LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

Engine vibration

Old 03-28-2017, 05:25 PM
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Engine vibration

I have a 1996 convertible z28 I bought that been wrecked In the front end. I have fixed all the visual aspects but when I started it up I thought it was missing was thinking it was a miss so I changed all the firing components. But after that I figured out it was a bad vibration it will rattle the exhaust against the car. At low idle it just barely has a shake but from 2200 to 4800 you might as well be sitting in a massage chair it's bad but it smooths out at high idle right around 6000 rpm. I've had many camaro but I don't know where to even start cause all things I think it might be are expensive it is a 6 speed so clutch is possibility but don't think it's ever been changed any help would help my wallet.
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Old 03-28-2017, 05:51 PM
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Re: Engine vibration

since it was in a front end wreck...maybe the front damper/hub got bent

with engine running look at the front damper (some refer to it as balancer...but its not)

if there is any wobble you need to replace hub & damper

does the vibration happen if you just free rev the motor or only when "driving" the car?

or both?
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Old 03-28-2017, 08:33 PM
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Re: Engine vibration

Check for damaged engine mounts and trans mount. Check for incorrect pinion angle.
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Old 03-29-2017, 06:30 PM
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Re: Engine vibration

So it happens wether you are just sitting in the driveway or driving down the road in neutral or in gear with the clutch in or out. The hub is running normal wether at idle or at mid or high rpm is it possible that it is a miss the check engine light has obviously been unhooked cause it doesn't come on when I turn the key on. I have just never had a miss cause such a vibration
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Old 03-29-2017, 09:04 PM
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Re: Engine vibration

Even if someone disabled the SES light, you can still scan it. OBD-2 has misfire detection, and can tell you the number of misfires per individual cylinders (advanced parameters scanning required). Try an auto parts store, often they will scan for free. If they find a code, write down the SPECIFIC code(s) and post them here.

You can also get very inexpensive OBD-2 scanners, smart phone apps, etc.

You sure you have the plug wires in the correct sequence on the Optispark distributor? Did you inspect the Opti for damage from the front end crash? Did you change the Opti (obviously a "firing component")?
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Old 03-30-2017, 03:57 PM
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Re: Engine vibration

It was doing this before I changed anything and no I did not change the opti spark. Is it an option to pull the hub off and run the engine or will that be a bad idea I'm just true get to eliminate the options
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Old 03-30-2017, 03:59 PM
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Re: Engine vibration

And the opti appeared to be fine from a visual inspection
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Old 03-30-2017, 04:34 PM
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Re: Engine vibration

If you replaced the plug wires, and duplicated the existing wire routing, its possible it was incorrectly wired before and after.

The Opti cap and coil distribute 20,000+ volts. All it takes is a tiny crack to lose spark through external arcing. Observe the Opti and the wires with the engine running in a very dark location, looking for arcing. Lightly mist ignition parts with water.

The purpose of the crank pulley/damper is to control (”dampen") crankshaft "whip" resulting from combustion events. You can remove the pulley/damper without removing the crank hub. Might be a way to see if there is less vibration without the damper. Can't run it long without the alternator.

Courtesy of Shoebox

http://shbox.com/1/opti.jpg

http://shbox.com/ci/balancer_hub.jpg

Damper to hub is not an interference fit, but rust sometimes makes it necessary to use a 3-jaw puller.

http://shbox.com/1/pull_pulley.jpg
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Old 03-08-2019, 07:58 AM
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Re: Engine vibration

ever figure out anything on this??
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Old 03-08-2019, 07:57 PM
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Re: Engine vibration

Appears he read my last post, signed off a few minutes later and never came back. A shame that people never come back and tell us if they fixed the problem.

Try a private message, which will send him a notification, or send an email directly. Those options appear when you left click on his screen name.
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