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Discussion Starter · #1 ·
I'm creating this thread to increase exposure of what appears to be a very common issue (affecting 100% of Cruzes so far). This stemmed from the following thread:

http://www.cruzetalk.com/forum/27-fuel-economy/6468-spark-plug-gap-fe-1-4t.html

My original experiment was to increase spark plug gap over what they are gapped from the factory and test for measurable gains in fuel economy. What I didn't realize was that I had actually gapped them to the correct spec, and they were gapped much too small from the factory.

AllData specifies a spark plug gap of .033-.037 for the 1.4L Turbo motor. Reports so far have come back with .024, .025, .026, and .029 as measured spark plug gaps from the factory iridium plugs. These should have been pre-gapped from the distributor, but clearly weren't.

Coinneach checked his spark plug gap on his Cruze LS with the 1.8L N/A motor and found a .020 spark plug gap, which is absurd for a N/A motor and is smaller than he or I have ever seen before in any engine. He increased that to .035 and had the following to say when I asked if he noticed a difference:

Like a whole new beast. It's not quite as zippy as the 1.4T in the Eco that I drove when I was shopping, but it's a *censored* of a lot snappier now.


I currently don't know what AllData specifies for the Cruze LS, but if someone can get that information into this thread, it would be of great benefit to everyone. Hopefully, someone will get a tutorial/video made soon. There are significant performance and fuel economy gains to be had by correcting the spark plug gaps on these cars.
 

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Thanks X, i seen the the other thread before, I will be checking both cars.
You have a link to were it calls for .33-.37 gap on 1.4L motor?

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Discussion Starter · #3 · (Edited)
Got this from a buddy of mine on w-body.com. Click to enlarge.

ECO:


LS




What I want to know is why AllData specifies a smaller spark plug gap for the 1.8L than it does for the 1.4L Turbo. It's usually the other way around.

That said, I can't see anything wrong with gapping the 1.8L motor bigger than the spec. There definitely won't be any danger of spark blowout with that motor running a .035 gap.


Edit: the images got screwed up for some reason.

In any case, AllData and GM both call for .033-.037 on the 1.4L Turbo, and .028 on the 1.8L N/A motor. I would say everyone can safely run .035 regardless of motor.
 

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...ah, but the "real" question should be: "...what does GM specify the gap should be?"
 
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Discussion Starter · #5 ·
...ah, but the "real" question should be: "...what does GM specify the gap should be?"
Same thing. That has already been checked and verified in the thread I linked in the initial post, only they went a bit further and added another decimal point of value.
 

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Cuda, the gap specs aren't the problem; it's that our cars are being delivered with incorrectly gapped plugs.
 

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My question (and really everyone's should be) is are the plugs gapped wrong or is GMs listed spec wrong?
 

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Discussion Starter · #8 ·
My question (and really everyone's should be) is are the plugs gapped wrong or is GMs listed spec wrong?
My guess is that since everyone's findings are all over the place and are nowhere near accurate that GM's and Alldata's listed specs are correct. Seriously, .020 on the 1.8L? That's laughable.
 

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My question (and really everyone's should be) is are the plugs gapped wrong or is GMs listed spec wrong?
Considering the increase in economy and performance we've uniformly seen after regapping, I'd say the former.
 
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Discussion Starter · #11 ·
How the ef do i do this, and where did i put my dad's spark plug ratchet thing.
You do this one step at a time, patiently and slowly. I believe it's the smaller of the common spark plug sockets to get it out. You'll also need a torx bit, but I don't remember what size it was. Don't adjust gap with one of those coin looking things; you'll need proper feeler gauges. You might otherwise damage the plug as it's an iridium tip. Once you get the engine cover off, the coil bar is right in the center with the two bolts that need removing, and you can wiggle it right out (again, patiently and slowly). Check inside the boots to make sure the springs didn't bind, and proceed to the spark plugs.
 

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You do this one step at a time, patiently and slowly. I believe it's the smaller of the common spark plug sockets to get it out. You'll also need a torx bit, but I don't remember what size it was. Don't adjust gap with one of those coin looking things; you'll need proper feeler gauges. You might otherwise damage the plug as it's an iridium tip. Once you get the engine cover off, the coil bar is right in the center with the two bolts that need removing, and you can wiggle it right out (again, patiently and slowly). Check inside the boots to make sure the springs didn't bind, and proceed to the spark plugs.
It's the 5/8" spark plug socket and T-40 torx bit.
 
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You do this one step at a time, patiently and slowly. I believe it's the smaller of the common spark plug sockets to get it out. You'll also need a torx bit, but I don't remember what size it was. Don't adjust gap with one of those coin looking things; you'll need proper feeler gauges. You might otherwise damage the plug as it's an iridium tip. Once you get the engine cover off, the coil bar is right in the center with the two bolts that need removing, and you can wiggle it right out (again, patiently and slowly). Check inside the boots to make sure the springs didn't bind, and proceed to the spark plugs.
I've only just used a coin thing. What do you suggest we use for gapping them correctly..?
 

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How much does that cost

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Adjusting the gap, assuming you have the tools, costs nothing but maybe 15 minutes of your time. The gap tool shouldn't cost more than $3 or so at Pep Boys, Autozone, etc.
 

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Adjusting the gap, assuming you have the tools, costs nothing but maybe 15 minutes of your time. The gap tool shouldn't cost more than $3 or so at Pep Boys, Autozone, etc.
The cost of the tool is my question. Thats the tool linked above? Or just a coin gapper? It looks like itd be more than $3.

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Discussion Starter · #20 ·
The cost of the tool is my question. Thats the tool linked above? Or just a coin gapper? It looks like itd be more than $3.

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Coin gappers aren't recommended with iridium plugs. You can try it, but there's a chance you could break the tip.

Not sure how much the other tools are.

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