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Steve M.
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Joined: July 30, 2013
Posts: 6832
Location: Fort Lauderdale, Fl.
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 Posted: Mon Jul 10, 2023 4:51 am Post subject: Weak spark to disappearing spark? |
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Okay my other recent post regarding Ignition Coils was because of this new problem.
50 mile drive engine felt slightly rough the last few miles. Pulled of the interstate and promptly died atfter 2 intersections.
No restart.
Got it towed back to the marina and did all the Pro-training diagnostics of the ECU pins and fuel system. All within specs.
Set up the smartfone video and saw that there was spark from a plug, but did it
not look strong. Had a passing southy look at them as they always stop to check out the Syncro and he saw spark, but he really didn't understand what he was looking at.
My first video the the spark did not seem to last as long as the engine was cranking. I couldn't really tell because the darkness at night in engine compartment from the time I stopped cranking and got back to turn off the video.
My 3rd video of the spark plug vise-gripped to the alternator flange with more light in the engine compartment showed no spark at all.(spare old plug, not the one in the cylinder.)
So where did my spark go?
Checking all the ground wires tonight and replacing the the terminal ends as corrosion gets into the wires. The ignition coil btw way tested good at .8 on the primary and 2.74 on the secondary. It is maybe 6 months old. New one from GoWesty on the way just in case it is really bad.
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Chilepines
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Joined: October 11, 2022
Posts: 142
Location: New Hampshire
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| Posted: Mon Jul 10, 2023 5:10 am Post subject: Re: Weak spark to disappearing spark? |
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When our van died right after we bought it, it went from running fine with some stalling, to then crank with no start. Mechanic found 8V at the ignition and traced it back to the D15 pin in the fuse panel. The circuit was overloaded by VW and burns out over time.
Our van has a 2.5 Subaru. I’ve seen others on here who found a problem at different fuse going to the ignition.
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MarkWard
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Joined: February 09, 2005
Posts: 17153
Location: Retired South Florida
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| Posted: Mon Jul 10, 2023 6:08 am Post subject: Re: Weak spark to disappearing spark? |
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Steve, probably not the answer you want, but we had a 90 that was eating coils. Took about a day of constant driving. Van would get harder to start each fuel stop, till the last stop it would not restart. Swap in new coil and all was good till another long day. We were not able to duplicate the problem because of the time and distance. I did ohm out the new discarded coils and they tested to spec. I also tried to start the van with each one with no success. In this thread is what we did to try and pinpoint the problem. The van has since been cross country twice with no problems.
https://www.thesamba.com/vw/forum/viewtopic.php?t=509616
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Steve M.
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Joined: July 30, 2013
Posts: 6832
Location: Fort Lauderdale, Fl.
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| Posted: Mon Jul 10, 2023 10:10 am Post subject: Re: Weak spark to disappearing spark? |
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| MarkWard wrote: |
Steve, probably not the answer you want, but we had a 90 that was eating coils. Took about a day of constant driving. Van would get harder to start each fuel stop, till the last stop it would not restart. Swap in new coil and all was good till another long day. We were not able to duplicate the problem because of the time and distance. I did ohm out the new discarded coils and they tested to spec. I also tried to start the van with each one with no success. In this thread is what we did to try and pinpoint the problem. The van has since been cross country twice with no problems.
https://www.thesamba.com/vw/forum/viewtopic.php?t=509616 |
Thanks for this info, but definitely did not want to hear!!!
I checked the old coil I replaced 6 months ago and it also ohm'd out to spec.
Hope this is not going to be same problem as commuting Fort Lauderdale to WPB right now. Just did June going back/forth no problem. Now this...arghhh.
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Steve M.
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Joined: July 30, 2013
Posts: 6832
Location: Fort Lauderdale, Fl.
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| Posted: Fri Jul 14, 2023 4:38 am Post subject: Re: Weak spark to disappearing spark? |
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Well I got too busy at work so no time to r&r the ground terminals. I ordered the coil from GoWesty and 2 day shipping so that arrived yesterday. Installed it last night and "Wanda" fired right up.
I certainly hope it is not going to be the coil problem Mark has had problems with.
Just in case when I ordered the coil from GoWesty I ordered the cheapest coil from Rock Auto, the $16.95 one as a road spare in case this repeats.
The coil I took out had these numbers stamped on the bottom of the can, "2221001".
Now the coil I took out 6 months ago had the VW oem part number stamped on the bottom ending in the "349".
So did I have the wrong coil in there? The ECU has been woring fine as far as I can tell. I do not think the system did anything that could damage the coil to cause this problem, but maybe someone with more coil experience can say different?
The number "2221001" does not come up to being a coil part number anywhere I could find.
Time will tell.
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vanis13
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Joined: August 15, 2010
Posts: 3098
Location: ABQ NM USA.... Except when not
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| Posted: Fri Jul 14, 2023 5:41 am Post subject: Re: Weak spark to disappearing spark? |
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If it ends up eating coils, finding a seller with a good warranty (FCPEuro?. FLAPS?) buy two to have a spare one on hand (while the other is being warrantied) may be a good choice.
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MarkWard
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Joined: February 09, 2005
Posts: 17153
Location: Retired South Florida
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| Posted: Fri Jul 14, 2023 5:55 am Post subject: Re: Weak spark to disappearing spark? |
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Based on my experience with the 90 and my understanding and experience with the MSD 6AL if I still owned our syncro, I would upgrade the stock ignition to an MSD for reliability. Stock, all of the coil load is handled by the Digifant ECU. Overtime, that is asking a lot. The earlier digijet had an external ignition module/coil driver. It was mounted to a large aluminum heat sink. The digifant essentially has the ignition module incorporated into the fuel injection ECU. I haven’t torn one apart, but do to space restraints it’s likely not the same size heat sink the digijet system had.
My logic is, the MSD takes all the coil load off the stock ECU. The coil driver becomes a “signal” for the MSD to fire the MSD coil. That would have to reduce the load off the ECU coil driver.
If for some reason the MSD coil did fail, you can purchase them everywhere. Have never had an MSD ignition box or coil fail. The the customer van, since it started as a way to isolate the coil problem, I wired the MSD such that it could be disconnected and reconnected to stock. Owner was so pleased to have a reliable van, he fell back in love with it and the MSD remains. Happy ending.
Steve, hopefully it’s a fluke and we just happened across a bad batch of Bosch coils. I think I’d look for a good used original coil for backup.
Here is the kicker. When I worked in the dealer network. The mantra back then was coils never go bad. You need to look somewhere else.
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Steve M.
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Joined: July 30, 2013
Posts: 6832
Location: Fort Lauderdale, Fl.
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| Posted: Fri Jul 14, 2023 6:11 am Post subject: Re: Weak spark to disappearing spark? |
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| vanis13 wrote: |
| If it ends up eating coils, finding a seller with a good warranty (FCPEuro?. FLAPS?) buy two to have a spare one on hand (while the other is being warrantied) may be a good choice. |
I think the lifetime warranty from a FLAPS cannot be beat. However, the $16.95 coil from Rock Auto price makes up for the lifetime warranty to cover the time I budget to go the MSD coil driver like Mark suggests. Easy to buy 3 or 4 coils for the price of a "warrantied coil" and carrying one onboard as a spare is a better option then getting one from a FLAP's. The FLAPs more often then not are going to have hem on stock and if it's dead I can get it going in a half hour compared for waiting for one to come in on order.
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Steve M.
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Joined: July 30, 2013
Posts: 6832
Location: Fort Lauderdale, Fl.
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| Posted: Fri Jul 14, 2023 6:14 am Post subject: Re: Weak spark to disappearing spark? |
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| MarkWard wrote: |
Based on my experience with the 90 and my understanding and experience with the MSD 6AL if I still owned our syncro, I would upgrade the stock ignition to an MSD for reliability. Stock, all of the coil load is handled by the Digifant ECU. Overtime, that is asking a lot. The earlier digijet had an external ignition module/coil driver. It was mounted to a large aluminum heat sink. The digifant essentially has the ignition module incorporated into the fuel injection ECU. I haven’t torn one apart, but do to space restraints it’s likely not the same size heat sink the digijet system had.
My logic is, the MSD takes all the coil load off the stock ECU. The coil driver becomes a “signal” for the MSD to fire the MSD coil. That would have to reduce the load off the ECU coil driver.
If for some reason the MSD coil did fail, you can purchase them everywhere. Have never had an MSD ignition box or coil fail. The the customer van, since it started as a way to isolate the coil problem, I wired the MSD such that it could be disconnected and reconnected to stock. Owner was so pleased to have a reliable van, he fell back in love with it and the MSD remains. Happy ending.
Steve, hopefully it’s a fluke and we just happened across a bad batch of Bosch coils. I think I’d look for a good used original coil for backup.
Here is the kicker. When I worked in the dealer network. The mantra back then was coils never go bad. You need to look somewhere else. |
Looks like the MSD is the route to take then if this is an inherent problem for the reasons you mention.
My natural question has to be how has the coil been working okay for the past 30 yrs.? What's changed?
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MarkWard
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Posts: 17153
Location: Retired South Florida
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| Posted: Fri Jul 14, 2023 6:24 am Post subject: Re: Weak spark to disappearing spark? |
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Hey Steve, in the interim, install 2, 6mm studs in place of the mounting bolts. Then some wing nuts with lock washers. I recall you don’t have AC, but with a compressor and gravity, I find it a frustrating task. Hopefully it was just a Fluke. Excuse the pun.
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RawUmber
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Joined: June 23, 2019
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| Posted: Fri Jul 14, 2023 7:06 am Post subject: Re: Weak spark to disappearing spark? |
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If the problem has been narrowed down to the ECU, I'd try using a known good spare ECU rather than adding an external coil driver. This keeps it stock and doesn't introduce another point of failure.
As designed, the ECU can drive the coil on its own. If it's no longer up to the task, replace it with one that is. My two cents.
I'm not against solutions that work, but generally prefer seeing problems fixed at the source rather than kept in place and augmented with a crutch of sorts. YMMV. |
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DanHoug
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Joined: December 05, 2016
Posts: 4790
Location: Bemidji, MN
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| Posted: Fri Jul 14, 2023 8:43 am Post subject: Re: Weak spark to disappearing spark? |
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| MarkWard wrote: |
| When I worked in the dealer network. The mantra back then was coils never go bad. You need to look somewhere else. |
the broadcast world had a similar coil corollary mantra with old high power tube transmitters where everyone suspected the tube when things went wrong... "It's never the tube." and it usually wasn't.
not sooo many years ago, when dinosaurs walked the earth and points ruled the land, every hardware, farm, and auto parts store had orange and yellow blister packs of the "Wells" coil. back then, coils failed frequently. fast forward to the Cenozoic Digijet/Digifant Period that eliminated the points but still used a conventional coil, now emblazoned with red lightning bolt on a green sticker on the coil to indicate compatibility with electronic drivers of the ECU (Digifant) or the ignition amplifier (Digijet).
interesting bit of arcane knowledge (i'm looking at YOU, Duncan!)... old BMW airhead motorcycles '81 and on, used a very similar setup to the Digijet with the heatsink mounted ignition amplifier controlled by a Hall sensor. these BMW amplifiers/modules had a programmed routine to cut power to the ignition coil in 1.5 seconds if the key was on but engine not running to prevent overheating the coil. they used a Bosch lightning bolt coil with very low primary resistance that would charge quickly even at high rpm but could fry itself with extended dwell time.
a good thread on Vanagon coil failure
https://www.thesamba.com/vw/forum/viewtopic.php?t=581079&postorder=asc
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-dan
60% of what you find on the internet is wrong, including this post.
'87 Westy & '89 Westy both 2.1 4spd
Past projects can be found at--
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Steve M.
Samba Member
Joined: July 30, 2013
Posts: 6832
Location: Fort Lauderdale, Fl.
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| Posted: Fri Jul 14, 2023 8:49 am Post subject: Re: Weak spark to disappearing spark? |
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| MarkWard wrote: |
| Hey Steve, in the interim, install 2, 6mm studs in place of the mounting bolts. Then some wing nuts with lock washers. I recall you don’t have AC, but with a compressor and gravity, I find it a frustrating task. Hopefully it was just a Fluke. Excuse the pun. |
I just keep the bolt tightening the coil in the frame snug. It holds the coil, but I can twist it and slide it out.
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MarkWard
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Joined: February 09, 2005
Posts: 17153
Location: Retired South Florida
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| Posted: Fri Jul 14, 2023 8:55 am Post subject: Re: Weak spark to disappearing spark? |
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| RawUmber wrote: |
If the problem has been narrowed down to the ECU, I'd try using a known good spare ECU rather than adding an external coil driver. This keeps it stock and doesn't introduce another point of failure.
As designed, the ECU can drive the coil on its own. If it's no longer up to the task, replace it with one that is. My two cents.
I'm not against solutions that work, but generally prefer seeing problems fixed at the source rather than kept in place and augmented with a crutch of sorts. YMMV. |
Like those are falling out of the sky.  The intention was to determine if it was the ECU/coil combo that was taking out the ignition coils. As I said, we could not replicate the problem even on the chassis dyno. The MSD was on loan to see if he could drive from Florida to North Carolina without having to replace a coil. Two cross country trips with the MSD and no problems. Everything else the same. For the owner, he probably would not go back to stock. His interest is in reliabilty. So did we introduce points of failure or improve reliability? The owner would likely see it as improved. I still don't see how an ECU could take out a coil. More the opposite would make sense.
For the record, I carry a spare ECU for our TDI. If I owned a WBX, I'd also have a spare ECU.
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DanHoug
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Location: Bemidji, MN
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| Posted: Fri Jul 14, 2023 9:08 am Post subject: Re: Weak spark to disappearing spark? |
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| MarkWard wrote: |
| I still don't see how an ECU could take out a coil. More the opposite would make sense. |
if the dwell time becomes 'excessive', meaning too much on-time that is heating up the coil, it can cause coil damage. what i don't know is how dwell time is controlled by ECU + idle stabilizer control unit, how much dwell varies, and what the value that would cause damage is. DigiMatrix, you have any insight??
for people younger than some of my socks, points systems used a ballast resistor to limit current into the coil AND thru the points, extending the life of both. the ballast resistor was bypassed during cranking to give full voltage to the coil and when the starter was released, the current path resumed thru the ballast resistor. if the firewall mounted ballast resistor broke or burned out, no voltage to the coil EXCEPT when cranking. the symptom was the motor would run while it was being cranked but die as soon as the starter let off.
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-dan
60% of what you find on the internet is wrong, including this post.
'87 Westy & '89 Westy both 2.1 4spd
Past projects can be found at--
www.thefixitworkshop.com |
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khughes
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Joined: July 13, 2013
Posts: 747
Location: Phoenix AZ
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| Posted: Sat Jul 15, 2023 2:07 pm Post subject: Re: Weak spark to disappearing spark? |
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| DanHoug wrote: |
| MarkWard wrote: |
| I still don't see how an ECU could take out a coil. More the opposite would make sense. |
for people younger than some of my socks, points systems used a ballast resistor |
Yep, I remember seeing one while I was changing the oil in my air cleaner...
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DanHoug
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Posts: 4790
Location: Bemidji, MN
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| Posted: Sat Jul 15, 2023 4:13 pm Post subject: Re: Weak spark to disappearing spark? |
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| khughes wrote: |
| Yep, I remember seeing one while I was changing the oil in my air cleaner... |
ya ya. i hear you. but ballast resistors were used up thru the mid to late 70's, including VW. for further edumacation, this isn't a bad video, a few gaffs when he starts talking about voltage (coinciding with his stress swallowing--he's knows he's floundering!), but overall good info.
Link
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-dan
60% of what you find on the internet is wrong, including this post.
'87 Westy & '89 Westy both 2.1 4spd
Past projects can be found at--
www.thefixitworkshop.com |
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khughes
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Joined: July 13, 2013
Posts: 747
Location: Phoenix AZ
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| Posted: Sat Jul 15, 2023 5:05 pm Post subject: Re: Weak spark to disappearing spark? |
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Yeah, I started out in high school working on my uncle's truck fleet. Mostly Chrysler and International Harvester products! Lot of old IH 1-2 ton trucks with flathead V8s, a few flathead 6's (even now I still have a couple of tappet wrenches), and a lot of slant sixes in the Chislers. Gotta say, back in those days when 100k miles was pretty phenomenal life, those slant sixes would run forever if you halfway took care of them. Nothing uglier though than the sound of a chrysler starter...(unless it's cranking a Hemi)
Ballast resistors were basically gone by the time I got into 'them furren' cars
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