ingnition/valvetrain maybe?

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Apr 21, 2015 | 11:14 AM

lwsprtn11

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Staging Lane

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ingnition/valvetrain maybe?

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

Ideas? suggestions?

Apr 21, 2015 | 02:02 PM

lwsprtn11

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Staging Lane

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awesome getting all the views in the world just waiting on the right technical fish to bite...

seriously i'm at a loss

Apr 21, 2015 | 02:10 PM

redbird555

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From: Pompano Beach FL

you had a broken valve spring any chance the piston kissed the valve and got bent a little? I highly doubt its unrelated but you could also have a coil on the way out.

Apr 21, 2015 | 02:14 PM

lwsprtn11

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Staging Lane

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Quote:

Originally Posted by redbird555

you had a broken valve spring any chance the piston kissed the valve and got bent a little? I highly doubt its unrelated but you could also have a coil on the way out.

i was thinking it was a valve but i did compression tests over and over. Also when changing the springs i changed that valve seal and the valve had free movement.

i'm still thinking bent valve. just trying to see if i might be missing anything before i pull the head.

ps thank you for the reply. Sometimes peoples ideas might be something over looked.

Apr 21, 2015 | 05:46 PM

RockinWs6

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Replaced with same springs? No misfire code and it won't rev over 3k? Interesting to say the least. Will it misfire in park? If will you should be able to find which cylinder OR maybe its all the cylinders?

Apr 23, 2015 | 09:51 AM

lwsprtn11

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Staging Lane

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Quote:

Originally Posted by RockinWs6

No 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.

Yes, 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 quality HAHA

Apr 23, 2015 | 11:31 PM

RockinWs6

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You couldn't of mixed the coil plugs? Was the spring actually broken enough to cause a misfire or is it possible it was misfiring and you discovered the valve spring and ASSUMED it was the cause? Any other things going on leading up to this?