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Discussion Starter #1
Recently I have installed some new components to my car, which are NGK Iridium spark plugs, and a K&N SRI. Both are great additions to the car, but on thing I have noticed recently is that when I am at a stand still the car will "stumble" or make a strange vibration. I've consulted a Chilton cobalt manual to find out what the issue may be. And so far it looks like it could be a few things, but nothing for sure. One that did cross my mind was the spark plug gapping as NGK's site said to make the gap at 0.52 in. for my '05 ls. I first I thought that seemed kind of like an extreme gap, test drove it, and it seemed fine. Today I gapped them at the 0.40 in. (stock gap setting), and the car will still make the sudden vibration repeatedly. One friend said that it may be the clutch slipping or it lost a tooth, something like that, but still not quite sure. Another that crossed my mind was the fuel filter, as my car has about 37k, and may be due for replacement. Any information or advice that anyone can give would be great. And I did try searching in the forums already for this stuff. Thanks and glad to back on the forums.
 

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If the vibration came only after installing the spark plugs I would suspect them. Did you make sure the coil pack is sitting on the spark plugs correctly? Any chance you cracked the ceramic section of one of the spark plugs? Usualy when a spark plug shorts out you feel it most under initial acceleration. Can you scan the ECM for codes? If not how about taking the car to Autozone and asking them to check for codes.

Hard to diagnose over the internet...LOL!
 

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Discussion Starter #4
I gapped them at the same time and used a wire gapping tool, and I'm not sure if we can replace any wires on 2.2L can we? The only thing I can think of that we can replace is the ignition control module, since the 2.2L uses that coil pack assembly and not an individual coil assembly like the 2.4L or the 2.0L.

Responding to 07RedSSNA, I'm pretty sure they went in correctly else I don't think the engine would have started and when I took out the spark plugs a second time I inspected all of them and took put great care into handling them especially since they have the sensitive iridium tips. However, I have thought about going to Autozone or Kragen since Pepboys, wants to charge me $90 to diagnose the engine.
 

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no way!

go to autozone. i threw a cel just last night went to autozone and 15 mins and ZERO dollars later i had the code cracked and fixed!

autozone ftw
 

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One other problem may be a bad plug all together. I put those NGK's in a car all gapped the same and one plug crapped out on me in a few hours. In my opinion these are just overpriced crap, just go back to autozone and get the stock plats. These run just as good. If it still has the same problem then you know its something else.
 

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Discussion Starter #7
Well, I went to AutoZone and they lent me a code reader for free which was pretty cool, only thing was that I didn't get any error messages when the car was on or off. Later that day I inspected them for the last time looking for any cracks in the ceramic shielding and surely enough by the time I got to the last plug on the right it looked it had two cracks! (very thin though) I told them about the vibrations and the cracks on the plug and they said that is what could be causing the misfiring. So now I have to order a new plug and replace the cracked one.

One question I have is that should I use the factory gap @ .040 or should use NGK's gap @ .052?
 

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first thing is first. get rid of the plugs and get yourself a set of acdelco. your car is set up from the factory with acdelcos and that what it will run the best on. I had the ngk's and that cooked my tower and coilpack along with my ignition control module. My cobalt with 30,000 miles on it left me on the side of the ohio turnpike. i went back to ac's and the are the best.
 

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Discussion Starter #9
What about the Bosch Platinum 4 or the IR Fusions, will those work or will they cause problems too? I just want to avoid having to pay nearly $14 a pop for those acdelcos and I think I found a wire set for my car so I'll be looking into those too. Thanks for warning ahead of time though.
 

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why did you change your spark plugs in the first place?
 

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Discussion Starter #11
I wanted them for the performance and the economy, and I was told that there were better spark plugs out there to use, so I wanted to give it a shot. Won't learn if there's anything better until you try.
 

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#1 bosch's are just as junk as ngk in my opinion. i know the ac delcoos are expensive but there cheaper than replacing all your ignition stuff.($300) save yourself some money and spend the money now.

#2 the cobalt dont have plug wires they run off a tower setup and coil packs.

you'd be better of running a straight single plug than anything like the platnium 4
 

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I wanted them for the performance and the economy, and I was told that there were better spark plugs out there to use, so I wanted to give it a shot. Won't learn if there's anything better until you try.
Been there...done that. In the past I used to do that too -- looking for more power from spark plugs. I found that on the dragstrip plugs DO NOT make enough difference to make it worth the effort. Also remember that GM didn't just pick a plug out of thin air -- they spent considerable amounts of time and money to find the plug that works best in your engine. If you are going to go that route I suggest you set the plugs to factory specs because it does affect your coils -- remember too that all components of the ignition system need to be considered. If you want more economy then the easiest money-saver is the control of your foot on the accelerator pedal:)
 

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Discussion Starter #14
Well thats what they had under wire set at kragen, they just called them boots instead and they are the stock boots that our car uses.

There's no real sense in replacing the coil packs right, those should still be good. Or should I replace them after using the NGK's?
 

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Well thats what they had under wire set at kragen, they just called them boots instead and they are the stock boots that our car uses.

There's no real sense in replacing the coil packs right, those should still be good. Or should I replace them after using the NGK's?
Only replace coils/coil packs if you find them bad. Replace the one cracked sparkplug, gap it to the factory specs, and see how your engine runs. If you still have your original plugs you can put them back in and see what happens too.
 

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Discussion Starter #16
Well then I guess I'll have to do just that then. One question though, how can you tell if a coil is damaged or not, is there anything I should be looking for?
 

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I usually stick with bosch and I just picked up yesterday bosch platinum 2 plugs,might go back and trade them in for the platinum 4,I had just regular bosch platinum plugs on my car and they work fine,I never use anything else except bosch.
 

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So probably a bad idea to get iridium plugs? That sucks cuz I literally just picked some up like 10 minutes ago, but I decided not to install em cuz it's raining and I don't have a garage. I wanted to get them cuz you need one step colder plugs before ever doing any forced induction, and I wanted to get all prepared for that...
 

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Discussion Starter #19
That's what it seems like just make sure you gap them to factory specs. Also inspect them and make sure that the ceramic shield isn't cracked like mine, or else you get craptacular misfiring, and you will hate it. Check for anything else wrong with the plug too. Also use wire gapping tool, because if you use a gapping coin there's a high chance that you can break the sensitive tip. Just refer to the first couple of posts to get you going if you dare. Meanwhile I'm still going to try experimenting with iridium plugs. I have no doubt that there has to be a least one that works, as I highly doubt that we are only limited to Acdelco's. If you do install them let us know how it turns out, so we have an idea of what we can use.
 

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Discussion Starter #20
Well this is my final test with iridium spark plugs, before I have to resort back to stock. I went to Kragen to pick up the new spark plugs, which were the Bosch Platinum IR Fusions, took out the NGK's, and replaced all the boots/coil pack (I didn't want to risk any damage from any of the other components so I replaced them all). When I took out the NGK's the spark that was damaged actually looked worse than the first time I looked at them, it almost looked like a chunk of the ceramic shield was gonna pop out! The whole installation was much quicker, considering the Bosch don't need to be gapped. Made sure that everything was in place, started the engine, and the start up was clean. The engine was completely silent when inside the car, and I let the car run for about 3 minutes, while parked. Then I started to driving and as far as I can tell, no misfiring, milage was increasing much faster, throttle responce seemed noticably better, and acceleration was noticable too. Not saying that NGK is a bad company (maybe I just got unlucky), but the Bosch are good plugs. I'll post again after about 1,000 miles worth of use and tell you guys if anything happens with these, or God willing clear sailing the whole way. Thanks for all the advice everyone, I appeciate it greatly. :)
 
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