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06cts-v
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Discussion Starter #1
I don't usually have to reach out for tech help... and i've over utilized the search function so here we go....

Platform:
2006 cadillac CTS-v
LS2 AFR225 heads, Custom grind Pat G cam with EPS lobes

Started off with a broken valve spring. I replaced them all. Checked the pushrods for damage they all checked out.

When i put it back together i would get an intermittent miss. Then with throttle or letting off throttle it would clear up. Now it has a constant Missfire. started one morning after i left the house and got about a 1/4 mile away. Acts the same as when the spring broke.

-compression test @ 180psi
-no codes being thrown.
-No valve train noise
-no broken springs or rod damage
-turned over by hand all rockers move thru the range
-will not rev over 3k due to cutting out and miss
- no trash or mixed fluids in oil change
- getting fuel

I replaced every spring with a new set of doubles with same specs.

No misfire code popping up as a CEL. I'm new in San Antonio, TX and all of my contacts with Shop Tool and HP tunners are in St. Louis. Not really finding actual car people here that turn wrenches so far.

in neutral it will misfire, and under load it misfires. I'll try to post a video from my phone or i can email it to you so you can see. It's acting the same way it did when the Valve spring let loose. I can unplug the coils on the back four cylinders and not noticeably affect the Idle. But as soon as you unplug one of the front Four it falls on it's face.

I'm honestly at a loss never been this frustrated trouble shooting. I'm about to go drop it off at a shop... but wait i don't know any down here that I trust or personally know of their work qualityHAHA

Ideas? suggestions? anything is much appreciated!
 

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05 maggied CTS-V, 2017 NSX Whoo Hoo!
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8,810 Posts
its a very mild cam... effective but mild

thank you for the troubleshooting sheet
Good luck, but I would bet you are going to end up pulling the head.

The easiest way to tell if you bent a valve (without removing the head) is to remove the retainer and spring and see how easily the valve spins or if it hangs.

You have to be careful about piston location so you don't drop the valve into the cylinder.
 
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