause of the problem
Lance
[ October 04, 2003, 10:27 AM: Message edited by: LM ]
There are only two "authorized" air gaps in your ignition system, which can be evaluated: rotor to distributor contact(s), and spark plug(s); i.e., the arcing coil, a markedly abnormal air gap, would clearly stand out
There would also likely be excessive KV firing peak variance across all cylinders, due to the variations in how much KV the coil was arcing (each subsequent arc would have a slightly different KV)
It's also sounds v. unlikely the tech performed the specific scope tests stated previously in the thread (amongst others), which IMO would be the quickest & most effective start to getting at the root cause of the problem
Lance
[ October 04, 2003, 10:27 AM: Message edited by: LM ]
Wayne
I've tried to extol the virtues of having your ignition system critically evaluated w/a scope, by a knowledgeable tech. No guarantees of success - but again think it'd help to get to the _root cause_ of your truck's problem.
A scope basically just graphs voltage against time. A scope can "see" events "faster" - events that go wholly unregistered on common DMMs, scan tools or code readers. The latest scopes have software to reference normal waveforms (or normal is known thru experience).
It's understood that it's sometimes tough to find good tech. I'd look for an electrical diagnostician, on top of being a skilled tech. One who's seen hundreds of ignition waveforms, including your Chevy system, and knows the gamut of tests that can be performed (some listed in my previous posts, as well as some possible _causes_ of failure, along w/other info). Note that some say "scoped" when actually just a scan tool or code reader is used (and not the specific scopes mentioned previously)
I have no first-hand knowledge of them, but their founding premise seems good
http://www.iatn.net/
Their linking 'problems' forum is potentially powerful: maybe an iATN mech has seen your specific problem somewhere
As one of your new coils starting arcing in less than a week, it may have started to fail within minutes/hours after installation. It's unclear whether you have an inductive or CDI coil, or whether the coil is the first ignition component to fail. It looks like the ICM has only been replaced once - if the coil is arcing internally between secondary and primary, as well as the 'to the bracket arc' - the ICM may also be getting damaged. I wouldn't replace the components singularly - that can be helpful in some situations, but don't think this one - and discuss with tech when new ignition components should be installed for scoping (I would think just before)
Per the wiring diagrams - unless I'm missing a critical diagram - it appears G103 and G104 are redundant: they ground _exactly_ the same things
If G104 was less than clean/secure when G103 was loose, it's possible something adverse happened to your system, but otherwise, it seems less likely. Another possibilty is that a wire got nicked, connector partially dislodged, etc., during the intake manifold gasket replacement
It sounds like you've checked most of the basics: your plugs appear to be burning evenly, distrib cap and rotor appear normal, some grounds (but perhaps not all, integral to your ignition system per the wiring diagram) checked, etc. Quick note that the quality of batt and alt testing can vary.
I've PMed you some additional V-drop & ground testing info, some specific to your truck
Other stuff: capacitors can be wired in to filter/block ignition spikes (these are available aftermarket). Your stock system should be well-capable by itself - it likely already has built-in protection - _when_ in good working order. Just a thought - I don't have first-hand knowledge or the experience to say more
Lastly, you mentioned the change w/your distributor: I've only worked w/distrib's that go in to a fixed, not variable depth, so I'm not sure of what to make of that.
Lance
I've tried to extol the virtues of having your ignition system critically evaluated w/a scope, by a knowledgeable tech. No guarantees of success - but again think it'd help to get to the _root cause_ of your truck's problem.
A scope basically just graphs voltage against time. A scope can "see" events "faster" - events that go wholly unregistered on common DMMs, scan tools or code readers. The latest scopes have software to reference normal waveforms (or normal is known thru experience).
It's understood that it's sometimes tough to find good tech. I'd look for an electrical diagnostician, on top of being a skilled tech. One who's seen hundreds of ignition waveforms, including your Chevy system, and knows the gamut of tests that can be performed (some listed in my previous posts, as well as some possible _causes_ of failure, along w/other info). Note that some say "scoped" when actually just a scan tool or code reader is used (and not the specific scopes mentioned previously)
I have no first-hand knowledge of them, but their founding premise seems good
http://www.iatn.net/
Their linking 'problems' forum is potentially powerful: maybe an iATN mech has seen your specific problem somewhere
As one of your new coils starting arcing in less than a week, it may have started to fail within minutes/hours after installation. It's unclear whether you have an inductive or CDI coil, or whether the coil is the first ignition component to fail. It looks like the ICM has only been replaced once - if the coil is arcing internally between secondary and primary, as well as the 'to the bracket arc' - the ICM may also be getting damaged. I wouldn't replace the components singularly - that can be helpful in some situations, but don't think this one - and discuss with tech when new ignition components should be installed for scoping (I would think just before)
Per the wiring diagrams - unless I'm missing a critical diagram - it appears G103 and G104 are redundant: they ground _exactly_ the same things
If G104 was less than clean/secure when G103 was loose, it's possible something adverse happened to your system, but otherwise, it seems less likely. Another possibilty is that a wire got nicked, connector partially dislodged, etc., during the intake manifold gasket replacement
It sounds like you've checked most of the basics: your plugs appear to be burning evenly, distrib cap and rotor appear normal, some grounds (but perhaps not all, integral to your ignition system per the wiring diagram) checked, etc. Quick note that the quality of batt and alt testing can vary.
I've PMed you some additional V-drop & ground testing info, some specific to your truck
Other stuff: capacitors can be wired in to filter/block ignition spikes (these are available aftermarket). Your stock system should be well-capable by itself - it likely already has built-in protection - _when_ in good working order. Just a thought - I don't have first-hand knowledge or the experience to say more
Lastly, you mentioned the change w/your distributor: I've only worked w/distrib's that go in to a fixed, not variable depth, so I'm not sure of what to make of that.
Lance
Lance,
I got your PM and I will try your suggestions. I took my truck to the dealer today to have them look things over and to see if my distributor had been installed correctly after the intake gasket repair. They could find nothing wrong with either my ignition system or anything to do with my blinker circuit. They did say that the reason my airbag switch light was blinking was because it was on a circuit with the blinkers and that under certain voltage loads, it will do what its been doing. The distributor was in correctly and the cam retard offset was at 0 degrees like it was supposed to be. They said everything looked normal and the technicion that drove it, said it had plenty of power and ran better than most of these trucks that he works on. They said that whatever I'm feeling or seeing will have to get alot worse before they can diagnose and fix it. They had it in the back for two hours. Luckily for me, since they could not find anything wrong, they did not charge me anything.
I guess for now, I'll do the tests you recommend and go from there and just drive it untill something breaks.
Wayne
I got your PM and I will try your suggestions. I took my truck to the dealer today to have them look things over and to see if my distributor had been installed correctly after the intake gasket repair. They could find nothing wrong with either my ignition system or anything to do with my blinker circuit. They did say that the reason my airbag switch light was blinking was because it was on a circuit with the blinkers and that under certain voltage loads, it will do what its been doing. The distributor was in correctly and the cam retard offset was at 0 degrees like it was supposed to be. They said everything looked normal and the technicion that drove it, said it had plenty of power and ran better than most of these trucks that he works on. They said that whatever I'm feeling or seeing will have to get alot worse before they can diagnose and fix it. They had it in the back for two hours. Luckily for me, since they could not find anything wrong, they did not charge me anything.
I guess for now, I'll do the tests you recommend and go from there and just drive it untill something breaks.
Wayne
MolaKule
Staff member
wtd,
Did you say that your voltage at idling at the battery was 13.8 volts?
The alternator should be putting out about 14.25 volts or better at idle with all accessories off and the only load being the ignition system and computer.
Did you say that your voltage at idling at the battery was 13.8 volts?
The alternator should be putting out about 14.25 volts or better at idle with all accessories off and the only load being the ignition system and computer.
Disagree Mola, the correct normal loaded vcc is 13.8 at idle, which can vary up to 14.25 depending on that system and load. Both are correct but most times you'll see is 13.8 as the norm.
Molakule,
you are citing a very specific V, and may have specific Chevy/model insight
Generally though, most alternator output V normally can vary between 13.2 V and 14.5 V, depending on a few factors. There should be concern if outside that range (by more than about 0.2 V, I would think)
Agree that 13.8 V - 14.0 V is what should be seen mostly
[ October 08, 2003, 09:39 AM: Message edited by: LM ]
you are citing a very specific V, and may have specific Chevy/model insight
Generally though, most alternator output V normally can vary between 13.2 V and 14.5 V, depending on a few factors. There should be concern if outside that range (by more than about 0.2 V, I would think)
Agree that 13.8 V - 14.0 V is what should be seen mostly
[ October 08, 2003, 09:39 AM: Message edited by: LM ]
MolaKule
Staff member
The four vehicles I have show an average of 14.25 volts at the battery at no-load idle and never less than 13.8 volts at full load (lights on high-beam, AC fan on high, sound system pumping out the Eagles, "Takin It Easy", etc.)
Two are Chevy trucks and two are Nissan vehicles.
If you're tlaking about 13.8 Volts, and since the battery generally has six cells, and
6 X 2.1 volts/cell = 12.6 Volts, this gives a potential of only 1.2 V above quiet battery voltage to pump current into the battery from the alternator.
Two are Chevy trucks and two are Nissan vehicles.
If you're tlaking about 13.8 Volts, and since the battery generally has six cells, and
6 X 2.1 volts/cell = 12.6 Volts, this gives a potential of only 1.2 V above quiet battery voltage to pump current into the battery from the alternator.
Molakule,
It is at 13.8 volts at idle. The only thing that is on is the daytime running lights and my radio, which I never turn off. Its always been at 13.8 as long as I can remember.
Wayne
It is at 13.8 volts at idle. The only thing that is on is the daytime running lights and my radio, which I never turn off. Its always been at 13.8 as long as I can remember.
Wayne
Somebody, anybody, please intervene and change the title of this thread!!! Wouldn't Arcing coil be so much better? I thought it would die out but every time I scan the board I see it and instantly a "picture" of a coil arching through the air as if fired from a mortar is in my fevered brain. So, How about it? Huh, Huh, Huh?
Bless you my son, May your oil remain transparent and your coils remain "arch" free all your days.
MolaKule
Staff member
wtd,
Thanks. I doubt it has anything to do with the problem but it just struck me as being on the low side.
When this arc is occurring, do you hear a snapping sound at all?
BTW, those GM alternators have never been known to be star players. Their voltages really drop off as temps rise.
[ October 09, 2003, 03:51 PM: Message edited by: MolaKule ]
Thanks. I doubt it has anything to do with the problem but it just struck me as being on the low side.
When this arc is occurring, do you hear a snapping sound at all?
BTW, those GM alternators have never been known to be star players. Their voltages really drop off as temps rise.
[ October 09, 2003, 03:51 PM: Message edited by: MolaKule ]
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