Engine vibration and metal noises

[Ryan S.]

I have been driving my D for nearly every day for the last 8 months without any issues. I just came back from a week long trip. I drove my D for a few miles without any issues on Friday. Yesterday evening, I started D and noticed an engine vibration. I figured it would go away once the engine gets warm. It really didn't go away even after engine warmed up. Engine continued to vibrate (cyclical type of vibration). When I accelerate from stop, vibration gets worse. It shudders at it goes from 0 to 15 miles. I also could hear a faint metal rattling noise from engine area. Once I reach the cruising speed, everything seems normal. I am not 100% sure but feels like I have less power now. I get a slightly more vibration when I put the transmission from P to D.

Other facts:
Idle is at normal, 700RPM and it doesn't fluctuate.
Air temperature here is at around 60-65F
Engine temp is within range
All fluid, including oil, transmission, and coolant are normal
Oil pressure is normal
Checked air filter and looks clean
No hissing sound from engine area.
Fuel injectors are secured and in place.
Oil filer cap is secured and in place

This car has
Automatic transmission
Dave's RPM relay
DMC integrated fuel pump with external check valve
Cold air intake

I would appreciate any advices or recommendations.
Thank you

http://www.youtube.com/embed/YhRjpBs2TM8

[vwdmc16]

Yeesh, that is a new sound. Maybe the flex plate of loose? Id like to come hear It in person. Don't recommend driving It until we fix It.

[Ryan S.]

Also, if I accelerate hard from the cruising speed, I could hear the metal rattling noise from engine.

[Jonathan]

From the video, I don't quite get the "feeling" of the vibration or to what extent it is doing so. Likely different in person I'd imagine.

One thought on a bit of shuddering/vibrating my car did in the past was related to a spark plug cap or two getting wet after a car wash. Not sure this is the same vibrating you're describing, but it is the first thing that came to mind. If that happened, get it dried out, confirm the connection is tight and sealed and reevaluate.

When the "metallic" sounding noise comes and goes in the video, it seems to me like it could be a fastener or bracket a bit loose. Check in the immediate vicinity to the engine and exhaust to see if all your nuts and bolts are tight. It seemed like it was centred around the muffler, but that could have just been because of where the camera was being held. There are 12 nuts to check on the rear fascia support strip (5 upper and 7 lower) that could be it. Or the cover near the latch mechanism or the lower engine cover latch itself. Perhaps also the brackets on the passenger side holding the cold/warm air intake duct as well as the coolant reservoir. Someone posted on here recently about taking their three way valve out and putting the cold air only duct in, but I don't remember if that was you. To me it sounds like something simple is loose outside or around the engine rather than something goofy going on inside it.

EDIT: sorry, just looked again at your list of car mods and see the cold air intake listed. Have a look there and see if something isn't snug.

[DMC5180]

Well, a several thoughts come to mind. This kinda sounds like something is contacting a Trailing arm shield or is not properly installed (clipped to the frame). Another possibility is a broken right side muffler heat shield bracket. I had that happen to me, the spot welds failed and the two parts would bounce against one another. If you still have the stock exhaust, there is a heat shield on the crossover pipe that could be rattling. Lastly you could have something failing with the flywheel Flex Plate.

[SS Spoiler]

Had strange rattle, traced to heat shield. Big ss hose clamp silenced it.

[WelmoedJ]

Racerx also mentions "loss of power".
So the rattling and this loss of power make on think more engine related than merely bracket problems.

Since it's an automatic the pressure regulator could have a damaged vacuum line.
You will not be able to hear that one hissing when over the engine, only when under the car.

Nevertheless that would not cause rattling.
Perhaps a defective (broken) transmission support bracket could cause that.
And has rupted the vac line to the pressure regulator?

[Ryan S.]

I checked all fasteners and they are all good and nothing is lose. I didn't hear any whistling sounds when I was under the car. Car is pretty dry. It has been in a garage for over a week and haven't washed it for over two weeks.
I will try to check spark plugs.
I always had some transmission fluid leaks and I did see leaked fluid around transmission area but the level was normal. Other than that, I didn't see anything unusual.
It is hard to see engine vibration from the video due to image stabilization system. Definitely it is vibrating.

[Ryan S.]

Clint came over and helped me check out my car. Clint thought that not all cylinders were working. Spark plugs were all firing up and looked ok. We test drove the car together and heard the rattling noise at full acceleration. Clint suspects fuel related issue. Per Clint's recommendation, I plan to take in my injectors for cleaning. Also replace spark plug wires and distributor.

[vwdmc16]

Right, all plugs looked clean and tan. All wires looked fair but with unknown age with cap, rotor and wires. When driving I heard a definite Knocking/pinging/detonating sound from a cylinder. Im leaning towards a dirty injector which also don't know the history of. New plug wires/cap/rotor and injector cleaning could go a long way to making it purr nicely.

The flex plate rattle noise was no evident anymore at idle.