#2 Cylinder Eating Spark Plugs

07 Boss

Senior Member
Joined
Jan 25, 2009
Posts
3,876
Reaction score
1,002
Location
Sin City
Well not really eating them up but destroying them none the less. Not sure what is going on but this is the third plug I have had to replace prematurely. It's always been on the #2 cylinder. I generally pull my plugs once or twice a year just to look and clean them and swap them out before every racing season that I run. Occasionally I have found the spark plug a little loose and have read that this used to be an issue with the 2 valves but was unaware of any issues with the 3 valves. Anyways I have replaced the plug on this particular cylinder 3 times where the ceramic insulator has come loose. I pulled the plug and saw carbon soot on the ceramic insulator all the way up to where the coil boot sits. You can hold the nut and spin the top of it. So obviously I was not getting any or reduced compression and that was causing my stumble and miss. My question is why does it only happen with that cylinder and has anyone else experienced anything like this? I'm wondering if for some reason there might be a detonation issue causing unusually high cylinder pressure but there are no signs on the plug. I will invest in a borescope soon and see if I can see any tell tale signs of detonation. I literally have hundreds of tools and no borescope.

I will switch back to the $17 Brisk Racing plugs as I have always had the best success with these. The plug which I have replaced the last two times were Accel plugs. They are pretty new to the market but I thought I would give them a try because of the price and Accel was always pretty good to me in the past.
 

GlassTop09

Senior Member
Joined
May 24, 2019
Posts
1,153
Reaction score
537
Location
Farmington, NM
I've had this same issue to happen w\ my car (#3 & #4 cyl) earlier this year. My cause was indeed detonation but was due to excessive leaning of these 2 rear cylinders from uneven distribution of EVAP fumes\unmetered air set up by the EVAP porting of the FRPP IM I used to run then causing the PCM to excessively purge EVAP trying to determine from O2 sensor feedback (STFT's) if EVAP canister was empty causing increased unmetered air entry thus lean cylinders (in my case this affected all my plugs but only #3 & #4 blew thru the porcelains into the plug wells).

I know from the pictures of your engine that you don't have the PCV hooked up but do you still have the EVAP connected to inlet of your Whipple? If you do then you may want to check your EVAP system (especially the CPV to ensure that it is functioning properly & sealing off but also check all lines at the canister for leakage that can allow unmetered air to enter past the canister).
Depending on how all this routes thru the Whipple\intercooler & your O2 sensors report the feedback to the PCM, #2 cyl may be getting a majority of the excess unmetered air..........

Otherwise you may have a vacuum leak on #2 cylinder from injector O-ring failing, #2 intercooler to head O-ring leak or a faulty injector on #2 cyl leaning it out.........off the top of my head thinking here.

Hope this helps.
 

07 Boss

Senior Member
Joined
Jan 25, 2009
Posts
3,876
Reaction score
1,002
Location
Sin City
It just seems weird that it's just happening on the one cylinder. I will check into the things you mentioned but this really has me perplexed.
 

Juice

forum member
Joined
Aug 24, 2017
Posts
4,634
Reaction score
1,909
It just seems weird that it's just happening on the one cylinder. I will check into the things you mentioned but this really has me perplexed.
Just for shits and giggles, I would take out 2* global or WOT timing as a test. You probably wont be able to tell any loss of power.
 

GlassTop09

Senior Member
Joined
May 24, 2019
Posts
1,153
Reaction score
537
Location
Farmington, NM
It just seems weird that it's just happening on the one cylinder. I will check into the things you mentioned but this really has me perplexed.
I hear you, but when T\S'ing these more modern FI systems I've found you have to take everything into consideration & not make assumptions then go thru & eliminate everything that is not to find the cause that is.....IOW's test, don't guess. It also helps to learn how all of this actually works, both individually then as a collective to help to decipher some things. You also have to do the same w\ each part of the system as far as design goes to understand if there is a variation present that can set up a situation to affect only 1 cylinder in a more drastic way vs the others.

The following is stuff that I've thought of to consider just from reading your post.................

Since you've ran 3 different spark plugs thru the same cylinder & got the same result that IMHO rules out the spark plugs themselves as an issue.....ID's the cylinder. You've posted how the porcelain looks on #2 cyl but how do the rest look? (I don't know but you do) Are the rest all clean looking except #2? Or do all look kinda similar except #2 is much darker......if this is so then this may indicate a more common issue that is affecting #2 cyl the most but does affect the rest as well........

The issue w\ #2 cyl is heat related (heat transfers thru porcelain thru shell to cyl head).....more heat is being transferred thru #2 plug to cyl head vs the rest that is above its design tolerance range (or is not being transferred from shell to head vs the rest) to destroy this plug......how can this happen? Are you using anti-seize (is it copper or aluminum....HT aluminum would be better choice since the heads are aluminum to not induce galvanic corrosion between the plug shell & cyl head) on plug shell threads or are dry mounting them to cause heat transfer issues (you did mention it has come loose at times)? Is A\F mix being leaned thru this cyl vs the rest causing excessive detonation thus excessive heat.....now how can this occur on just 1 cyl.....or is this actually happening on all cylinders but just bad enough on #2 cyl to cause the plug to consistently fail here but not w\ the rest? Could this be indicating an air distribution issue within the intercooler to individual cylinders? Where in the system design can unmetered air enter by design? Is the EVAP system hooked up & being used......if so has this system been checked\tested recently\periodically for integrity? How does the SO PCM control this, how does it know when the canister is empty (unmetered air percentage increasing) & getting excessive? What can affect O2 sensor feedback fidelity to cause erratic fueling variations? How was the car being operated most when all this is happening? Mostly normal street driving or mostly at the strip under max loads (this will determine how much\often the PCM is operating EVAP purge cycles during engine operation)?

You do have LTH's installed........where in the collector is the O2 sensor mounted & which cylinders are closer to this sensor thru the collector merge to affect\sway the sensor exhaust sample volume\density from each cyl exhaust pulse to determine how the SO PCM will adjust the A\F mix for the next cyl in line on the same bank to fire (SO PCM can read individual cyl exhaust pulse using O2 sensor transport delay & engine timing but SO PCM is not programmed to individually adjust fueling per cyl....only by bank so depending on how the cyl exhaust sampled that is ahead of #2 cyl in the firing order in B1 will determine how much extra fuel thru STFT's (feedback that will be used to make fine corrections to fueling that are initially made from the MAF readings\calculations derived from ALL cylinders) #2 cyl will actually get (or how much extra fuel will get taken away) thus any unmetered air entry can skew this even further. LTFT's are an avg of all the STFT feedback readings\adjustments over time from individual cyls (that vary from the MAF calc's based on all 8 engine cyls drawing air thru the MAF sensor) in the bank that the O2 sensor serves so can correct for most of this but NOT ALL of it (the rest the PCM extrapolates or assumes if you prefer). You're running a FFE but you still use the rear O2 sensors.......can you determine by looking at the operational O2 sensor voltages of both B1S1\B1S2 to see if something jumps out to consider looking at B1S1's operation to ensure B1's O2 sensor feedback fidelity?

NB O2 sensors do not have a nerst cell (essentially an electronic air pump to ensure a consistent exhaust sample density from all cyls in a bank is contacting the sensor's element) like WB's do (1 of the main variables that make WB's so accurate vs NB's) thus NB's are affected by placement in the collector\pipe, the depth of the bung it's mounted in (determines how much of the shielding\element is exposed to internal exhaust flow) & the size (ID) of the pipe (determines how much exhaust flow velocity\density % at the pipe's inner surface area adjacent to sensor shielding.....not in the center of pipe......is entering the shielding to make contact w\ the element) so a lot of these seemingly small items can actually add up to this actually happening in tandem to cause this issue in a specific cyl......but how are you gonna know this?

You have indicated getting a borescope to check internal for any sign of physical damage to validate detonation as a cause of issue in #2 cyl.....also be good to look in the rest of the cyls to also look for indications of same to validate if symptom is widespread as well but especially in Bank 1 where potential fuel control issue is appearing due to plug inspection. Could follow up w\ a compression test\leakdown test to confirm\deny other symptoms as well as doing an injector pulse rate test on all injectors to see if #2 cyl injector is off compared to the rest......the more info gathered to eliminate what is not will get you to what is & get you there more accurately the 1st time....

Unless you test for all this to ensure that all is in spec & operating properly you're only assuming that all else is good. This is why it can be so perplexing to figure out..........you see the result of something going on but you can't readily (read quickly or easily here) figure out the cause........

This is a sample of how I use process analysis to tackle an issue such as this.....then run thru all of it testing\checking to eliminate all that is not to then find what it actually is.......but this is how I do it.

YMMV..............

Most in here would see all this as nitpicking or unnecessary......but then ask why would you? If you don't have a good enough handle of all the particular variables in\of your particular configuration & how well you understand the operations of each system separately then also as a collective, you can be open to misinterpretation of symptoms occurring before you & miss something in your diagnosis that can point you to the cause.......if you get into the habit of waiting on the PCM to flag a DTC to alert you of a situation & what to look at to point to a cause you can be too late to save your engine from catastrophic damage.

I posted due to me experiencing the exact same issue w\ a plug in my 4.6L as you describe (my case was 2 plugs.....in same bank & next to each other.......which were the farthest 2 cyls away from the offset EVAP port in the FPIM but this EVAP port also pointed directly into #1 & #2 cyl intake runners in the same bank & Bank 1 plugs were far away the worst affected from overheat due to detonation but all plugs showed symptoms of same but only #3 & #4 plugs showed blow thru into plug wells thus were leaned out far worse than the rest & I had actual Forscan datalog recordings of actual erratic STFT's\LTFT's along w\ EVAP operation in real time showing evidence of excessive unmetered air entry occurring thru EVAP system due to erratic O2 sensor feedback signal--STFT's--that caused the PCM to excessively purge EVAP--PCM uses STFT's rise above normal switching pattern to determine if EVAP canister is empty--to create the excess unmetered air entry due to PCM being unable to determine if canister was empty until it forced the STFT pattern out of "normal" enough to decipher the results by opening the CPV further making the situation worse).....then noticed the EVAP port route design on an OEM IM vs the FPIM to tie it all together (if I didn't know\understand how this all worked both individually & as a collective there's no way I could've picked all this out of a couple of datalogs). Then later on, based on all these earlier findings I got a hunch to test the 2 front O2 sensors voltage operation\heaters on a cold start from OL to CL transition & found that the O2 sensors I was using at the time (Ford F85F-9G444-BD.....made by BOSCH) were very poor in operation (didn't respond initially when heaters were hot enough for PCM to switch from OL to CL so PCM was flooding engine w\ fuel thinking it was lean until the sensors finally responded going rich then PCM pulled all excess fuel back to normal....which also had a hand in the plug damage found) but none of this threw a DTC--not even a pending DTC--as the sensors responded before the timer counted off (but I followed process & tested them anyway.......I had earlier swapped these in replacing my good NTK 22060, 22500 O2 sensors when running the cat CE ratio checks testing the Kooks Hi Flow race cats.....didn't see any change at the time so left them in.....so this 1 was on me) thus eliminated a future issue in the process as I also knew this had to be occurring whenever the engine went into DFSO as well (engine pumping air thru exhaust cooling the O2 senser elements already knowing the sensor heaters aren't that strong) thus causing this issue to happen temporarily once the PCM turned the injectors back on to return engine to operation....also affecting the plugs condition. The badly burned plugs were a symptom......the bad O2 sensors found AND the poor EVAP port routing design discovered in the FPIM creating erratic EVAP air distribution thru IM was the cause.....EVAP system itself was fine w\ all components tested\operating fine. All driving was normal engine operations where the PCM will perform EVAP operations (PCM disables EVAP during WOT) so I knew my issue wasn't due to high engine load% calc's but my tune's load% mapping has VCT limited to 20* max retard so avg engine dynamic cyl pressures will be higher to maintain better low speed TQ output thus the potential for detonation at low engine RPM's if something else was off\out of whack (this I also already knew beforehand so was factored into analysis) & thru all this I also discovered after the fact that this EVAP port issue in the FPIM was responsible for my Kooks Hi Flow cats to fail OBDII IM Readiness (had tested all this 1 yr earlier & knew that both cats initially passed but over time slowly failed but only B2 cat just barely failed w\ B1 cat passing both times indicating that something was off here--if cats are bad they should both set a pending DTC on 1st check after a KAM reset then set a permanent DTC on 2nd check.....std SO PCM operation for cat CE checks after a KAM reset straight out of FoMoCo's OBDII Theory & Operation Summary for 2009 vehicles......never happened during 2 successive tests......was using the same NTK 22060, 22500 O2 sensors I'm using now which tested good & were new then thus eliminated the O2 sensors back then as the plugs were brand new thus eliminated them as the EVAP system was also replaced & tested good back then which only left the FPIM's EVAP port routing design causing PCM to cause excessive EVAP purging from erratic STFT's which threw off cat CE calc's by flooding cats w\ excess unburned air--PCM uses STFT's in assessing exhaust O2 % going into cats to ensure proper CO & HC oxidation--that they couldn't use up thus got thru the substrate & hit the rear O2 sensors to slowly increase their switch counts relative to the front O2 sensors over time.....not because the cats were bad.....but I couldn't figure it out back then as I didn't have no other data to go off of at the time......the laptop & Forscan software came later on that fall) as I noted the cat CE ratios started improving immediately on each part replacement I made this spring (swapped out the IM's 1st, then swapped out the O2 sensors 2nd, then swapped out the plugs last w\ a set of used plugs--not new ones) thus validated the cause of that issue after the fact. So my new high dollar oversized MF #5461336 CARB-cert\VEI matching cats now get the benefit of all this testing\rectifying of these issues to further enhance their already excellent performance on a non-OEM equipped, cammed, FBO , tuned NA 4.6L engine to legally pass current EPA emissions stds if it needs to in the future......as currently configured to boot.

Sorry for all the wall of texts but I typed this to show that I practice what I preach thus is why I can say what I say w\ assurance as I also have the data on hand to back it up.

I know you'll find your culprit that is causing your issue on #2 cyl but you might need to go thru a process of elimination to unmask it.

Hope all this helps.
 
Last edited:

GlassTop09

Senior Member
Joined
May 24, 2019
Posts
1,153
Reaction score
537
Location
Farmington, NM
IMG_0487.JPG

This is for all those who falsely believe that a LTH collector design won't influence overall O2 sensor feedback fidelity to the PCM across a bank of cylinders when using a NB O2 sensor in it, please explain how the placement of the bung can't cause an imbalance when it can influence the exhaust % that can enter its shielding depending on the distance it is relative to the exhaust cyl primary porting into the LTH collector? My drawing isn't the best but it gets the point across.

This is the main reason why LTH's can have issues w\ cats passing emissions......especially when manuf's do the even dumber mistake & mount O2 sensor bung in collector ahead of the end of the merge spike.......the name brands aren't devoid of this mistake either.........I can prove this in spades as I have a set of Kooks LTH's that has this done to them from the factory........guess which side it is on.........Bank 1! Bank 2 LTH isn't much better but it is better than B1 is & I can show you how this is affecting LTFT's balance between both banks by the numbers. In reality the results are fine but if you didn't know this was a thing the numbers would drive some crazy trying to figure out why (as they did to me until I actually stopped long enough to actually pay attention to the LTH's collectors then ran a test by swapping known good O2 sensors across banks then seeing the results didn't follow the O2 sensor movements & change the numbers enough & all subsequent tests on the rest all came back good thus verified the issue w\ the O2 sensor bung placement in my Kooks LTH's collectors.

The only reason why I don't have to fix it is due to me finding\removing the other 2 variables in my car's system (the FPIM w\ its bad EVAP port routing & the poorly operating Ford F85F-9G444-BD O2 sensors) that made it far worse than it is on its own. All data shows that since fixing the 2 main culprits this issue isn't affecting the fidelity enough to matter now so don't need to fix it at this time (in Kooks defense there isn't enough room between the ball flange of LTH collector & end of merge spike to install an O2 sensor bung & stay out of the way of the flange......would actually have to install it in the 2 1\2" piping just aft of the flange on cat side to do it right......thus the 2 LTH collectors shouldn't have been used but they were......a QA\QC issue).

This is where WB's help to cover\mask stupid issues like this due to the nerst cell designed in them to constantly draw in exhaust sampling to even this out between primaries..........

NB's on the other hand.........you may need to look at this more closely than you may think you need to.......

With these modern FI control systems, attention to detail can be a life saver & can cut down on TS time..........

Something to think about.
 

07 Boss

Senior Member
Joined
Jan 25, 2009
Posts
3,876
Reaction score
1,002
Location
Sin City
I pull my plugs once or twice a year, more if I'm racing. It's an old school habit that I think more people should do. Reading plugs is a lost art in todays digital age. But I always examine and clean them up, or replace them. I've never seen anything unusual, no signs of detonation and a nice fine layer of light brown ash. The first plug was a brisk plug and the insulator on the inside cracked and slid down over the electrode and kept it from firing. The second and third time were with these Accel plugs and both times the upper outer insulator separated from the metal nut/body and there was evidence of combustion/soot on the top part of the plug. I'll try and find the plug and post up a pic. I tossed it in the garbage but I think I missed my toss and it might still be in the corner of my garage. Anyways this is over a period of 4-5 years. The brisk incident was discovered on install and I suspect the plug was defective when I put it in. The last time it happened was a couple years ago. When it happened this time I was cruising to work, uphill grade on the freeway running about 2700-2800 rpms. It just starts running shitty. No pop, no sign of anything going awry, just starts sputtering. I've been running the same set up for the last 75K miles. Tuned by Shelby Motorsports. The car has always run pretty darn good. I guess I'm going to have to start datalogging randomly hoping to see something. I'm going to have to buy some HP credits to hook up to the mustang. It's so random it's going to be hard to track down and honestly is not very high on my list. I'm only driving this car daily cause my vert has a balance/timing chain issue that I have yet to address.
 

Ekis

Junior Member
Joined
Jul 27, 2020
Posts
12
Reaction score
1
Check that the no 2 injector is working properly. It might be clogged.
 

Latest posts

Support us!

Support Us - Become A Supporting Member Today!

Click Here For Details

Sponsor Links

Banner image
Back
Top