Hey everyone, First problem I've had so far. Installed new ngk plugs last weekend. The owners manual says gap the plugs to 0.039–0.043 inch, but everywhere I've personally looked says this car likes .045? I gapped them all to .45. I believe the plugs came pregapped at .38 or .39 can't remember exactly i do still have them in my garage though.

Tonight was the first night I drove the car since installing. The engine is misfiring so bad that it's undriveable. While driving on the highway the check engine light was flashing on and off. After about 10 minutes, the light stayed on. Pulled the code and it came up as P0302 cylinder 2 misfire detected.

I did the idle relearn, let it idle for 1 minute and then with a/c on for a minute and then drive. I can barely get past 2k rpm without is bucking so bad it actually throws me forward and backward in the seat. Ive never felt that before in my life.

My question is it possible that 1) I gapped the plugs to far apart? 2) Maybe the plugs are bad? 3) Just that one plug is bad?

I figure they shouldn't be bad since being brand new so I'm leaning towards gapped to high?

I believe the old plugs i took out where at .038 or .039 as well. Just wanted suggestions before i put the old plugs back in for now. They have about 37k miles on them and it looks to be the one piece design i believe. Car ran fine with those plugs. This was more of a "preventative maintenance" type of upgrade.

I attached a few photos of from the reader I just bought at a local walmart. This thing is pretty good for only $20. It just fuel trims at the time of the misfire and also MAF data at time of misfire. Not sure if those numbers look ok or not.

 

It could be any of the 3 to be honest.

I would suggest changing just just Cyl # 2 and seeing if the fault comes back on another cylinder. If you didn't change anything else it's got the be the plug(s). If it comes back try gapping to 0.39 instead. Good news is you can just go back to stock and it should all clear up.

 

I also installed a k&n cold air intake as well.

 

Any chance the CAI lets in too much air and the misfire is the result of a lean condition? Should the CAI have a tune with it?

 

Thank you for the reply. The american muscle showed this CAI as no tone required as it doesn't change the amount mass of air going through, just apparently how fast it sucks it throuhh rather than amount of air .

http://www.americanmuscle.com/kn-ser...-cai-10gt.html

Only reason I went with this instead of airaid is because it is carb certifies so I disn't have any issues with inspection. Maybe I thought wrong? Lol.

 

Car ran 100% fine before these mods.

 

Maybe too much anti-seize?

I did a sparkplug test several years ago on my last car (Dodge). I tried over $100 worth and 5 different brands of sparkplugs. After my test I realized the $1.98 factory replacements were the best overall sparkplug

 

Actually decided against anti seize from all the problems I hear could happen with it with fouled plugs or getting on the wrong part of the plug. Took my chances without it lol. Was thinking that I'm going to put the old ones back in and see if that makes any bit of difference. This weekend is suppose to be 45 heRe in ny, warm for winter, so taking her out for a good ride this weekend and hopefully get It running right before then.

this is crazy first mod I didn't since I bought it 2 months ago and already not working right lol

 

Or maybe I'll just do a quick coil swap with another one and see what happens, if it does it again I'll just change all the plugs back and hopefully that solves the issue for now until I figure out what to do with the new plugs.

still leaning towards gapped to far apart

 

So check this out, this is torqueD at 20ft lbs on each spark plug... how could this happen? And I'm guessing this could definitely cause misfires?

 

Yes, that could cause misfires.

 

The worst part is the code I got was cyl 2 misfire went. Took the coil off the plug on cylinder 2 and the porcelain was literally in pieces. I used 20ft lb of torque not even the recommended 25ft lbs. I wonder if the package was dropped on shipment and they had cracks in them that I didn't notice? I has to go to a local parts store and get a shop vac attachment to suck out all the porcelain pieces .

I dont understand how they all could craxk with using less of a torque than recommended

 

Might sound stupid, but did you use an actual spark plug socket with the rubber boot on the inside? Ive seen them crack when too much pressure was put on the top of the plug from the socket.

 

definitely doesn't sound stupid!! I have 2 spark plug sockets and neither of them fit I had to use a regular socket. Hmmm

 

A few things

1. I was told 15 ft.lbs. even though I know the specs say 25.
2. Check that torque wrench
3. I used a regular socket that was plenty deep
4. I wouldn't use NGK again even if it wasn't their fault. They a different one. I've used Autolite and Brisk in mine.
5. Use the anti seize. I know you were afraid of getting it on the electrode. Just be careful. A little goes a long was and put it on the threads only. I've never had a problem.
6. In all honesty I don't even know how this could happen. I've changed dozens if not hundreds of spark plugs and never a problem. I don't think you fracked them on the way in because you'd hear it I would think. I would just go with a different plug and chalk it up to a bad batch of plugs or a torque wrench that's somehow off.
7. Also put some of that die electric grease inside the coil boot when you put it in the plug. Just a bit. Not that this was the cause but just remember it's another step.

 

According to the Ford service manuals.. It lists 124 inch lb torque which = 10 ft lb torque for 2013 Mustang GT

At any rate, if you torqued your plugs to 20 ft lb torque.. This would explain the reason for the cracked plugs, as the specs call for 124 inch lb torque or 10 ft lbs torque following the conversion..

In the meantime, I've already went ahead and posted the torque specs from the Ford service manual below..

303-07B Engine Ignition — 5.0L (4V) 2013 Mustang
SPECIFICATIONS Procedure revision date: 01/24/2013
Item Specification
Spark plug 12405
Spark plug gap 1.25 - 1.35 mm (0.049 - 0.053 in)
Torque Specifications
Description Nm lb-in
Spark plugs 14 124
Copyright © 2014 Ford Motor Company

 

I busted a sparkplug once that looked like yours. It was caused by 'Me', when I was tightening the sparkplug. I had the socket on the sparkplug at a bad angle and it broke the porcelain. If this makes any sense

 

What caused the OP's cracked spark plugs was the result of being over torqued at 20 ft lbs.. According to the Ford service manual, the torque specs are 124 inch lbs torque which = 10 ft lbs. torque following the conversion..

 

I'd also invest in a sparkplug socket that fits properly.

 

Thank you all for the replies! I noticed that someone posted the specs from the 5.0 motor, I still have the 4.6l engine In my 2010, should I still only stick with 10ft lbs?