Weak Spark/No Start - Source??
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From: Chgo Burbs
Weak Spark/No Start - Source??
1984 Corvette - Chasing a no start condition... History - Car started missing and chugging, could only get a max 35 Mph out of it. Made it home but now it won't start. Noted weak yellow spark during trouble shooting. Tested Volts to dizzy = 12.4 on Ignition, 9.9 when cranking. Replaced ignition module and tested coil resistance = in spec. What else should I be looking at? Can spark control module cause this issue? Any other suggestions? ECM?? Thanks.
Melting Slicks
Joined: May 2014
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From: New Port Richey FL
Control module's are for the most part a pass or fail not a weak spark thing, coils can test well on the low voltage tests but make you crazy on the road. Coils are not a very expensive on the Original Equipment level so a replacement cost is less painful than torment of is it good or not.
. Make sure if you do replace cap, coil and rotor that you bring over the ground bridge from old cap and replace center contact.
. Make sure if you do replace cap, coil and rotor that you bring over the ground bridge from old cap and replace center contact.
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Joined: May 2007
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From: Chgo Burbs
Control module's are for the most part a pass or fail not a weak spark thing, coils can test well on the low voltage tests but make you crazy on the road. Coils are not a very expensive on the Original Equipment level so a replacement cost is less painful than torment of is it good or not.
. Make sure if you do replace cap, coil and rotor that you bring over the ground bridge from old cap and replace center contact.
. Make sure if you do replace cap, coil and rotor that you bring over the ground bridge from old cap and replace center contact.
Pro
Joined: Aug 2020
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From: Liliha Bakery stuffing my face with coco puffs!
Control module's are for the most part a pass or fail not a weak spark thing, coils can test well on the low voltage tests but make you crazy on the road. Coils are not a very expensive on the Original Equipment level so a replacement cost is less painful than torment of is it good or not.
. Make sure if you do replace cap, coil and rotor that you bring over the ground bridge from old cap and replace center contact.
. Make sure if you do replace cap, coil and rotor that you bring over the ground bridge from old cap and replace center contact.
in my experience ICMs are all or nothing. Had a bad coil once that displayed rough running to the point the engine stalled. Pushed to the side of the road and restarted just fine. Drove a few miles and repeat. Finally dead about a mile from home...but as you mentioned coil is new. Plug wires???What does BobR have to say about that code 51? I don't think an ECM would have any influence on a weak spark.
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From: Chgo Burbs
in my experience ICMs are all or nothing. Had a bad coil once that displayed rough running to the point the engine stalled. Pushed to the side of the road and restarted just fine. Drove a few miles and repeat. Finally dead about a mile from home...but as you mentioned coil is new. Plug wires???What does BobR have to say about that code 51? I don't think an ECM would have any influence on a weak spark.
Last edited by capg; Oct 17, 2021 at 11:39 AM. Reason: grammer
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From: Chgo Burbs
Melting Slicks
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From: New Port Richey FL
A common forgotten part that is left behind in the old cap is the ground bridge a stamped steel piece sits under the coil. In many cases people will open a pile of boxes to replace the cap & coil a lot of the time the bridge is not included or is just cheap tin that you look and say we're the Hell does go, the GM on is better in most cases. The contact most of the time the contact that do come with the cap are cheap.
Last edited by s carter; Oct 17, 2021 at 02:34 PM.
Pro
Joined: Aug 2020
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From: Liliha Bakery stuffing my face with coco puffs!
I'm a visual kinda guy... Would it even run with that piece missing???
https://www.corvetteforum.com/forums...stributor.html
https://www.corvetteforum.com/forums...stributor.html
Last edited by stew86MCSS396; Oct 17, 2021 at 04:50 PM.
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Melting Slicks
Joined: May 2014
Posts: 2,894
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From: New Port Richey FL
I'm a visual kinda guy... Would it even run with that piece missing???
https://www.corvetteforum.com/forums...stributor.html
https://www.corvetteforum.com/forums...stributor.html
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Joined: May 2007
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From: Chgo Burbs
New DUI coil, cap, rotor, and ignition module from Summit did the trick... had it in a few days - fast. So, lessons learned??? Don't trust cheap chit ignition modules OR coils that test within spec. Ha. Nothing like the shotgun approach to fixing things - at least I saved shop fees!
Instructor
Joined: Sep 2007
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From: Apollo Beach. Fla
New DUI coil, cap, rotor, and ignition module from Summit did the trick... had it in a few days - fast. So, lessons learned??? Don't trust cheap chit ignition modules OR coils that test within spec. Ha. Nothing like the shotgun approach to fixing things - at least I saved shop fees!
Melting Slicks
Joined: Jun 2011
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From: Leland , North Carolina