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Administrator, Resident Tater Salad
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Discussion Starter #1 (Edited)
UPDATE: For those that don't want to read through the 2348972347892 pages of this thread, we have found that the following plugs seem to work best in the 1.4-Liter engines:
-BKR8EIX-2668 (iridium plugs), ~$25, expect ~10-15k regaps on these, ~40-50k overall life.
-BKR7E-4644 (nickel/copper plugs), ~$8, expect 15-25K out of these plugs, with a regap or two required at 5-8k intervals on stock tune.

Set initial gaps @ .028". Higher gaps will start to blow-out as the gaps increase.

So for what it's worth, some of you may remember that I was saying I had hesitation that felt like timing pull, even on 93 octane during winter months. I believe I got that one taken care of with a new stock ECU tune from Chevrolet, as for the most part, it behaved much better after that.

However, with the AC on fan speed 3, and especially 4, on a hot day (85+), and even sometimes just randomly when it's not that hot, I'd feel a strong timing pull from 1850-2750 RPM...jerky acceleration and the car just felt...slow. Pinging right off the knock sensor, about 3-4 times per gear under acceleration. With the AC off, it's fine unless I'm sitting at a light for a while.

I ordered the copper NGK version of the same heat range plug that's in the car (BKR7E) and dropped them in today. Perfect day to test - lots of traffic, lots of stoplights, AC on fan speed 3/4, and 94 F outside.

Once the ECU "adjusted" after a few seconds, I could not get the car to jerk WHATSOEVER. Very happy. Acceleration is smooth from a stop all the way up to 5500 RPM, and the car drives like what I feel like it was made to drive like.

I don't know why this made a difference, other than my experience that turbo cars do not like platinum plugs and perhaps iridium have the same effect on them. The old plugs look like they're burning just fine and are clean.

EDIT:
Many of us have found that the .035" gaps are a little bit optimistic - our cars will start to blow out after not too long as the gaps grow. I'd recommend starting in the .028-.030" range. Check your plugs again after 10,000 miles and readjust.




Old iridiums
 

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How long do you expect the copper plugs to last? I know one of the reasons GM with the iridium plugs was to reduce the frequency of plug changes.
 

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Glad to hear it!

And yeah, with plug changes being stupid easy on the 1.4T, changing them every year is fine. Although the wife would shoot me for spending more time than needed on the car...
 

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Discussion Starter #6
Well, spent part of the day hooning around back roads, then part of the day running errands with the AC on in-town.

There is NO bog off the line in 1st gear with the AC on 3 or 4 like there was before, power delivery is smooth in between gear changes as well, and no jerking/apparent heat soak problems (90F outside). I thought that all of this was just characteristic of this car in hot weather, so I'm completely surprised. The midrange torque between 3000-4000 RPM feels great too.


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For $10 will give it try - Sounds like a nice improvement.
 

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Actually, copper plugs will probably not need replacing each year. If they are running clean and not fouled, simply closing the gap to compensate for wear could be all that's necessary. I wouldn't hesitate to think you might get 2-3 years out of a set of copper plugs if the gap is maintained properly. The biggest thing would be to make sure they're not getting fouled over time.
 

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Discussion Starter #9 (Edited)
Honestly, those of you that are tuned...I'm not sure if this will make a difference. It sounds like Vince (and others) have done pretty well with improving the drivability of these engines on the stock plugs.

Most people I've heard complain about jerky acceleration seemed to be using regular gas. Unless anyone else here has this issue on a stock Cruze, I'm wondering if I have a knock sensor that is just overly sensitive.


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Discussion Starter #11
Well, if an A/B comparison with the stock and copper plugs makes a big difference for you then you've improved something with the coppers, whether or not you have a hyper sensitive knock sensor.
It makes me think that the plugs themselves ran on the hot side and were definitely causing pre-ignition when the IAT was super hot. On top of that, Chevy's stock tune is ULTRA-conservative (makes sense, for warranty reasons) in terms of cam timing and knock retard. "What was that?!? A ping?! PULL POWER NOW!". Unfortunately, while it may keep the engine very safe and Chevy out of replacing it, it makes for crap drivability since it both dumps off boost and changes the cam timing, especially on the octane they rate the Cruze to run on with the stock iridium plugs.

When I first got the Cruze, I was running regular on the wildly-out-of-spec gaps on the plugs, and it just about stalled out when taking off in the summer on a hill with the AC on. Even still, with the intake resonator and re-gapped plugs with high octane, it seemed like it struggled to get going from a stop.

If smoothness is much improved with the Trifecta tune, he essentially dialed back that sensitivity at low RPM, much in the same way that replacing knock sensors on the early Toyota 1MZ-FE yielded significant power gains (not many people were interested in tunes then - it just wasn't "easy" like it is with a laptop and OBD cable these days). I think that's what Chevy's updated tune did to my car as well - some engineer realized that they had built way too much of a precautionary buffer into the tune.
 

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I think that's what Chevy's updated tune did to my car as well - some engineer realized that they had built way too much of a precautionary buffer into the tune.
I hope you're right, and some day I can see the difference between the '12 and '13 tunes in HPTuners. Then we could see exactly what's what and then speculate why. :)
 

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Honestly, those of you that are tuned...I'm not sure if this will make a difference. It sounds like Vince (and others) have done pretty well with improving the drivability of these engines on the stock plugs.
I am tuned and I still get some hesitation on take off with the A/C on. My plugs are schedule to arrive between Aug 13 and 16. I will report on the results.
 

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Discussion Starter #14 (Edited)
Filled with 87 E10 today just out of curiosity and switched on the AC (3-max). 85 F outside.

It actually drove completely fine. No bog from a stoplight, no jerkiness or hesitation. I felt heat soak once after sitting at a light for 5 minutes, but it was just slightly slower acceleration and no jerk-you-around knock retard.

Next weeks supposed to be in the 90s again, so I'll see how it behaves.

I really can't believe all this knock was a result of the plugs themselves. Kinda makes me think Chevy got their programming right and the plugs were just a marketing decision.


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My Plugs arrived late Thursday but did not get a chance to install this weekend. Will try and install tomorrow after work. Expecting mid to upper eighties starting Tuesday.
 

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Changed out the plugs - will have to wait till tomorrow to check for hesitation/bog with A/C. It is only in the low 70s now, tomorrow will be mid to upper 80's and humid. However did run it for a few miles in eco mode and after the plug change it has smoother power delivery and pulls a little harder than with old plugs. Old plugs looked fine and was careful and did not break my coil pack.
 

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Oh and since I am tuned gapped to .030.
 

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Changed out the plugs - will have to wait till tomorrow to check for hesitation/bog with A/C. It is only in the low 70s now, tomorrow will be mid to upper 80's and humid. However did run it for a few miles in eco mode and after the plug change it has smoother power delivery and pulls a little harder than with old plugs. Old plugs looked fine and was careful and did not break my coil pack.
Looking forward to the update!
 

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Went out for lunch but only 82 degrees and 39% humidity (per my weather.com app), however with the A/C on the highest fan setting, I am not getting any bog or hesitation where I usually I get dangerous bog/hesitation pulling across on coming traffic up a slight hill with the A/C on. Results seem very good so far. I would like to see how it does with higher temps and higher humidity and a passenger. So far - very good mod for very little cost.
 
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