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Misfires after spark plug change!?

rkar

Registered Member
103
41
28
So 3.3T stock ecu no jb4 or any tune, but I do have 5346 Denso's installed on a stock ecu. Had them installed before hand, before I purchase a jb4. Had them on for about 600 miles or so (the new plugs) gapped to around .020 is what I was told by the shop. I just recently started to get a miss fire at WOT when I step on the gas off the light, car cuts power throws a CEL for a brief second then power comes back on. Anyone else experience this problem with upgraded plugs on a stock car? Just curious, probably just a bad plug. Gonna take the car back to get it checked out again. Car was running great though with the new plugs, felt way more responsive than stock.
 

Kraig Wilkinson

Registered Member
1,472
544
113
New Jersey now live in South Dakota
Genesis Model Type
2G Genesis Sedan (2015-2016)
So 3.3T stock ecu no jb4 or any tune, but I do have 5346 Denso's installed on a stock ecu. Had them installed before hand, before I purchase a jb4. Had them on for about 600 miles or so (the new plugs) gapped to around .020 is what I was told by the shop. I just recently started to get a miss fire at WOT when I step on the gas off the light, car cuts power throws a CEL for a brief second then power comes back on. Anyone else experience this problem with upgraded plugs on a stock car? Just curious, probably just a bad plug. Gonna take the car back to get it checked out again. Car was running great though with the new plugs, felt way more responsive than stock.
It could be a bad plug? 20thousands gap? Wow that is not much at all, I would think it would be a little bigger of a gap? I dont know much about them 3.3 engines ,but have been around engines my whole life and never heard of a low gap.
 
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Kraig Wilkinson

Registered Member
1,472
544
113
New Jersey now live in South Dakota
Genesis Model Type
2G Genesis Sedan (2015-2016)
It could be a bad plug? 20thousands gap? Wow that is not much at all, I would think it would be a little bigger of a gap? I dont know much about them 3.3 engines ,but have been around engines my whole life and never heard of a low gap.
I hope it is something stupid and you get it right! Good luck,keep us posted if you would . Thanks!
 

Toddasaurus

REEEEEEEEEEEEEEEE!!!!!
3,299
4,471
113
Genesis Model Type
Genesis G70
Unless you changed something else, it's probably those plugs. There have been (unconfirmed) reports of some phony Denso's being sold around various retailers. Either way, one or more of those plugs are bad, the coil pack(s) may have come disconnected, your plugs' gap is simply too small, and/or the plugs are just too cold for stock boost/timing/AFR's and have fouled up already.

Start your troubleshooting by pulling the Denso's and take a close look at the electrodes and ground straps. Make sure those coil packs are in one piece (the stems can separate) and firmly clicked onto the plugs.
 

rkar

Registered Member
103
41
28
Unless you changed something else, it's probably those plugs. There have been (unconfirmed) reports of some phony Denso's being sold around various retailers. Either way, one or more of those plugs are bad, the coil pack(s) may have come disconnected, your plugs' gap is simply too small, and/or the plugs are just too cold for stock boost/timing/AFR's and have fouled up already.

Start your troubleshooting by pulling the Denso's and take a close look at the electrodes and ground straps. Make sure those coil packs are in one piece (the stems can separate) and firmly clicked onto the plugs.
Awesome thanks guys i'll keep you guys posted.
 

rkar

Registered Member
103
41
28
2 ranges colder without a tune or a piggyback is asking for trouble! Plus such a small gap would require high boost which you're not giving it!
Could possibly be. We shall see..
______________________________
 

joschneider

G70-less
SUSTAINING MEMBER
1,686
2,008
113
Las Vegas, NV
So I thought I was having miss fires... But I wasn't. It was my traction control coming on and cutting power. This is what happens when you haven't had a new car in 11 plus years lol. Cars running great. No codes or miss fires at all. Now I drive with traction control off.:rolleyes:
you said you saw a CEL come on when this happened? was it actually the TC light flashing at you then?
 

Toddasaurus

REEEEEEEEEEEEEEEE!!!!!
3,299
4,471
113
Genesis Model Type
Genesis G70
Nice! I'm glad to hear a good resolution to this.
 

Toddasaurus

REEEEEEEEEEEEEEEE!!!!!
3,299
4,471
113
Genesis Model Type
Genesis G70
Was the misfiring occurring about half the throttle?


If you take a look at post #10, you'll see that he wasn't having any misfires; rather, his TC was enabled and cutting power.
 

Toddasaurus

REEEEEEEEEEEEEEEE!!!!!
3,299
4,471
113
Genesis Model Type
Genesis G70
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