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DIY re-gap factory spark plugs

216K views 473 replies 188 participants last post by  Sunline Fan 
#1 · (Edited by Moderator)
Go back to COMG- The Cruze Owner's Maintenance Guide

http://www.cruzetalk.com/forum/10-powertrain/7761-gms-official-statement-regarding-spark-plug-gaps.html

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So a lot of people have mentioned (mainly xtreme revolution who has helped to point this out) that the spark plugs are gapped incorrectly from the factory.

I checked on mine which were way off (around .02) , took about 20 minutes to get them to normal (.035), haven't driven it around yet to test but am happier knowing its done. Here is a quick write up of this process:

Tools needed:
5/8 inch spark plug socket
T30 Torx Bit
Spark Plug Re-gapping tool ($1.99) at any autoparts store. Be careful to check the sizes make sense (I'm pretty sure the one I received was put together backward - notice .045 is smaller than .035)




Pop off engine cover




Remove the two torx screws
Wiggle out the spark plug boots




Not sure why this boot has so much dust



Remove the spark plug and re-gap as shown in this video

Spark Plug Gap - NGK Spark Plugs - Tech Video - YouTube

Reverse the procedure and put everything back together.

Have a few beers... not many things to work on yet with this car, might as well enjoy the small tasks.

[HR][/HR]

EDIT: Since Brishke created this excellent post we have discovered that the ignition coil springs in the boots are frequently jammed into the side of the boot. They need to be straight. The easiest way to do this is to take a long skinny screwdriver and gently insert it into the end of the boot and into the end if the spring. Gently wiggle the screwdriver until the spring comes free. Remove the screwdriver. This needs to be done on all four boots.

- Mike
 
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#171 ·
.035 is perfect as long as you stay on the stock tune. If you decide to tune your Cruze, you'll want to look at .028.

Actually, .035 should be okay for tuned vehicles, as long as you are feathering the acceleration. WOT does not like .035, you'll miss pretty badly. I may try .035 again, since I'm on an 'economy kick' with my Cruze, lol.
 
#172 ·
I read what everyone was saying so I had to try it. My 1.4t had pretty much all .027's. changed them out last night with .035's. only thing is the idle, after driving it a bit, and then stopping sounds louder, but acceleration seems fine. Not too much pick up compared to before. I really was hoping to get a little something from this.. And yes i did gap it right. I checked atleast 5 times each one lol.


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#173 ·
in regards to my last post, i also changed out my air filter with an incompatible AEM filter it seems. supposedly only made for 1.8l but it seemed to fit snug. so i dont know why they say it's not compatible. not sure if that would totally make the idle feel extra loud or not. any ideas?
 
#174 ·
ok i regapped today , one was at .019 the others were around .022, i regapped to .032 for a happy medium between .030 and .035 it does have a smoother pull but if im sitting idle and rev it i get a slight stumble as it comes back to idle around 2000rpm, and today on the way home it had a one time stumble just sitting at the stoplight, i figured maybe it needs to relearn? if it continues to stumble im going to regap to .030 and go from there
 
#177 ·
Checked and re-gapped to .034. 650 miles on it so far. Factory was pretty consistent - from left to right - .024, .025, .025, .024. Since I haven't driven it other than to make sure it was smooth, I don't really have an opinion on what might have changed yet. 2013 2LT.
 
#178 ·
Followed suit with the rest of you guys. 2013 LTZ RS - .019 -.025 -.022 - .022 - Car had the 'fall on it's face' effect and wasnt smooth thru the powerband. Set to .034 and I can absolutely feel a difference. Thanks so much for this thread. For $4 (gap gauge and antiseize) I save a trip to the dealer and "We cant find a thing wrong, its running great" speech. Although I have a thing about putting a wrench of my own to a brand new car, I have certainly learned that doing things myself is so worth it. Now lets see what happens when I go in for the buzzing heater tube dealio.
 
#179 ·
I checked my plugs about a week ago on my 2012 LS, at about 350 miles. They were between .019 and .022. Regapped to .35 and made an amazing difference. I was never able to get off the line without stumbling a bit (manual tranny), but after regapping, that is now silky smooth, as well as 1-2 smoothing out. The car just pulls so much better and smoother, and I have not noticed any difference at idle. I can't speak to any mileage change since I've only put one tank in her, and she's still breaking in.
 
#182 ·
Those of use running at 0.035" are on the stock tune. If you're running any tune, Trifecta, or otherwise, don't go above 0.028". The tuners based their tunes on the setting listed in the Owner's manual.
 
#184 ·
In simple terms, the spark plug does not have enough energy to maintain the electric arc it creates due to the pressure and airflow inside the cylinder, so it blows out. Pretty similar to a a candle that blows out due to wind. Depending on how strong the ignition coils are, making your spark plug gaps larger will eventually lead to spark blowout. That is, if you make them far too large. The end result is effectively a misfire.
 
#186 ·
EcoCruzer...From my experience id atleast put antiseize grease on the threads to prevent them from seizing to the block and causing potential damgage. Just put a small amount on the threads, dont need alot =]. Hope this helps.
 
#187 ·
Just regapped the NGK's that came stock to .035. I am running an Injen CAI & MagnaFlow dual exhausts.
What a difference in pickup & acceleration.
I have 45K on the car & will see if there is a mpg difference.
Just the difference in performance is worth the difference.
The engine is running cooler without all the stock intake plumbing.
Need the air in Arizona.
 
#188 ·
You may see some MPG improvement based solely on the fact that you can stay in a higher gear when going uphill and lower RPM up shifts while accelerating.
 
#189 ·
Just got back in from doing this and WOW! The sparkplugs were at like .018-.022! I set them all at .035 and the loud ticking at engine startup went down quite a bit, maybe I'm just delusional on that but I'm sure it'll have better response now.

I was also surprised that it had NGK's as opposed to a bosch set, I was happy about that as I like to run NGK's in my other vehicles too.
 
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#196 ·
The lifters do make some noise when sitting at idle. This is normal and makes the car sound kind of like it's dieseling. You could be hearing that as well.
 
#199 ·
I just did this as well on my 2011 Eco with 15k on it. The plugs were all at .026 except one, which was at .028. Re-gapped to .035ish (had two different gapping tools and they were about .003 off from each other).
 
#200 ·
Mine were all around .020. The job overall was very simple. Way to go GM for making this Cruze (as far as I've seen) simple, but boo that I have to do this to begin with. The hardest part was getting them to the correct gap without going over. Took it for a quick trip down the road, and after warm up, I punched it. Seemed to me to accelerate faster, could be just a psychological trick out from thinking I did my engine more justice than I really did it.
 
#203 ·
Throttle response will have improved. If you have a manual transmission, the difference is very noticeable. It's not so noticeable with the automatic transmission, but fuel economy should improve slightly. I think people were seeing 1-2mpg better.

I thought 35 was the optimal for a passenger car for tire pressure. Why is yours at 44?
You might be interested in this thread:

http://www.cruzetalk.com/forum/27-fuel-economy/6068-my-tread-depth-log-max-sidewall-pressure.html
 
#202 ·
Off topic, but the answer is that the ECO's LRR tires are rated for 51 PSI Cold. You get better fuel economy with higher tire pressure by lowering rolling resistance. Remember, car manufacturers recommend tire pressure based on comfort, safety, and handling, in that order. Higher pressures transmit more road bumps through to the passenger compartment.
 
#204 ·
Just checked mine today and found them all at around .025. Bought a wire type gap tool since the coin type can break the electrode off of iridium plugs. Didn't know this and I'm glad I stumbled upon this info since I've been running iridium in my cars for years but never had to gap them before.
 
#205 ·
Just did this. Between .025 and .030 on all four of them. I couldn't tell any more precisely because my gap tool only goes .025, .030, .034, .035, .040.

I set them all at just barely fitting .034 through.

Started the car and it sounded like it was clicking. Like a fast clock.

I read someone else's post that said the car can normally sound like a diesel, so I took it for a spin anyway.

After two weeks in the shop, I have a running car again.

Just kidding. The car drove great! It seems like it has bigger balls now. I don't think it's in my head either.

I will update again on fuel economy. Right now I have Premium in the tank mixed with a little Regular. Probably about 89-90 Octane.

It used to sound very bad on cold mornings (~20*F). I will note this in the above update after I go through a tank or two.

Cheers!
 
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#213 ·
Started the car and it sounded like it was clicking. Like a fast clock.

I read someone else's post that said the car can normally sound like a diesel, so I took it for a spin anyway.
I regapped my plugs, one broke in the process. Didn't see or think I broke anything, but the last plug had a huge crack down the side...oh well, got a new autolite iridium from AutoZone. Anyways, I turned the engine on, and heard the same clicking. Like a very fast ticking sound. I had never noticed it before so I didn't know if it was normal or not.

Is it something to be worried about?

P.S. Running on 87 octane, it doesn't feel much different, and about the same mpg so far, although only about 20 miles have been driven on it.
 
#206 · (Edited)
3+ decades w/ Southern Co yielded some info.

1. Spark plug threads; Use a minimal amount of Copper based antiseize.
Loctite C5a copper based antiseize.
Amazon.com: Loctite C5-A Copper Anti-Seize; 51147 C5A 8OZ BT [PRICE is per BOTTLE]: Sports & Outdoors

Also use a pinprick amount on the plug boot end of the plug, then burnish it in(rub hard), &wipe off.

2. Use silicone (dielectric) grease on the rubber plug boot. Cruze/Hemi style boots use on outside too.
Apply both products sparingly.
Permatex 22058 Dielectric Tune-Up Grease, 3 oz. Tube : Amazon.com : Automotive

Per GM ser manual, use silicone grease on wiper blades & door gaskets (clean first)
 
#207 ·
I'm at the end of my second tank of gas, and am averaging at or below my original gas mileage.

I think my plugs were consistent in gap size before increasing each one to ~0.34 which is why I'm not really seeing any better gas mileage.

Oh well.
 
#208 ·
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