[Brischke]

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

 

[iCruze2]

Nice write up man

 

[Snuze]

Just a note - 0.035" is not "normal." The factory spec is 0.029" not 0.035." However many have noted improved performance with the higher than spec gap.

Great write up though, and I love the pictures. Very helpful.

 

[EcoCruzer]

Is it necessary to put anything on the plug threads when reinstalling?

 

[Brischke]

I'm not sure about the plug threads. I didn't because I figured it didn't make a difference from how they were in there prior to me taking them out.

 

[XtremeRevolution]

I posted the specs, which were pulled directly from AllData and GM's literature. It's .033-.037 for the 1.4T and .028 or .029 (I forgot which exactly) for the 1.8.

I would put some antisieze lubricant on them, but make sure you torque them down to 18lb-ft.

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[Snuze]

I posted the specs, which were pulled directly from AllData and GM's literature. It's .033-.037 for the 1.4T and .028 or .029 (I forgot which exactly) for the 1.8.

I would put some antisieze lubricant on them, but make sure you torque them down to 18lb-ft.

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Interesting. I must have missed the post where the specs changed. My owners manual for my 2012 1.4T states gap is 0.029" which is what I'm going by. I don't know too much about AllData other than having heard of them, but are they correct, and has GM confirmed this?

 

[The Butcher]

Re-gapped to .035 this afternoon, three of the plugs were at .020 and one was at .019 which would probably explain why despite running 91 octane gas and adding a drop in k&n filter I still haven't been able to get my avg mpg above 26mpg... not sure how GM messed this one up but I'm really glad to have it fixed! It took me all of ten minutes and the car drives completely differently, no more extreme bogging down at low speeds or lagging at low rpm's and after an hour and a half of driving around tonight (50% city 50% highway) in AZ's 90 degree heat with the A/C on I'm currently averaging 31mpg, the highest I have EVER seen this car get since I've owned it! If you haven't made this modification yet it is a must, GM really needs to release a TSB about this issue...

 

[01sleeperZ]

The owners manual in my 12 Eco with manual states that the gap is to be 0.28 for the 1.4L engine and the 1.8L engine. I am concerned going to 0.35 when this higher number is not in compliance with my owners manual. Has anyone gotten Chevy to formally reply to this discrepancy between the owners manual and the Alldata & GM's other literature?

 

[XtremeRevolution]

Interesting. I must have missed the post where the specs changed. My owners manual for my 2012 1.4T states gap is 0.029" which is what I'm going by. I don't know too much about AllData other than having heard of them, but are they correct, and has GM confirmed this?

Yours says .029, the below says .028, AllData says .033-.037, and GM says .033x and .037x (they got one decimal point more accurate). The gaps are extremely inconsistent out of the factory.

The owners manual in my 12 Eco with manual states that the gap is to be 0.28 for the 1.4L engine and the 1.8L engine. I am concerned going to 0.35 when this higher number is not in compliance with my owners manual. Has anyone gotten Chevy to formally reply to this discrepancy between the owners manual and the Alldata & GM's other literature?

I'll call my dealership tomorrow and confirm with them. Going up to .035 will not have a negative effect. There are numerous people now who have done this with both the 1.4T and 1.8 and experienced great results.

The fact that many people have noticed a complete absence of extreme bogging, bad hesitation, and lagging throttle after increasing their gap to what I and a few others have confirmed to be the correct spec according to AllData should indicate that this is the correct gap to be using, not a random variety from .020 to .029 as they came from the factory.

If you walk into a shop tomorrow and have them change your plugs for no reason, they will gap them to .033-.037 because that's what AllData tells them to. I trust that AllData is much more current and accurate than the owner's manual, considering nearly every mechanic's shop in the nation relies on it.

 

[spacedout]

I'll call my dealership tomorrow and confirm with them. Going up to .035 will not have a negative effect.

Glad someone is going out of the way to confirm the data, but also please refrain from making blanket statements based on very limited evidence. Changing the gap changes the resistance of the plug, this could shorten the life of the coil pack which usually isn't cheap.

Best bet for everyone is to get a confirmation from GM what the spark plug gap should be before changing anything. I'm going to check my plug gap to ensure they are all the same, but am not going past .28 until I hear otherwise.

 

[XtremeRevolution]

Glad someone is going out of the way to confirm the data, but also please refrain from making blanket statements based on very limited evidence. Changing the gap changes the resistance of the plug, this could shorten the life of the coil pack which usually isn't cheap.

Best bet for everyone is to get a confirmation from GM what the spark plug gap should be before changing anything. I'm going to check my plug gap to ensure they are all the same, but am not going past .28 until I hear otherwise.

I had posted pictures that came right out of AllData earlier, but I forgot they change URLs to prevent hotlinking and didn't think to save the data. Someone else also looked it up and found the same thing. Hence, it's not actually a blanket statement but an informed one, lest you think AllData is an unreliable source of information.

 

[coinneach]

Changing the gap changes the resistance of the plug, this could shorten the life of the coil pack which usually isn't cheap.

$96 at Rockauto for either engine, part #55561655. I'm not especially worried, as factory specs (and so far almost nobody who's reported their gaps has been on spec) err on the conservative side.

 

[spacedout]

Hence, it's not actually a blanket statement but an informed one, lest you think AllData is an unreliable source of information.

The blanket statement was the fact you claimed "Going up to .035 will not have a negative effect". Even if you add up all the people who have done this mod there is probably less than 3,000miles of data. I stand by my statement that this could have an negative effect on the life of the coil pack, if this is not the correct spec GM wants.

 

[XtremeRevolution]

The blanket statement was the fact you claimed "Going up to .035 will not have a negative effect". Even if you add up all the people who have done this mod there is probably less than 3,000miles of data. I stand by my statement that this could have an negative effect on the life of the coil pack, if this is not the correct spec GM wants.

That I agree with. If this is not the correct spec, it can have a negative effect, although respectfully, that is also somewhat of a blanket statement as it will depend heavily on the specific coils in question. I simply didn't read much importance or validity into it because I saw the AllData document with my own eyes. I'll see if I can get my dealer to give me some information.

 

[Higgs Boson]

Keep in mind All Data is not GM. It is an aftermarket company just like Chiltons, etc designed to help the after market repair shop git 'er done.

I have a father and an uncle with dealerships and I have another uncle with a repair shop that was started by my grandparents in the 40's. The repair shop uses All Data, is more expensive than the dealerships, etc. I would not use All Data to override whatever GM has to say about the vehicle they designed, engineered and constructed.

I am not saying there isn't a misprint somewhere at some company, after all, All Data may have gotten their info from GM directly, but iridium plugs are usually "no gap" plugs. Has anyone gone to Auto Zone and checked the out of box gap on a new one (same model)?

 

[jblackburn]

Iridium plugs are generally sold pre-gapped correctly. The gap also doesn't change AT ALL over the course of say, 100,000 miles.

People are told to avoid gapping them because it is so easy to damage the electrode on iridium plugs. But do it right, they can be gapped. Even though they should be in the first place.

FWIW, grab the tip with pliers to increase the gap. Do one and you'll figure out about how much force you'll need. Never force anything against the center electrode.


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[XtremeRevolution]

Just got off the phone with Phillips Chevy in Frankfort, IL.

They specified the following spark plug gap for the 1.4T: .033-.037. For the 1.8, they specified .028.

You may call them yourselves if you don't believe me.
815.469.2323

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[01sleeperZ]

Just for the record, I checked my plugs last night and one was at .025 and three at very close to .028. I set them at .032.

 

[XtremeRevolution]

Just for the record, I checked my plugs last night and one was at .025 and three at very close to .028. I set them at .032.

Still a hair under GM's spec, but good job on fixing it.