Spark Plug 3 misfire ONLY when engine is hot - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

Shayne70 · 03-30-2021, 01:18 AM

First off I changed all my spark plugs/wires and spark plug 3 coil as well twice.

My car runs fine when I first turn it on and it sounds perfect BUT when I drive it for over 10 miles or so spark plug 3 completely misses. I plugged my car in and it shows spark plug 3 completely misses. I'm practically running on 7 cylinders. I did delete the code.

I have a manual 2010, 80k miles SS.

Does anyone have any pointers or quick things to look at??? Thank you for the help. I am going to take it into the shop next week Wednesday to run some tests but I have no clue how much that is going to cost. T

Thank you for the help.

Greg P · 03-30-2021, 01:50 AM

Try swapping the coil to a different location and see if the misfire stays on #3 or moves to the new location.

xstuntman · 03-30-2021, 11:43 AM

Is the plug wet with fuel after its been running awhile?

Shayne70 · 03-31-2021, 01:59 AM

Quote:

Originally Posted by xstuntman

Is the plug wet with fuel after its been running awhile?

No the plug is dry and there is no build up of any kind.

Shayne70 · 03-31-2021, 02:00 AM

Quote:

Originally Posted by Greg P

Try swapping the coil to a different location and see if the misfire stays on #3 or moves to the new location.

I changed the coil twice and I am getting the same issue. This is the third coil I am using.

DB Cooper · 03-31-2021, 08:35 PM

With the engine cold, check the resistance across that injector and another one that's known good. Then warm the motor up till it starts missing, and check that injector again. If the resistance is changing a lot more than the good injector next to it, that points you in a direction. Or maybe try applying 5v across that injector while hot, and see if you can hear it click. If you try that, don't mass dump the whole fuel rail into the cylinder though. Just a quick touch. Injectors can act funny when hot, similar to the way coils can.

The fact that it's running nice when it's not warmed up strongly suggests it's not a valvetrain issue. And the fact that the plug isn't wet suggests it's probably not a spark issue. Another sign that would point to either fuel or spark would be whether the exhaust smells like raw fuel while it's missing. If not, you're probably getting spark, but no fuel to that cylinder.

xstuntman · 04-01-2021, 07:13 AM

I have never swapped injectors around myself so I don't know if its a pain but it would tell you something fairly quickly.
Either mechanical or electrical.

Camaro__ss · 04-01-2021, 07:05 PM

Compression test on the misfiring cylinder and one next to it...fingers crossed.

11-Camaro · 04-03-2021, 08:23 AM

Are you running a 2 step? Mine (Lingenfelter) went bad and I had this issue on several plugs. I replaced wires, plugs, coils and still had the issue. Could have saved a ton of money just unplugging it and plugging back directly to the coils to test. I finally did that and what do you know, my problems went away.

03-30-2021, 01:18 AM	#1
Shayne70 Drives: 2010 Black 2ss Chevy Camaro Join Date: Nov 2011 Location: Pearl City Posts: 341	Spark Plug 3 misfire ONLY when engine is hot First off I changed all my spark plugs/wires and spark plug 3 coil as well twice. My car runs fine when I first turn it on and it sounds perfect BUT when I drive it for over 10 miles or so spark plug 3 completely misses. I plugged my car in and it shows spark plug 3 completely misses. I'm practically running on 7 cylinders. I did delete the code. I have a manual 2010, 80k miles SS. Does anyone have any pointers or quick things to look at??? Thank you for the help. I am going to take it into the shop next week Wednesday to run some tests but I have no clue how much that is going to cost. T Thank you for the help.

04-01-2021, 07:13 AM	#7
xstuntman Drives: 2012 Victory Red LFX Join Date: Dec 2012 Location: west central Texas Posts: 1,310	I have never swapped injectors around myself so I don't know if its a pain but it would tell you something fairly quickly. Either mechanical or electrical. __________________ 2018 SS wheels, red Heritage grille, actual driving lights, ZL1 strut tower brace, GM Performance billet aluminum fuel door, front grille Bowtie delete, painted red rotors and calipers, 1/4 window American Flags, splash guards, AEM dry panel air filter.

04-03-2021, 08:23 AM	#9
11-Camaro Drives: 11 Camaro SS, Ninja 1000, Santa Fe Join Date: Sep 2020 Location: Dallas Posts: 49	Are you running a 2 step? Mine (Lingenfelter) went bad and I had this issue on several plugs. I replaced wires, plugs, coils and still had the issue. Could have saved a ton of money just unplugging it and plugging back directly to the coils to test. I finally did that and what do you know, my problems went away. __________________ 11 Camaro TT SS. 14 1LE motor, full coilover, CNC ported LSA heads, stainless valves, dual springs, Comp 224 cam, Melling oil pump, AGP Garrett GTX30r's, 1400cc injectors, full 3" Magnaflow, dual Walbro 450lph fuel pump, ZL1 6L90 trans, trans cooler, Circle-D 3600, 3.91:1 Eaton Truetrac, line lock, Lingenfelter 2 step. Current boost - e85 814 RWHP.

03-30-2021, 01:50 AM	#2
Greg P Drives: 2011 Camaro 2LT/RS Red Jewel Tint Join Date: Mar 2021 Location: BC Canada Posts: 12	Try swapping the coil to a different location and see if the misfire stays on #3 or moves to the new location.

03-30-2021, 11:43 AM	#3
xstuntman Drives: 2012 Victory Red LFX Join Date: Dec 2012 Location: west central Texas Posts: 1,310	Is the plug wet with fuel after its been running awhile? __________________ 2018 SS wheels, red Heritage grille, actual driving lights, ZL1 strut tower brace, GM Performance billet aluminum fuel door, front grille Bowtie delete, painted red rotors and calipers, 1/4 window American Flags, splash guards, AEM dry panel air filter.

03-31-2021, 08:35 PM	#6
DB Cooper Drives: 2010SS Join Date: Mar 2021 Location: Motor City Posts: 56	With the engine cold, check the resistance across that injector and another one that's known good. Then warm the motor up till it starts missing, and check that injector again. If the resistance is changing a lot more than the good injector next to it, that points you in a direction. Or maybe try applying 5v across that injector while hot, and see if you can hear it click. If you try that, don't mass dump the whole fuel rail into the cylinder though. Just a quick touch. Injectors can act funny when hot, similar to the way coils can. The fact that it's running nice when it's not warmed up strongly suggests it's not a valvetrain issue. And the fact that the plug isn't wet suggests it's probably not a spark issue. Another sign that would point to either fuel or spark would be whether the exhaust smells like raw fuel while it's missing. If not, you're probably getting spark, but no fuel to that cylinder.

04-01-2021, 07:05 PM	#8
Camaro__ss Drives: 2013 L99 Join Date: Jan 2019 Location: San Antonio TX Posts: 185	Compression test on the misfiring cylinder and one next to it...fingers crossed.