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Discussion Starter #1 (Edited)
I did all of my engine and suspension upgrades essentially at the same time. After the install my car ran very rough. I data logged it and sent it to Vince who sent me an updated map. Ran much smoother but when i'm accelerating in third and up the entire interior will vibrate, especially the rear view mirror. Also, early in the morning I get a certain distance out and come to a red light, same place same time every day. I hear 6 knocks from the passenger side of the car and i'm not moving so it must be from the engine.

I will take a video on my way to work tomorrow but wanted to get some wheels turning in the mean time. I plan on data logging again but my dog just are the power cord to the computer. Any ideas what is making the rattle so hard and possibly why the engine knocks?
 

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Discussion Starter #3
I was thinking about getting larger injectors. Do you thinkthis might remedy the problem?
 

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Discussion Starter #5
Seriously, no one?!
 

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Seriously, no one?!
Thread refers to interior vibrations but post seem to refer to engine problems.
Since you haven't listed what you did to your Cobalt in this thread and we'd have to search all your post to find out, it is hard to diagnose. But the second to last noise really sounds like spark knock, so retarding the timing quicker would be a plus if Vince can set these parameters. And the last noise sounds like dieseling. Now this can be caused by many things, plugs running to hot, again timing and octane value in your gas. Have you tried high octane just to see how it would work? Do you still use OEM plugs. Did you change your mounts for stiffer ones like polyurethane? Because these will transfer a lot more vibrations to the cabin.
 

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Discussion Starter #7
I know. It ended up being two different issues. My garage has all the mods on the vehicle but complete SS suspension and poly mounts, intake, 2.4 IM and TB, 2.5" header.

I knew that more vibration would transfer but I haven't heard of anyone elses rear view mirror rattling like I got two 12" subs blasting.

I was planning on getting new plugs soon anyways but they were OEM ac delco's replaced in August last year. I'll also talk with Vince about possible solutions on his end.

I have not tried a higher octane gas, I was told by a mechanic friend that I should run with the gas that I got the car tuned with. What octane level are we talking?
 

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I'm not saying U should run High octane all the time. It would be for diagnostic purposes only. Next time your car is almost empty get 4 gallons of highest octane you can find and see how it runs. If it gets worst then fill-up with regular gas. This will give Vince one more clue as to what to do with timing. If your car engine smooths out with high octane he will know for sure to pull back on timing a bit. It won't hurt the car.
 

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Discussion Starter #9
So 89 or 91?

---------- Post added at 11:36 AM ---------- Previous post was at 11:35 AM ----------

oh, and do you have the gap size for plugs, 05 ls manual?
 

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So 89 or 91?
highest octane you can find

oh, and do you have the gap size for plugs, 05 ls manual?
The plugs if purchased from Dealer will come pregapped for your vehicle with a protective cap. They do not recommend that you attempt gapping plugs because of the iradium tips. But you can verify that they are 1mm if you're careful.

2005 Engine Specifications

Engine Spark Plug Gap

2.2L L4 F Automatic or Manual 0.04 inch (1.0 mm)

2.0L L4 (Supercharged) P Manual 0.04 inch (1.0 mm)
 

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Discussion Starter #11
I'll let you know tomorrow. I'll be low on gas when I get home tonight and will run it on 91 on the way to work tomorrow.

Thanks.
 

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Discussion Starter #12
Plugs in and ran for 75 miles. Didn't hear the knock but really just forgot to listen for it so I'll try tomorrow morning. Going to fill up with prem gas on the way home and see if that helps at all.

I'm starting to think the vibration is from parts touching, possibly header and sway bar. Only becuase I got the long tube header and larger sway bar. It's the only parts that are a different size than what came with the car.

I'll hop under the car this weekend to see if that could possibly be the problem.
 
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