Car vibrates at 800 RPM, no codes

Hello,

While researching this problem I came across this Technical Service Bulletin[TSB] for your vehicle's problem. You might want to contact your local dealership and talk to the service manager and see if you can get your vehicle fixed under warranty. Even if your vehicle's warranty is over, sometimes they can fix your vehicle and not charge you under customer locality. Please go through this TSB and get back to us with how everything turns out. I hope that this helps out.

Thanks,
Alex
2CarPros

It sounds more like the engine has vibration and not a runnability problem. Engine mounts can cause this. Can you raise the hood and rev the engine in neutral to see if the engine has excessive movement please?

Can you please shoot a quick video with your phone so we can see what's going on? That would be great. You can upload it here with your response.

Thanks for the video. it must be low compression on one cylinder. lets do a test by following this guide. Can you remove all spark plugs, keep them in order and check the color differences?

https://www.2carpros.com/articles/how-to-change-spark-plugs

and

https://www.2carpros.com/articles/how-to-test-engine-compression

Please run down this guide and report back.

That is a strange problem, did you do the compression test?

Hello again,

Do a dry compression test first. If and when you find the low cylinder than do a wet test on that cylinder. You do this by pouring a teaspoon full of clean engine oil down the spark plug hole and then rerunning the compression test. If the compression rises the piston rings are the cause of the low compression, if the compression stays the same then suspect a burnt valve or blown head gasket as the problem. I hope this helps and please let us know how everything turns out.

Thanks,
Alex
2CarPros

Hello again,

Well, It confirms that it is not a compression issue. Let's try this and see if we can identify a problem cylinder. Start your vehicle and go and unplug one electrical connector from a fuel injector. Listen to see if the tone of the engine changes. If it does than this is the problem cylinder. If not re-plug the electrical connector back on the fuel injector and move on to the next one. Get back to us with what you find out and we can go from there.

Thanks,
Alex
2CarPros

Hello again,

No. If the engine runs rougher when you unplug an injector than that cylinder is okay. Re plug the electrical connector back on the fuel injector and move to the next one. What we are looking for here is when you unplug the electrical connector on a fuel injector and the engine runs the same, no change. This will indicate the problem cylinder. Did any fuel injector not cause the engine to run rougher when it was unplugged?

Thanks,
Alex
2CarPros

Let's remove the serpentine belt and look at the harmonic balancer. I think it might have come apart. Also does the clutch work okay?

Lets remove the valve cover to see if you have a flat camshaft, this is a strange problem. This is usually a balance shaft problem but this engine does not have them. How did the harmonic balancer look? Also does the engine have okay power?

Yes it will, but I asked my buddy who works at the Chevrolet dealer he said these cars have issues with the engine mounts failing apart which can cause the vibration. Here are the instructions for replacement and inspection. Use a flashlight to inspect the harmonic balancer and look for anything shiny, rubber hanging out something like that. Check out the diagrams (below). Please let us know what happens.

Hi,

It could also be a engine flywheel that has excessive lateral runout, when combined with the extra mass of the clutch pressure plate and clutch driven plate, can produce a disturbance.
The clutch pressure plate and the engine flywheel are marked for proper indexing of the heavy-spot of one to the light-spot of the other. Improper indexing of the pressure plate to the flywheel can produce a disturbance.
An engine flywheel that is loose at the engine crankshaft or that is cracked, damaged and/or missing balance weights; and/or a clutch pressure plate and clutch driven plate that has loose springs, cracks, warpage, damage and/or missing balance weights †can produce a disturbance when their mass is combined. I'm attaching flywheel and clutch replacement below. Let us know if you need more information.

https://www.2carpros.com/articles/clutch-symptoms

https://www.2carpros.com/articles/how-to-replace-a-clutch

Thanks
Joe T.