misfire conundrum
Thread Starter
Team Owner
Joined: Oct 2004
Posts: 81,241
Likes: 3,062
From: altered state
St. Jude Donor '05
misfire conundrum
sbc msd
Symptoms were lazy idle, reduced power, hard restarts slight studdering around 2-3k as if there was too much timing, bucked some at low rpm
Replaced
Coil
Wires
Cap
Rotor
Plugs have 10 mi but show the result of not enough spark, hate to change again less I have to.
If the magnetic pickup/miodule was bad it would just quit?
Same with the box?
Hopefully sort this out or throw it out for an HEI.
Anyone run into this? Always ran clean as a whisltle prior to, less than 100 mi on everything (engine too)battery new
Symptoms were lazy idle, reduced power, hard restarts slight studdering around 2-3k as if there was too much timing, bucked some at low rpm
Replaced
Coil
Wires
Cap
Rotor
Plugs have 10 mi but show the result of not enough spark, hate to change again less I have to.
If the magnetic pickup/miodule was bad it would just quit?
Same with the box?
Hopefully sort this out or throw it out for an HEI.
Anyone run into this? Always ran clean as a whisltle prior to, less than 100 mi on everything (engine too)battery new
Last edited by cv67; Aug 24, 2019 at 04:25 PM.
Thread Starter
Team Owner
Joined: Oct 2004
Posts: 81,241
Likes: 3,062
From: altered state
St. Jude Donor '05
Its discontinued......8 yrs ago bought a summit brand MSD type system. At that time it was made my msd for them...no pn
Their replacements are now being made in a sweat shop in china..all parts, wiring is identical
Ive never heard the rev limiter come on starting to wonder if this things no good.
Go Pro is broken sure a clip would help
Their replacements are now being made in a sweat shop in china..all parts, wiring is identical
Ive never heard the rev limiter come on starting to wonder if this things no good.
Go Pro is broken sure a clip would help
Thread Starter
Team Owner
Joined: Oct 2004
Posts: 81,241
Likes: 3,062
From: altered state
St. Jude Donor '05
leaning that direction the only reason I bought it is with 82 deg overlap was concerned about plugs loading up.
Simply dont trust these things seen too man fail over the years. Think all the rev limiters, 2 steps etc are for track rats/kids.
Dist had to be torn apart brand new and rebuilt as the bushings werent right was never happy with it.
Throwing plugs in think if that doesnt solve it I will make the switch to HEI keep it simple. Plus I can actually read the timing light lol
Jackson what do you recommend for a module? The engine sees as much as 7500 on occasion. Coil?
Simply dont trust these things seen too man fail over the years. Think all the rev limiters, 2 steps etc are for track rats/kids.
Dist had to be torn apart brand new and rebuilt as the bushings werent right was never happy with it.
Throwing plugs in think if that doesnt solve it I will make the switch to HEI keep it simple. Plus I can actually read the timing light lol
Jackson what do you recommend for a module? The engine sees as much as 7500 on occasion. Coil?
Last edited by cv67; Aug 25, 2019 at 01:08 PM.
Thread Starter
Team Owner
Joined: Oct 2004
Posts: 81,241
Likes: 3,062
From: altered state
St. Jude Donor '05
Youre referring to the HEI Jackson? For some reason I recall reading (yeah I know...) the GM module wouldnt handle high rpm if it does thats good news.
Last edited by cv67; Aug 25, 2019 at 09:04 PM.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
2027 Corvette vs The World: Every C8 vs Its Closest Competitor
Joe Kucinski
10 Most Common Corvette Problems of the Last 20 Years!
Joe Kucinski
5 MOST and 5 LEAST Popular Corvette Model Years in History!
Joe Kucinski
2027 Corvette Buyer's Guide: Everything You Need to Know!
Joe Kucinski
10 Things C8 Corvette Owners Hate (But Won't Tell You)
Joe Kucinski
10 Best Corvettes Coming to Barrett-Jackson Palm Beach 2026!
Brett Foote
Every Corvette Grand Sport Explained! (C2, C4, C6, C7, & C8)
Joe Kucinski
Thread Starter
Team Owner
Joined: Oct 2004
Posts: 81,241
Likes: 3,062
From: altered state
St. Jude Donor '05
threw plugs at it, retimed, misfire is still there, acts like it has too much timing
Think I have a fd distributor gear.;btw those nubs on the end of msd wires want to fry, going back to summit brand or parts store wires they run no different and fit better.
Think I have a fd distributor gear.;btw those nubs on the end of msd wires want to fry, going back to summit brand or parts store wires they run no different and fit better.
Last edited by cv67; Sep 8, 2019 at 01:46 PM.
Is my vette stock?? HAHA
Joined: Oct 2015
Posts: 20,070
Likes: 9,203
From: Im not allowed to tell you
2020 C3 of the Year Finalist - Modified
2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
2016 C3 of Year Finalist
If its a Summit part, call them and ask if there is a replacement available. I had a bad gauge from them and they gave me credit towards an autometer guage. Maybe they will help you out towards a real MSD. MSD had a troubleshooting flow chart for the new digital ones
Dr. Detroit
Joined: Mar 2012
Posts: 10,091
Likes: 4,016
From: New Braunfels Texas
I have said this before but inspect each spark plug for a cracked ceramic.......this is VERY hard to see and can have a person chasing their tail to no end. It would have the exact symptoms you describe.
Even new plugs can be broken in the box.......I ran into this on my 383 ElCamino.....it was a mule and had an HEI.....it was hard as hell to start and ran like **** when it did......I OHM'd wires....checked the plugs (Electrode) and the cap was off like 5 times making sure the button wasn't eroded. One day standing there with it running I could hear some ticking....I was looking around and a VERY small zap was jumping to the header from the plug. I shut it off and pulled that plug.....inspected the wire-OK, but held the plug up close and there was a hairline crack in the ceramic. Threw a plug in it and it was like different car.
Jebby
Even new plugs can be broken in the box.......I ran into this on my 383 ElCamino.....it was a mule and had an HEI.....it was hard as hell to start and ran like **** when it did......I OHM'd wires....checked the plugs (Electrode) and the cap was off like 5 times making sure the button wasn't eroded. One day standing there with it running I could hear some ticking....I was looking around and a VERY small zap was jumping to the header from the plug. I shut it off and pulled that plug.....inspected the wire-OK, but held the plug up close and there was a hairline crack in the ceramic. Threw a plug in it and it was like different car.
Jebby
Thread Starter
Team Owner
Joined: Oct 2004
Posts: 81,241
Likes: 3,062
From: altered state
St. Jude Donor '05
Replaced them in case one was cracked runs the same
Summit wont stand behind this....even though it has maybe 60 mi the system is 8 yrs old. Nice...didnt expect them to
Ck distributor gear is next, this has had lots of milling so ate 1 right off the bat (bronze big mistake)
Dont hear abnormal valvetrain noise so for now ruling out a bad solid lifter (roller)
Overlooked the fact the coil wire has never been replaced.
Leave ck the gear til last as the shaft always leans to one side making reinstall a royal pain. With 10 blown discs and 6 tumors on my spine leaning over a hood isnt something easily done.
Summit wont stand behind this....even though it has maybe 60 mi the system is 8 yrs old. Nice...didnt expect them to
Ck distributor gear is next, this has had lots of milling so ate 1 right off the bat (bronze big mistake)
Dont hear abnormal valvetrain noise so for now ruling out a bad solid lifter (roller)
Overlooked the fact the coil wire has never been replaced.
Leave ck the gear til last as the shaft always leans to one side making reinstall a royal pain. With 10 blown discs and 6 tumors on my spine leaning over a hood isnt something easily done.
Last edited by cv67; Sep 11, 2019 at 04:10 PM.
Thread Starter
Team Owner
Joined: Oct 2004
Posts: 81,241
Likes: 3,062
From: altered state
St. Jude Donor '05
Autolite 3924s...plugs I took out or ones I just put in? Runs same
Gapped at .035
Wires I had were some msd's Ive had forever but thought maybe they got damaged being stuffed in boxes so went to Napa spent 28 bux and got their "best" 8mm set. Found over time theres no difference between fancy stuff and good parts store wires but worst case Im not out much $
Gapped at .035
Wires I had were some msd's Ive had forever but thought maybe they got damaged being stuffed in boxes so went to Napa spent 28 bux and got their "best" 8mm set. Found over time theres no difference between fancy stuff and good parts store wires but worst case Im not out much $
Last edited by cv67; Sep 12, 2019 at 10:43 AM.