Spark Plug Gap - Nissan Forums : Nissan Forum
 
LinkBack Thread Tools Display Modes
post #1 of 11 Old 12-11-2017, 01:55 PM Thread Starter
Registered User
 
Join Date: Dec 2017
Posts: 6
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Thanks: 0
Thanked 0 Times in 0 Posts
iTrader: 0 reviews
(Thread Starter)
Cool Spark Plug Gap

I recently bought original spark plugs (NGK) for my 2012 altima and they were supposed to be gapped at the factory at 0.044. However, when I installed them I noticed that the car was rough idling and the engine was noisier than normal. I decided to check the gap and they were actually gapped at 0.041-42. I corrected the gap to 0.044 and the engine is running better. I then decided to run a little experiment and set the gap at 0.050 and the engine is even quieter.

My question: would increasing the gap even more (like to 0.055) have any detrimental effects on the car (ignition system, coils, etc.)?

Thanks.

dannnyjos is offline  
Sponsored Links
Advertisement
 
post #2 of 11 Old 12-11-2017, 03:51 PM
09 Altima 3.5SE 6MT Sedan
 
d0ugmac1's Avatar
 
Join Date: Jul 2013
Location: Salt Belt (SE Ontario)
Posts: 5,068
Mentioned: 26 Post(s)
Tagged: 2 Thread(s)
Quoted: 1152 Post(s)
Thanks: 178
Thanked 431 Times in 422 Posts
iTrader: 0 reviews
More gap = Higher Voltage

So you are forcing your coils to work harder to make the spark...probably resulting in reduced lifetime.

Nissan OEM HID, Morimoto bulbs/harness, RacingLine Y-pipe, Strut Brace, Stillen Swaybar, ETI LED Fogs,
BBK: PowerStop Powder Coated Calipers: M45 Front/Stock Rears w/StopTech slotted sport rotors
BOSE Headunit w/USB & BT (2012 update), Dunlop Signature HP (summer) / Blizzak WS80 (winter)

Altima FSMs 94-09 Useful posts: Bose Upgrade / Alternator / Bad Ground / Rear Brakes / TPMS Reset /
/ Spurious ABS / Audio Power / ABS Diag / Steering Lock / Lower VQ rad hose / VQ Belt Squeak /
/ Brake Job / RA 5% Discount
d0ugmac1 is offline  
post #3 of 11 Old 12-11-2017, 08:23 PM Thread Starter
Registered User
 
Join Date: Dec 2017
Posts: 6
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Thanks: 0
Thanked 0 Times in 0 Posts
iTrader: 0 reviews
(Thread Starter)
Thanks for your reply....

Are you referring to reduced lifetime on the coils, the cables, the spark-plugs, something else? If so, are there any sings that I can check for to see if any if these components are being overtaxed?
dannnyjos is offline  
 
post #4 of 11 Old 12-11-2017, 09:28 PM
09 Altima 3.5SE 6MT Sedan
 
d0ugmac1's Avatar
 
Join Date: Jul 2013
Location: Salt Belt (SE Ontario)
Posts: 5,068
Mentioned: 26 Post(s)
Tagged: 2 Thread(s)
Quoted: 1152 Post(s)
Thanks: 178
Thanked 431 Times in 422 Posts
iTrader: 0 reviews
Not that I know of...basically the system is designed for a 0.044" gap so...

As a rough rule, spark voltage = 3KV * gap in millimetres. So 0.044" x 25.4mm/inch = 1.11 *3,000 = 3,300V (give or take)

If you stretch that to 0.055...you'd be asking those coils to hit 4,200V each time or almost 1,000V higher than their insulation is designed to take. We don't have plug cables in these VQ/QR engines, but your spark plugs may also deteriorate faster with the more energetic spark.

Why? He asked. If there was some secret to bigger gaps, why would they not take advantage of it at the factory?

Nissan OEM HID, Morimoto bulbs/harness, RacingLine Y-pipe, Strut Brace, Stillen Swaybar, ETI LED Fogs,
BBK: PowerStop Powder Coated Calipers: M45 Front/Stock Rears w/StopTech slotted sport rotors
BOSE Headunit w/USB & BT (2012 update), Dunlop Signature HP (summer) / Blizzak WS80 (winter)

Altima FSMs 94-09 Useful posts: Bose Upgrade / Alternator / Bad Ground / Rear Brakes / TPMS Reset /
/ Spurious ABS / Audio Power / ABS Diag / Steering Lock / Lower VQ rad hose / VQ Belt Squeak /
/ Brake Job / RA 5% Discount
d0ugmac1 is offline  
post #5 of 11 Old 12-12-2017, 01:16 PM Thread Starter
Registered User
 
Join Date: Dec 2017
Posts: 6
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Thanks: 0
Thanked 0 Times in 0 Posts
iTrader: 0 reviews
(Thread Starter)
Ok,it makes sense, but I wish there was a way to tell that the coils are being overtaxed (in terms of voltage). Although these altimas do not have cables, they do have coil-packs and I've installed new boots on it (the ones that attach to the coils).

Regarding the "secret to bigger gaps" and taking advantage if it at the factory, I read this online (which is what got me started on this gap issue):

Spark Plugs: Increase The Power of Your Ride

If you search on that page for "the car manufacturer's recommended spark plug gap is not optimal! " you will find the paragraph that talks about customizing the gap.

Thanks.
dannnyjos is offline  
post #6 of 11 Old 12-12-2017, 01:44 PM
09 Altima 3.5SE 6MT Sedan
 
d0ugmac1's Avatar
 
Join Date: Jul 2013
Location: Salt Belt (SE Ontario)
Posts: 5,068
Mentioned: 26 Post(s)
Tagged: 2 Thread(s)
Quoted: 1152 Post(s)
Thanks: 178
Thanked 431 Times in 422 Posts
iTrader: 0 reviews
Classic engineering dilemma. I see it as a triangle with Performance, Cruising and Cold Starting being the 3 vertices, and 0.044" gap being the centroid in the middle of the triangle.

You want better cruising...open up the gap, better WOT performance, close it down but doing either will mess with the ease of cold starting. So yes, not optimal, but it's the best setting for all conditions you might want to drive your car in.

Nissan OEM HID, Morimoto bulbs/harness, RacingLine Y-pipe, Strut Brace, Stillen Swaybar, ETI LED Fogs,
BBK: PowerStop Powder Coated Calipers: M45 Front/Stock Rears w/StopTech slotted sport rotors
BOSE Headunit w/USB & BT (2012 update), Dunlop Signature HP (summer) / Blizzak WS80 (winter)

Altima FSMs 94-09 Useful posts: Bose Upgrade / Alternator / Bad Ground / Rear Brakes / TPMS Reset /
/ Spurious ABS / Audio Power / ABS Diag / Steering Lock / Lower VQ rad hose / VQ Belt Squeak /
/ Brake Job / RA 5% Discount
d0ugmac1 is offline  
post #7 of 11 Old 12-13-2017, 01:49 PM Thread Starter
Registered User
 
Join Date: Dec 2017
Posts: 6
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Thanks: 0
Thanked 0 Times in 0 Posts
iTrader: 0 reviews
(Thread Starter)
I like that triangle analogy

Since I'm not a car person, I do want to make sure we're on the same page regarding concepts:

- Cruising means: ???
- WOT means: the car running at high revs?
- Cold Starting: the needed power to start the car on a cold day?

Thanks.
dannnyjos is offline  
post #8 of 11 Old 12-13-2017, 04:32 PM
09 Altima 3.5SE 6MT Sedan
 
d0ugmac1's Avatar
 
Join Date: Jul 2013
Location: Salt Belt (SE Ontario)
Posts: 5,068
Mentioned: 26 Post(s)
Tagged: 2 Thread(s)
Quoted: 1152 Post(s)
Thanks: 178
Thanked 431 Times in 422 Posts
iTrader: 0 reviews
Cruising: I meant environmentally responsible driving, light touch on throttle and brakes, typically lower rpms
WOT: meant wide open throttle, pedal to the metal, jackrabbit starts, lots of overtaking, hot engine, crap gas mileage...
Cold Start: conditions experienced with all engine parts cold, A/F O2 sensors offline and still heating, cold plugs, cold oil etc.

Nissan OEM HID, Morimoto bulbs/harness, RacingLine Y-pipe, Strut Brace, Stillen Swaybar, ETI LED Fogs,
BBK: PowerStop Powder Coated Calipers: M45 Front/Stock Rears w/StopTech slotted sport rotors
BOSE Headunit w/USB & BT (2012 update), Dunlop Signature HP (summer) / Blizzak WS80 (winter)

Altima FSMs 94-09 Useful posts: Bose Upgrade / Alternator / Bad Ground / Rear Brakes / TPMS Reset /
/ Spurious ABS / Audio Power / ABS Diag / Steering Lock / Lower VQ rad hose / VQ Belt Squeak /
/ Brake Job / RA 5% Discount
d0ugmac1 is offline  
post #9 of 11 Old 12-13-2017, 04:38 PM
09 Altima 3.5SE 6MT Sedan
 
d0ugmac1's Avatar
 
Join Date: Jul 2013
Location: Salt Belt (SE Ontario)
Posts: 5,068
Mentioned: 26 Post(s)
Tagged: 2 Thread(s)
Quoted: 1152 Post(s)
Thanks: 178
Thanked 431 Times in 422 Posts
iTrader: 0 reviews
and as I think about it...bigger gaps needing more voltage will take more time to develop enough voltage to create the arc...so wider gaps has the effect of retarding your timing, and smaller gaps would advance it...though I have no idea of whether we're talking a few percent or way more.

Retarded timing (aptly named) means the engine is slower to pick up rpms, and too advanced will lead to predetonation (knock).

Nissan OEM HID, Morimoto bulbs/harness, RacingLine Y-pipe, Strut Brace, Stillen Swaybar, ETI LED Fogs,
BBK: PowerStop Powder Coated Calipers: M45 Front/Stock Rears w/StopTech slotted sport rotors
BOSE Headunit w/USB & BT (2012 update), Dunlop Signature HP (summer) / Blizzak WS80 (winter)

Altima FSMs 94-09 Useful posts: Bose Upgrade / Alternator / Bad Ground / Rear Brakes / TPMS Reset /
/ Spurious ABS / Audio Power / ABS Diag / Steering Lock / Lower VQ rad hose / VQ Belt Squeak /
/ Brake Job / RA 5% Discount
d0ugmac1 is offline  
post #10 of 11 Old 12-14-2017, 01:47 PM Thread Starter
Registered User
 
Join Date: Dec 2017
Posts: 6
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Thanks: 0
Thanked 0 Times in 0 Posts
iTrader: 0 reviews
(Thread Starter)
Understood... the way I drive would be classified as "Cruising" then. Very rarely do I go above 2000 RPM.

Also, I do believe that your assessment is correct... when I moved from 0.050 to 0.055 I noticed the car taking longer to reach higher RPMs and thus, felt that it'd lost a bit of acceleration. It didn't really bother me as my main goal was to have the engine sound smooth and quiet.

If I found out (somehow) that the only thing I'm losing by using 0.055 is just a bit of acceleration and picking-up in RPMs, while the rest of the ignition system is not being compromised I'd probably leave it the way it is. Otherwise, I'll probably have to scale it back like 0.050-51.

Thanks.
dannnyjos is offline  
post #11 of 11 Old 02-09-2018, 10:13 PM
Registered User
 
Join Date: Feb 2018
Location: Fort Worth Texas
Posts: 889
Mentioned: 7 Post(s)
Tagged: 0 Thread(s)
Quoted: 154 Post(s)
Thanks: 0
Thanked 56 Times in 53 Posts
iTrader: 0 reviews
The difference in .002" mentioned above making the difference in car idle is somewhat ridiculous, at least to me. A difference of that little should make no difference at all. Only big changes like .005"+ will provided the OEM gap was chosen the the middle like all of them are. I routinely set gaps for years at up to .005 smaller to make the tuneups last longer, you set small so the gap wear runs up through the ideal number and it then takes longer to get too big to give issue. I did it on every brand car on the planet and never had any issues at all when I worked garage.

As well, the difference in coil saturation time over say .005" in and of itself will be so little (milliseconds) that the timing has no need to change due to it. The plugs never fire in the exact same place anyway, the moving around on the wire electrode of the jump-to point can have the variance .002" if using a extended tip type plug anyway. And multi-point tips that cannot be gapped are never the same (why I hate them), look at a garbage E3 plug, some of the jump-to points are close to .010" in difference and why they are crap.

Bigger gap is a good thing to work toward but you will stress your ignition parts harder. In my view ANY loss of performance means you are also shortening the life of the plugs, the loss is due to the spark getting weak enough, the mapped fuel then overrides it to begin to slowly foul the plugs and them not burning as clean will then die faster. Less spark has the same effect as too much fuel, if the ECM picks up on it it will lean the motor down to possible damage, unburned fuel being perceived as rich by it. That is potential engine problems. I'd NOT be looking at smoothness ONLY and would drop that gap back down a bit.

Retarded timing also means more heat taken by engine parts unnecessarily. Wider plug gap will lead to better idle but then the car doesn't run as well under load when the ECM goes to WFO full rich fuel, which is harder to ignite.

One way to tell if too much spark before parts start failing is to watch the plugs at the uninsulated portion right under any plug booting. Almost all cars show some slight evidence of spark jumping around the outside insulator porcelain there to get to ground rather than going through the gap as intended. Plugs tend to rust there from the humidity trapped under any covers which are commonly not nearly as waterproof as most think. The quick local heating at a cold weather start then condenses water there to rust and the rust carries spark easily. If that amount of shorting there increases to really show up as carbon streaking then you have too much of something. Once a solid short path is established there then a lot of spark will bleed off to go there and car performance drops off in a miss. I have cured innumerable engine missing issues by simply yanking plugs to then clean that area off really well and same plugs go right back in motor to no miss and they last until the next time years off in the future.

FYI, selling plugs forever proves that not all plugs are set for the exact engine and why they should ALWAYS be checked for gap before going in motor. For one, you have no idea of how many of then get dropped on a hard floor to alter the gap. It's far more than you think. For two, the maker gaps them at only ONE gap and that is the most commonly one used out of all the cars that one plug may go into. Meaning if you don't have the popular gap in your motor the plug gap will automatically be WRONG.

Cruising means low load lean and hard to ignite due to particles too far apart, BUT WOT or WFO (where I come) from means hard to ignite too due to the density, more fuel to have to light off and special problems there as well.

Last edited by amc49; 02-09-2018 at 10:18 PM.
amc49 is offline  
Sponsored Links
Advertisement
 
Reply

  Nissan Forums : Nissan Forum > Nissanclub.com Technical and Specific Interest Nissan Discussion > Forced Induction Forum (Turbo, SC, Tuning)

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Nissan Forums : Nissan Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










User Tag List

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome