Changed Spark Plugs now misfire on all cylinders - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

EJSS · 09-23-2021, 11:57 PM

Im left sort of speechless on this one...

I changed all of my spark plugs last night on my L99, went with the same exact plugs that were already in, the GM 41-110 Iridiums. Same spark plugs, same gap. Misfires on all cylinders, knock retard going crazy... I can hear an audible knocking/tapping sound on my way home from work.

So tonight, I just pulled all 8 of the new plugs out and replaced the old plugs back in. No more misfires, everything is back to normal. WTF? How does the car know the difference between the new ones and old ones?? Why does it like the old ones more? Same exact plugs with the SAME DAMN GAP. C'mon man!

102SS · 09-24-2021, 05:00 AM

Maybe your new plugs were dropped or handled roughly before you bought them.

I put Denso Iridium's in mine and everything is fine.

Y88 TA · 09-24-2021, 06:03 AM

Where did you buy your new plugs from? Could be cheap knock offs from ebay or amazon.

hunter1660 · 09-24-2021, 07:11 AM

Just because a part is new doesn’t mean it’s good

EJSS · 09-24-2021, 07:33 AM

Nevermind problem came back lol. Spoke too soon

Aqua Blue RS/SS · 09-24-2021, 07:34 AM

Quote:

Originally Posted by Y88 TA

Where did you buy your new plugs from? Could be cheap knock offs from ebay or amazon.

This!!! There’s a flood of Chinese knock offs on the market, they can be a little hard to spot from the real ones.

Rock-It Man · 09-24-2021, 07:37 AM

Quote:

Originally Posted by EJSS

Nevermind problem came back lol. Spoke too soon

Now that you have replicated the problem with the old plugs, it's time to consider whether the wires are OK. It's not hard to damage them if you take them off roughly.

1JEWLDSSRS · 09-24-2021, 09:05 AM

Quote:

Originally Posted by Rock-It Man

Now that you have replicated the problem with the old plugs, it's time to consider whether the wires are OK. It's not hard to damage them if you take them off roughly.

^^^ this, I have seen where the connectors inside the boot come apart and not make a good connection anymore and cause problems. Check the plug wires.

Bigdumogre · 09-24-2021, 01:33 PM

If it has factory wires replace them. Mine where original last year and many where dry rotted. By removing them you might of compromised there integrity of them and now they are giving you problems.

EJSS · 09-25-2021, 12:08 AM

Thanks everyone, I will be replacing the wires ASAP and I'll do an update once it's done.

AlanRubin · 09-25-2021, 01:38 AM

As the plugs age, and the gaps widen with age, the ECU adjusts. When you replace
the plugs, the timing will be off slightly, the ECU needs reset. The "learning"
is gradual as they age, then you jump down to a gap that's original, which will be
smaller than the old plugs. IT happens...

Also, yeah, the connector in the boots can pull out of the crimp... Just had that
happen on my Mustang, but only two of them.

FlashCamaroSS · 09-25-2021, 03:01 AM

Check the flow of charge with electric tester. might have a bad wire or 2.

HyperV117 · 09-27-2021, 11:46 AM

I had this happen once. Turns out I didn't push the plug cables all the way in.

09-23-2021, 11:57 PM	#1
EJSS Drives: 2010 Camaro SS L99 Join Date: May 2019 Location: New Orleans Posts: 119	Changed Spark Plugs now misfire on all cylinders Im left sort of speechless on this one... I changed all of my spark plugs last night on my L99, went with the same exact plugs that were already in, the GM 41-110 Iridiums. Same spark plugs, same gap. Misfires on all cylinders, knock retard going crazy... I can hear an audible knocking/tapping sound on my way home from work. So tonight, I just pulled all 8 of the new plugs out and replaced the old plugs back in. No more misfires, everything is back to normal. WTF? How does the car know the difference between the new ones and old ones?? Why does it like the old ones more? Same exact plugs with the SAME DAMN GAP. C'mon man!

09-24-2021, 05:00 AM	#2
102SS waiting at the tree Drives: SIM 2010 2SS/RS A6 Join Date: Apr 2013 Location: Niagara Falls Posts: 3,131	Maybe your new plugs were dropped or handled roughly before you bought them. I put Denso Iridium's in mine and everything is fine. __________________ 2010 2SS/RS A6 ZL1 Rims 60ft 2.03 13.08 at 107.82 (4/28) 2009 Pontiac G8 3.6L the DD

09-24-2021, 07:11 AM	#4
hunter1660 Drives: 2011ss/rs camaro Join Date: Sep 2011 Location: florida Posts: 1,261	Just because a part is new doesn’t mean it’s good __________________ . OBX LTH,Rotofab,Magnuson Heartbeat.AEM wideband, HP Tuners

09-24-2021, 01:33 PM	#9
Bigdumogre Drives: 2012 Camaro SS Join Date: Dec 2019 Location: New York Posts: 1,434	If it has factory wires replace them. Mine where original last year and many where dry rotted. By removing them you might of compromised there integrity of them and now they are giving you problems. __________________ 2012 Camaro 2SS/RS - CSP Custom Cam 232/240 .615/.615 113 +3, Texas speed CNC heads, FTI billet triple disc converter, K&N cai, Katech ported TB, GPI Ported/rod modded manifold, Texas speed 1 7/8 headers, HFC, Flowmaster 2 chambers with x pipe, Mishimoto CC, MSD wires, Roto fab washer relocation, tru cool 40k trans cooler, apex scoop, Pedders extreme coil overs and much more!!

09-27-2021, 11:46 AM	#13
HyperV117 Drives: 2010 Camaro 1SS Join Date: Nov 2015 Location: CA Posts: 358	I had this happen once. Turns out I didn't push the plug cables all the way in. __________________

09-24-2021, 06:03 AM	#3
Y88 TA Drives: 2010 RJT 2SS 6 Manual, 1978 Y88 TA Join Date: Mar 2021 Location: Regina Sk. Posts: 55 View My Garage	Where did you buy your new plugs from? Could be cheap knock offs from ebay or amazon.

09-24-2021, 07:33 AM	#5
EJSS Drives: 2010 Camaro SS L99 Join Date: May 2019 Location: New Orleans Posts: 119	Nevermind problem came back lol. Spoke too soon

09-25-2021, 12:08 AM	#10
EJSS Drives: 2010 Camaro SS L99 Join Date: May 2019 Location: New Orleans Posts: 119	Thanks everyone, I will be replacing the wires ASAP and I'll do an update once it's done.

09-25-2021, 01:38 AM	#11
AlanRubin Banned Drives: 2010 LS Join Date: Feb 2021 Location: Pgh Posts: 411	As the plugs age, and the gaps widen with age, the ECU adjusts. When you replace the plugs, the timing will be off slightly, the ECU needs reset. The "learning" is gradual as they age, then you jump down to a gap that's original, which will be smaller than the old plugs. IT happens... Also, yeah, the connector in the boots can pull out of the crimp... Just had that happen on my Mustang, but only two of them.

09-25-2021, 03:01 AM	#12
FlashCamaroSS Drives: 2010 Camaro SS Join Date: Oct 2019 Location: Alabama Posts: 1 View My Garage	Check the flow of charge with electric tester. might have a bad wire or 2.