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spark plug gap question #4552049
10/23/17 01:34 PM
10/23/17 01:34 PM
Joined: Oct 2015
Posts: 207
co
NissanMaxima Offline OP
NissanMaxima  Offline OP
Joined: Oct 2015
Posts: 207
co
Hello all:

I need to change out the spark plugs on my Maxima with OEM recommended NGK platinum plugs and had two questions:

1. gap: my spec is 0.039" to 0.043". The NGK plus come pregapped at 0.044" and they tell me there will be no performance difference regapping to 0.040 (not sure why they chose this value). Honestly I would rather not mess with the NGK gap if this is true because I have regapped plugs in the past and it can be challenging. However, if I take the midpoint of 0.041", isn't 0.044, or 0.003" difference, a bit excessive? I have read that spark plug gap increases with use so why start out with a higher gap in the first place. To further try and educate myself, I then conducted a Google search looking for data on engine performance/efficiency as a function of spark plug gap and turned up nothing. It will be interesting to measure the gap of the plugs I remove however I don't know of course the exact value they were set to at the Nissan factory and maybe they didn't regap the OEM NGK plugs! In other words, I don't know the original gap value.
2. torque: my spec is 14-22 ft lbs. Why is there such a large range? I'm going to buy a good torque wrench. Should I just go for the midpoint value of 18 ft lbs?

Thanks

Re: spark plug gap question [Re: NissanMaxima] #4552057
10/23/17 01:41 PM
10/23/17 01:41 PM
Joined: Aug 2016
Posts: 661
New Jersey
THafeez Offline
THafeez  Offline
Joined: Aug 2016
Posts: 661
New Jersey
For the torques specs, I would say snug it up. Last time I used a torque wrench and went by oem standards, the plug was a bit loose and I was having rough starts. Tightened with 2 fingers after and all was good..

They give a range because a "snug fit" may vary from engine to engine. I realize that now because Toyota only gives one value for my car. Nissan probably gave a range because they knew some would need 19 while others would need 14. Snug it up and then use the torque wrench at 14, 15,16 and so on increments to see what your engine has if you so choose. Personally I wouldn't bother.

As for the gap, I would NOT try to regap it because you risk breaking the tip and the precious metals come off from the gapping tool as well. If you're really worried (I wouldn't be) only use feeler gauges. Don't use the cheap circle gap adjusters at autozone. I'd trust the NGK gap and leave it alone.

I remember the first time I did spark plugs I was worried about gaps and threading it wrong etc, it gets easier after that. It helps to put the plug on a small piece of hose and thread it backwards to seat it, then spin forward slowly. Good luck.


2004 Toyota Solara SE 2.4 2AZFE
182,000 miles
Castrol Magnatec Semi-Syn 5W30
Royal Purple 20-400 oversize 2nd run
Re: spark plug gap question [Re: THafeez] #4552060
10/23/17 01:44 PM
10/23/17 01:44 PM
Joined: Sep 2014
Posts: 1,487
Toronto Canada
WobblyElvis Offline
WobblyElvis  Offline
Joined: Sep 2014
Posts: 1,487
Toronto Canada
Originally Posted By: THafeez
For the torques specs, I would say snug it up. Last time I used a torque wrench and went by oem standards, the plug was a bit loose and I was having combustion problems. Tightened with 2 fingers after and all was good. As for the gap, I would NOT try to regap it because you risk breaking the tip and the precious metals come off from the gapping tool as well. If you're really worried (I wouldn't be) only use feeler gauges. Don't use the cheap circle gap adjusters at autozone. I'd trust the NGK gap and leave it alone.


+1

Re: spark plug gap question [Re: NissanMaxima] #4552095
10/23/17 02:21 PM
10/23/17 02:21 PM
Joined: Aug 2002
Posts: 14,556
Silicon Valley
PandaBear Offline
PandaBear  Offline
Joined: Aug 2002
Posts: 14,556
Silicon Valley
Plug gap has to consider electrode diameter as the overall calculation. If you are using fine wire plug you can go with a wider gap and still fire. Seriously, 0.004" is not going to make a difference.


"You keep asking questions PandaBear and you'll end up a vegetarian like my wife" - Camu Mahubah
Re: spark plug gap question [Re: NissanMaxima] #4552103
10/23/17 02:28 PM
10/23/17 02:28 PM
Joined: Mar 2007
Posts: 204
Minneapolis
03cvpi Offline
03cvpi  Offline
Joined: Mar 2007
Posts: 204
Minneapolis
I would re-gap to 0.040. Always to the mid or smaller end of the factory range. The larger the gap, the harder the coil has to work to fire the plug. Have seen many COP units fail because the gap increased 0.005 beyond range.

Electrode diameter has very little to do with air gap. Air gap is the critical measurement.

Have also seen a number of problems with VVT, plug misfire and poisoned cats because the air gap was beyond spec, usually by 0.008 to 0.012

Last edited by 03cvpi; 10/23/17 02:36 PM.
Re: spark plug gap question [Re: NissanMaxima] #4552122
10/23/17 02:51 PM
10/23/17 02:51 PM
Joined: Nov 2016
Posts: 1,283
WI
HoosierJeeper Offline
HoosierJeeper  Offline
Joined: Nov 2016
Posts: 1,283
WI
x2 on the above for gap and for those torque specs are for dry threads, I'd recommend using anti seize but that throws the torque specs off. I'd snug them by hand and then with the ratchet give 1/4 turn more.


15 Jeep KL Limited V6: Formula Shell 5W20
07 LR3 SE V8: Maxlife 5W30
05 Jeep KJ Limited: PHM 5W30
96 Jeep XJ Country: STP HM 5W30 (winter)
Re: spark plug gap question [Re: NissanMaxima] #4552159
10/23/17 03:35 PM
10/23/17 03:35 PM
Joined: Aug 2008
Posts: 21,194
ON, Canada eh?
StevieC Offline
StevieC  Offline
Joined: Aug 2008
Posts: 21,194
ON, Canada eh?
I would gap to 0.040 so as the electrode wears the gap will widen to the end of the acceptable range. If it's at the end of the acceptable range
to start with and the electrode wears you could put more stress on the coil and/or set a code on some ECU's if the coil is a bit weak, or worse cause a slight misfire condition.

As for the snugging. I like to put them in with barely any pressure on the ratchet and when it stops under this light force, I snug them a 1/4 - 1/2 a turn. (Don't over-tighten, no more than one hand's force at the bottom of the ratchet while turning this last little bit, so you have an idea of the pressure.) Just enough to compress the sealing washer slightly for a good seal.


Last edited by StevieC; 10/23/17 03:36 PM.

'18 Dodge Grand Caravan GT - AMSOIL SS 5w20
'06 Santa Fe - 535,000km AMSOIL SS 0w30 / ATF
Re: spark plug gap question [Re: NissanMaxima] #4552216
10/23/17 04:29 PM
10/23/17 04:29 PM
Joined: Mar 2008
Posts: 7,311
USA
slacktide_bitog Offline
slacktide_bitog  Offline
Joined: Mar 2008
Posts: 7,311
USA
What year Maxima? Is this a 4th gen Maxima? 95-99? I have a 96 I30 smile

I used 18 lb-ft when I changed them in my car, but I used Denso iridium. But I believe the stock NGK part number is 2647 aka PFR5G-11, where the 11 indicates 1.1 mm or .0433 in.

Just use them as-is with the prset gap and don;t worry about it again for a long time smile

At least we have cutouts int he intake to access the back plugs! Otherwise, I'd recommend iridium!

Re: spark plug gap question [Re: NissanMaxima] #4552225
10/23/17 04:33 PM
10/23/17 04:33 PM
Joined: Sep 2015
Posts: 1,588
USA
mk378 Offline
mk378  Offline
Joined: Sep 2015
Posts: 1,588
USA
Modern cars don't care much about the gap. It's typical to change out long-overdue spark plugs that have worn to twice the original gap but the engine was still running fine.

Gasket seal plugs are usually tightened by angle not by torque. Instructions often on the box.

Re: spark plug gap question [Re: NissanMaxima] #4552238
10/23/17 04:45 PM
10/23/17 04:45 PM
Joined: Jul 2003
Posts: 4,893
New Zealand
Silk Offline
Silk  Offline
Joined: Jul 2003
Posts: 4,893
New Zealand
The gap is 1.1mm, they just guess a number for imperial that is close enough. They are gapped correctly.


1987 BMW R65 - Aegis SAE30
2005 Nissan Expert - Gulf Western 10W-40
1996 Volvo T5 - Penrite HPR15 - 15W-60. Ryco syntec filter.
Re: spark plug gap question [Re: NissanMaxima] #4552242
10/23/17 04:48 PM
10/23/17 04:48 PM
Joined: May 2013
Posts: 2,160
Saskatchewan, Canada
Johnny2Bad Offline
Johnny2Bad  Offline
Joined: May 2013
Posts: 2,160
Saskatchewan, Canada
It's not recommended to re-gap platinum or iridium plugs. You risk cracking the electrode; both materials are very brittle as well as very hard.

0.44 is fine for any electronic ignition. Some are OK at 0.60" There is no real difference between 0.43 and 0.44", unless there is something seriously wrong with your ignition system and/or ECM. And I mean seriously wrong.

You should check the gap, though. Sometimes the wrong plug gap gets into the package. Return them for properly gapped units if that happens.


'57 FL Straight 50 wt
'90 Miata 1.8L w/Rotrex Supercharger [Mobil1 0W-40]
'96 Ram 1500 [3.7L Mobil1 0W-20 / 1L 15W-50]
'01 PT Cruiser [Mobil1 0W-40]
Re: spark plug gap question [Re: slacktide_bitog] #4552254
10/23/17 05:01 PM
10/23/17 05:01 PM
Joined: Oct 2015
Posts: 207
co
NissanMaxima Offline OP
NissanMaxima  Offline OP
Joined: Oct 2015
Posts: 207
co
Originally Posted By: slacktide_bitog
What year Maxima? Is this a 4th gen Maxima? 95-99? I have a 96 I30 smile


Yes! Fourth generation 95 in beautiful shape still - first time changing plugs in this car! You are also correct about the recommended plugs as the part number you gave is exactly the same as in my factory service manual. I did not realize the 11 in the part number indicated 1.1mm or 0.043".

-----
Seems the board is split between regapping and running as is. This is why I had hoped to see some articles or papers on true effect of increased gap on efficiency/performance. My sense was that if use increases gap and increased gap degrades efficiency/performance, why not start at the mid-range of the sped gap? But I've not heard or read anything to substantiate that. I'm hoping that the new plugs will restore some performance I used to have at lower elevations when the car was new but perhaps gap really doesn't matter (other than perhaps making the coils work harder as one member mentioned).

Re: spark plug gap question [Re: NissanMaxima] #4552304
10/23/17 05:33 PM
10/23/17 05:33 PM
Joined: Jan 2007
Posts: 17,501
Clovis, CA
Merkava_4 Offline
Merkava_4  Offline
Joined: Jan 2007
Posts: 17,501
Clovis, CA
Go by what the manufacturer of the car recommends.

Re: spark plug gap question [Re: NissanMaxima] #4552318
10/23/17 05:47 PM
10/23/17 05:47 PM
Joined: May 2010
Posts: 9,459
out there
spasm3 Offline
spasm3  Offline
Joined: May 2010
Posts: 9,459
out there
My olds calls for .060.


13 elantra 72k 5w30 QSUD
03 chevy avalanche 80k synpwr 5w30
17 mazda cx-5 7300 miles m1 0w30
Re: spark plug gap question [Re: NissanMaxima] #4552402
10/23/17 07:19 PM
10/23/17 07:19 PM
Joined: Nov 2004
Posts: 7,798
Texas
GMBoy Offline
GMBoy  Offline
Joined: Nov 2004
Posts: 7,798
Texas
I agree with everyone mentioning regap to .40. You are only touching the ground strap, not the fine delicate electrode so those saying you cannot gap these are incorrect. You must be careful for sure!

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