I gapped mine to 35 and see no difference in mileage or power over 600 miles even though I really wanted to. plugs were gapped at 25 stock. be careful gapping these plugs, you can bend or break the electrode easily. use pliers to pull the ground strap up and then bend them down on the ground. a normal gap tool will ruin your plugs.
Are Your Spark Plugs Gapped Incorrectly?
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:
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.
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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I went over this in a bit of detail a few posts (or pages) back, regarding which tools to use and why. A coin-type tool is not how people should be gapping iridium tipped plugs. Feeler gauges need to be used or a specific spark plug gapping tool.I gapped mine to 35 and see no difference in mileage or power over 600 miles even though I really wanted to. plugs were gapped at 25 stock. be careful gapping these plugs, you can bend or break the electrode easily. use pliers to pull the ground strap up and then bend them down on the ground. a normal gap tool will ruin your plugs.
Try putting your gaps back to .025 and see if you see a difference again. I know I felt a difference for sure, but it was mostly at lower RPMs, which the auto transmission won't really let you get into a whole lot.
Technology has come a long way my friend. They still use .060 now, and quite frequently at that. I believe most of GM's V6 and V8's use that gap.
Beg to differ. You can certainly use a 27, but 40 is more snug and doesn't slop around like a 27 or 30. Yes, even on the drums.Actually it's a T-27 torx (same size that you use for your rear brake drum screw removal).
Agreed here. I ended up using my T27 a few minutes ago, but it wasn't as tight as I like it to be. Fortunately, these aren't on there very tight from the factory and can be removed even with a bit that goes into the end of a screwdriver.Beg to differ. You can certainly use a 27, but 40 is more snug and doesn't slop around like a 27 or 30. Yes, even on the drums.
I gapped my plugs to .040 and went out for a drive, scanning for KR and misfire events with Torque. Not a single issue. I'll be scanning the whole way to work tomorrow. I think I'm content at .040. That's only .003 larger than the GM/Alldata spec. Engine is smooth across the powerband and feels great.
I'll report my fuel economy when I fill up this week.
I would like to look into this for anyone who has confirmed that their spark plugs are gaped incorrectly. Please send me a PM with your name, address, phone number, VIN, current mileage and the name of your dealership. I look forward to hearing back from and assisting anyone with this issue. If you have any other questions please feel free to contact me as well.
Thank you,
Stacy Chevrolet Customer Service
Thank you,
Stacy Chevrolet Customer Service
What will you be able to do about this problem.I would like to look into this for anyone who has confirmed that their spark plugs are gaped incorrectly. Please send me a PM with your name, address, phone number, VIN, current mileage and the name of your dealership. I look forward to hearing back from and assisting anyone with this issue. If you have any other questions please feel free to contact me as well.
Thank you,
Stacy Chevrolet Customer Service
Sent from my Droid
Both of my cruzes were at .024
They are now at .035
Sent from my DROID X2
They are now at .035
Sent from my DROID X2
Stacy,I would like to look into this for anyone who has confirmed that their spark plugs are gaped incorrectly. Please send me a PM with your name, address, phone number, VIN, current mileage and the name of your dealership. I look forward to hearing back from and assisting anyone with this issue. If you have any other questions please feel free to contact me as well.
Thank you,
Stacy Chevrolet Customer Service
Can you look into the issues with coolant leaks/smell? This seems to be a major issue and many people would like to know what GM is doing about it. I'm sure that lots of people, including myself, feel like the Cruze is a ticking time bomb with all these issues people are having.
Sent from my Autoguide iPhone app
My bad! You are right in that T-40 IS the correct size for the M6 X75 bolt.Beg to differ. You can certainly use a 27, but 40 is more snug and doesn't slop around like a 27 or 30. Yes, even on the drums.
As for my ride to work today it did feel like the car had a smoother low end pick-up but couldn't tell if the gas mileage was affected as the expressways were all fk'd up this morning.
Write a case for it, file a complaint with engineering, find you a dealer and set up an appointment for you to take it in and have the dealer do it. Maybe with enough reports and complaints, GM will wake up and realize they're not gapping the plugs correctly when they're delivering the cars to the dealers.What will you be able to do about this problem.
Sent from my Droid
I also can't tell if gas mileage improved yet. If it does, it will probably be in the range of 1-2mpg. I did also notice a smoother low end acceleration.My bad! You are right in that T-40 IS the correct size for the M6 X75 bolt.
As for my ride to work today it did feel like the car had a smoother low end pick-up but couldn't tell if the gas mileage was affected as the expressways were all fk'd up this morning.
I had to copy this over here as well:
If anyone reports hesitation at lower RPMs, looks like we have a solution!Got bored during my lunch break and decided to check mine. All 4 varied between .024 and .026. I set them at .035. It literally took 10 minutes.
On the way back to work I did notice the low RPM hesitation is gone.
I noticed the car ran better at low RPM's. I think the Eco MT's and other MT-car folks are noticing the most benefit since the AT will shift well before the RPM's involved. The improvement was noticed the most between 1000 and 1500 RPM's. I spend a lot of time between those two RPM ranges.
Is this correction doing much for those with Cruzes with AT?
There should be a definite increase in fuel economy. It may not be much (1-2mpg), but it's something nonetheless. AT Cruzes may not notice it as much, but there will also be a slight increase in performance.Is this correction doing much for those with Cruzes with AT?
i see no reason to expect a mileage gain and no reason to predict a 1-2 gain either but i am certainly hoping that there is.There should be a definite increase in fuel economy. It may not be much (1-2mpg), but it's something nonetheless. AT Cruzes may not notice it as much, but there will also be a slight increase in performance.
this is one of those cases where i think your talking out your ass but hope your right
just re-gapped mine last night....Did notice an improvement for sure...Seems like a good thing to me!!
i dont trust my butt meter at all but there are so many people here reporting an improvement in low rpm driveability i am starting to believe.... cant wait for the mileage reports to come in.just re-gapped mine last night....Did notice an improvement for sure...Seems like a good thing to me!!
As a result of these bad spark plug gaps, we're getting:i see no reason to expect a mileage gain and no reason to predict a 1-2 gain either but i am certainly hoping that there is.
this is one of those cases where i think your talking out your ass but hope your right
1. less than optimal fuel burn
2. hesitation at low rpms
As a result of correcting the gap, the car is:
1. a whole new animal (coinneach)
2. getting much better low end power delivery (everyone with a manual transmission)
3. running smoother throughout the powerband
The moment you start gaining power and not using more fuel to gain that power, you are gaining efficiency, which means you can use less fuel to go just as far, thus increasing fuel economy. The question to be determined is not whether or not there will be a gain, but how much that gain will be.
1-2mpg is merely my speculation. I would be talking out of my ass if I guaranteed a 1-2mpg gain.
I would think that with a bit more power in the low rpm's that it should help with the fuel mileage...I guess we will see....I have 20,000 miles on mine and man the plugs looked really good....a nice clean burn on them....although the gaps were all over the place between the 4.....i dont trust my butt meter at all but there are so many people here reporting an improvement in low rpm driveability i am starting to believe.... cant wait for the mileage reports to come in.
I am thinking and this is just a guess that they gapped them smaller do to GM's no tune-up for 100,000 miles...as over time I would think they gaps would get wider so that they would end up at .035 after the 100,000 miles.....just a guess though
41 - 60 of 546 Posts
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