What Will Happen With Wrong Spark Plug ?

[HTSS_TR]

Nothing so far !

Last weekend I changed speck plugs in my 2004 S2000, I have Bosch Platinum I bought last year for it, but then I found 4 NGK Platinum plugs BKR6EP-11 I have in my garage. I don't remember when I bought it and for which car, not for S2000 for sure.

I removed 1 original OEM plug which is NGK PFR7G-11S, the physical is identical to the BKR6EP-11 only the internal is difference (possible different heat range). Instead of using Bosch I tried the wrong NGK plug to see if the engine will behave any different.

After driving 45-50 miles the last few days on surface streets and highway, I could not detect any thing abnormal. The engine rev to 6-7k as normal, gas mileage is about the same, idle is as quiet as before.

Long term effect is unknown, but I will remove 1 or 2 plugs after 10-12k miles to check for the condition.

Any of you had used wrong spark plug(willingly on unwillingly) in the past and had severe negative effect on the engine ?

 

[jkhawaii]

some engines are very sensitive to aftermarket plugs. one vehicle I have seen caused the ignition coils to melt... yes, it sounds unbelievable but, it was true.

 

[ChrisW]

I think a possible way to see what effect it has on your engine would be to one, know what the original heat range is for your stock plugs, decode the NGK part number for it's design features and specs, then run a smog (or wide-band) with stock plugs then the 'incorrect' ones. I know that different temps in the combustion chamber can correlate to increased/decreased NOx (assuming the catalytic converter is at the same temperature and operating at the same efficiency on either plugs). I also looked a the application list for the BKR6EP-11 and see the only Honda application is for the 92-94 V6 Passport. Many Lexus/Toyota applications however.

 

[randomhero439]

My dad tried to tune up his ignition on his older Toyota. He bought eBay wires and cheap copper plugs. Ran like dog [censored], missed occasionally, took longer to start.

He replaced wires & plugs with OEM platinums and NGK wires. Runs perfect now.

 

[dparm]

Meh, just poor combustion. Car might run rough and throw check engine lights. Unless it ran for a long long time on the wrong plug, there was probably no harm done.

 

[JimPghPA]

Less MPG.

 

[GreeCguy]

I had a spark plug blow out of the cylinder head one time on a 1968 International pick up truck. That truck used the long threaded spark plugs. Cylinder number 3 fouled out and all I had in my junk box was the short threaded plugs. Figured it would hold. Truck cranked up and ran just fine. Made it about three miles down the road when it sounded like a shotgun went off under the hood follow by a loud "huffing/hissing" sound. Pulled over, raised the hood. The spark plug had blown out of the cylinder head and buried itself in the fender well.

 

[fdcg27]

If way too hot a plug is used, it'll suffer heat damage pretty quickly. Pieces may separate in the combustion chamber and will probably just leave through the exhaust valve but may cause damage.
If way too cold a plug is used, it'll foul.
If the reach is wrong, you could have interference with valves or piston or just poor combustion.
I suspect that an S2000 that isn't run really hard would be fine with a little hotter than spec plug.
I'd be inclined to stick with the recommended plug or equivalent with any engine.

 

[DuckRyder]

They are hotter by one range than specified.

See (Warning direct link to PDF) NGK Plug Numbers

 

[SwampSurvivor]

I went from Iridium to Platinum on my Focus. Definitely runs smoother.

I really don't think you can go wrong with a simple, basic plug - copper or platinum.

Some people claimed the Tauruses (3.0 Vulcan or Duratec) would have bad misfires with Bosch plugs. Never understood that as I see as sparkplug as a sparkplug as a sparkplug and the ignition coils were made by Bosch.

 

[dparm]

I never understood why people litter the Internet with SUBJECTIVE posts such as "oh Densos don't work well in Hondas."

For many years, NGKs were made under license by Bosch! So I agree: plugs are plugs. Get the right plug for your application, and it should not matter whose it is.

I am still a Denso Iridium fan because you can get the ultra-sharp 0.4mm tip (great for performance applications).

 

[exranger06]

I changed the spark plugs in the Explorer a few months ago. I discovered the shop that had changed them the last time used the wrong plugs in it. It caused some great confusion for me at the parts store. I ended up writing down the Motorcraft part number on the radiator support, went to the Ford dealer and got the OEM Motorcraft plugs.

Anyway, I never would have known that it had the wrong plugs in it. The truck always ran fine, and I didn't notice much difference with the correct Motorcraft plugs in. It still annoys me that the shop would use a blatantly wrong plug though. One more reason why I do everything myself now and avoid shops as much as possible.

 

[Cardenio327]

Originally Posted By: DuckRyder
They are hotter by one range than specified.

See (Warning direct link to PDF) NGK Plug Numbers


^^This^^

It's not a '49 Plymouth 217, changing heat ranges on modern engines is not a good idea.

Your S2000 has a high specific power output, well over the old benchmark of 1 horsepower per cubic inch, close to or exceeding the modern benchmark of 100 horsepower per liter. Running the engine under heavy load with too "hot" of a spark plug could cause pre-ignition, blistering or melting of plug insulators, melting of electrodes, cracked pistons, &c.

In Mexico there is a blatant disregard for plug heat ranges. The NGK BKR5E-11 is put in EVERYTHING that uses a 3/4" plug. Most people don't run their engines hard enough to do much damage, but everything that isn't a Tsuru or D/21 runs like dog[censored].

 

[HTSS_TR]

Thank you all for your inputs so far, my next question is: BKR6EP-11 is hotter by one range than PFR7G-11S according to NGK Plug Numbers posted by DuckRyder (Thanks).

Other than the heat range they are identical in every aspect such as thread dimensions, thread reach, resistor type , material construction, gap ...

My question is, if the heat range of BKR6EP-11 is hotter by one range than PFR7G-11S which is OEM, is it okay to leave it in for a short period of time (few thousands miles), or should I replace it as soon as possible this weekend ?

 

[Cardenio327]

If it were me I would change them as soon as possible.

Until you change them I wouldn't press the accelerator more than halfway down. I doubt the 6-7,000 rpm you mentioned would do any damage. Loading the engine is when damage can occur, more so when coolant & ambient temperatures are high.

 

[1 FMF]

Originally Posted By: jkhawaii
some engines are very sensitive to aftermarket plugs. one vehicle I have seen caused the ignition coils to melt... yes, it sounds unbelievable but, it was true.


what year, make, model vehicle? and what spark plug was used?

 

[JimPghPA]

Originally Posted By: dparm
I never understood why people litter the Internet with SUBJECTIVE posts such as "oh Densos don't work well in Hondas."

For many years, NGKs were made under license by Bosch! So I agree: plugs are plugs. Get the right plug for your application, and it should not matter whose it is.

I am still a Denso Iridium fan because you can get the ultra-sharp 0.4mm tip (great for performance applications).


Many people advise replacing the plug that comes with Chonda OPE.

 

[TFB1]

It'll probably be OK, but I'd be a lot more comfortable with a heat range colder than hotter... Problem could be spark knock but if the engine has knock sensors It'd likely never be a issue...

In a air cooled engine too hot(by two or three ranges) of plugs can cause overheating and engine damage, but can't say I've see same in a liquid cooled engine...

 

[kr_bitog]

Originally Posted By: Miller88
I went from Iridium to Platinum on my Focus. Definitely runs smoother.

I really don't think you can go wrong with a simple, basic plug - copper or platinum.

Some people claimed the Tauruses (3.0 Vulcan or Duratec) would have bad misfires with Bosch plugs. Never understood that as I see as sparkplug as a sparkplug as a sparkplug and the ignition coils were made by Bosch.

As I have written before, the first gen bosch platinum with tapllflushed electrode design may cause difficult start on engine with carb. As long the elctrode design, heat range and position relatively the same, it should not cause issue

 

[kr_bitog]

Originally Posted By: HTSS_TR
Thank you all for your inputs so far, my next question is: BKR6EP-11 is hotter by one range than PFR7G-11S according to NGK Plug Numbers posted by DuckRyder (Thanks).

Other than the heat range they are identical in every aspect such as thread dimensions, thread reach, resistor type , material construction, gap ...

My question is, if the heat range of BKR6EP-11 is hotter by one range than PFR7G-11S which is OEM, is it okay to leave it in for a short period of time (few thousands miles), or should I replace it as soon as possible this weekend ?

One range hotter typically is still tolerable, except the car already have overheating problem at the beginning. The pfr, ifr and bkr is interchangeable so no issue as long the gap is correct. BtW, why dont you use the champion 9201 you are selling?