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Car vibrates under acceleration from a stop

I have an 04 Acura RSX that begins to loudly vibrate under acceleration. I’ve read through many posts detailing a similar issue but they all mention the issue happening at high speeds. My issue only happens from a stop, low speeds, or uphill. If I very gently press the pedal in there is no vibrating/noise what-so-ever. It doesn’t do it in park or neutral or while I’m off the pedal. If I’m coasting at any speed there is no issue. It seems like the issue only comes when a large load is applied.

I’ve looked into these possible causes:
Engine Mounts - Didn’t think this would be the issue since it doesn’t vibrate in neutral?
Spark Plugs - Haven’t checked them yet, but same reasoning as above ^
CV Joints - Checked the boots and they’re undamaged. Suppose they could still be the issue but I didn’t think so since the rubber isn’t damaged and there’s no leaking grease.
Transmission - I originally thought my gears were grinding but I would guess that’s not the issue since the car drives fine under every condition except the ones mentioned.
Driveshaft/U-Joints - It’s FWD so that’s a no.
Wheels/Balancing - No problems at highway speed, so probably not.

All clues point me towards the CV Joints but I wanted to get some opinions before I go rip them out to check. I’m just unsure because like I mentioned the boots are in good condition. I would love to hear what you guys think, anything would be appreciated.

Have you tried swapping the front tires with the rears?

Tester

Most of the time there’s no vibration from bad mounts when in neutral unless they are extremely bad. engage parking bake, press firmly on brake pedal, put in drive, give a little gas. then do same for reverse. vibration? Could be motor mounts.

Many times bad plugs don’t miss until there is a load. a miss at 45 to 55 mph with slight acceleration is a common place for bad plugs to misfire

joints are often bad with boots intact. Is there play or slop when you turn and tug on shaft?

In both of those there is no load on the engine in neutral.

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If you can induce vibrations from a stop…by giving the car gas… You may be inducing a misfire or multiple misfires due to weak spark…from worn plugs or coil.

The more fuel you give the engine…the more you are trying to “drown” the Spark Plugs in fuel…if their spark is weak… you can extinguish this spark…and then have a misfire… which will vibe like crazy.

It wont happen under light load…light accel pedal…only higher load/more fuel conditions…

That’s where I’d be looking first. Plugs, Wires, Coil, the ignition system etc…

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Wow, thank you for the quick replies! I will be sure to check these first thing tomorrow and I’ll report back with what I find.

If you’re thinking sprark plugs, you may want to pick up a spark plug tester. They are fairly cheap I hear. Or idk what the other guys think, but maybe swap the plugs around. They could probably tell you which ones to move where.

If I am going to the trouble of removing a plug it will be replaced with a new one.

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Swapped out the spark plugs and the issue is still there. Glad I did it though, they looked like they needed to be replaced anyways.

Engine mounts appear to be fine, and the engine stays put when revved.

I jacked up the car and gave the cv joints another look. Like I mentioned the boots are in good condition with no leaking grease. I took the suggestion to give them a tug and the passenger side doesn’t move but the driver’s side felt like it was moving a few mm and made an audible clicking noise. Sounds like this is the issue then huh?

While it was jacked up did you manually rotate both front wheels checking for unusual play or noise? Assuming you hear no obvious clicking noise during slow speed turns, my guess — and this is a complete guess – is an inner CV joint problem. If a front wheel was not rigidly attached to the hub, that’s another possibility. Look for rust/corrosion on the surfaces where the wheel meets the hub.

in gear or in neutral ?

The spark plugs are only one item to be changed or checked in the search for the vibrations you describe (that MIGHT be misfire vibes). In the theory of the spark plugs being the cause…the plugs are only as good as the ignition coil…the plug wires or coil over plugs… whichever system you have etc… It would help immensely if I had your vehicle in front of me because I would be able to tell you exactly if it was a misfire or not…it is very distinct.

In fact you can actually induce a misfire yourself ! By leaving one spark plug UN-Plugged you can quickly teach yourself what a misfire feels like…rev the engine with one spark plug unplugged to really see… If it is identical to the vibration you are trying to describe to us, you can confirm or deny the condition to us… and we could advise much more accurately.

Might be a healthy exercise… since. Because if it is a misfire…changing the plugs is only one level of trying to solve that…

Then again… an 04’ Acura will DEFINITELY be posting Engine codes IF it were a misfire condition… Do you have any engine codes? Engine light illuminated? If so…those codes are diagnostic Gold…they are trying to tell you and us something… No codes? Then its not a misfire and I was incorrect… However that narrows things down insofar as what can cause vibes and not post a code…That can steer us toward a solution also.

We need to know.

No check engine light. I can check for residual codes tomorrow.

Also made an interesting discovery today. I can induce the vibrations from a standstill by using the parking brake method described previously. However, I CANNOT get the car to vibrate with the same method when in REVERSE.

That could mean there’s some sort of transmission problem. Manual or automatic? CVT?

The engine mounts are worn/hard and transmitting engine vibrations to the body under load.

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Auto, torque converter.

Makes sense to have the engine/transmission mounts checked first – by a pro — before assuming it’s something inside the transmission or torque converter.

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