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I have a '93 Acura Integra with automatic transmission. Ever since I got it some time ago the car has been vibrating a lot when stopped at a light, for example. The vibration is worse when in gear than in neutral, but it's present in both cases and slowly goes away as I drive and get closer to 2k rpm --- car idles close to 1k rpm. Also the problem is worse with a warm engine/transmission than when it is cold, presumably because at higher temperatures it idles at lower rpm.

Now, I noticed recently that the engine mounts were bad, so I replaced them. This only made the problem worse. Someone suggested I try injector cleaning fluid and that seemed to have made a difference, but only until I was done with that one tank of gas.

What could cause this behavior? Should I check the fuel filter or the injection system? Could this be a problem with the transmission and if so, what exactly could be going wrong?

[Edit] At some point when I was doing front axle work (one of the CV joints needed replaced, probably went bad due to the broken mounts) I noticed that there is some decent play in the differential. I understand some play is normal, but I'm also noticing sometimes, after I turn off the engine and release the brake the car will "shift" a few inches forward or backward before settling. Could this be related to the vibration?

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vlsd
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9 Answers9

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I've had this problem with my Honda accord 96 for an entire year and just figured out what was causing the vibration in idle mode. Changed mounts, cleaned air idle control valve and throttle body . Took it to a friend who in no time told me it was a BAD COIL not producing enough power. So check out your COILS

Roger P.
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If "injector cleaning" products helped but only lasted for one tank, I would try spraying Seafoam directly in at the throttle plate rather than putting an additive in your fuel. This should be a lot more effective at cleaning the injectors.

If that doesn't help, my best guess would be that the vibration is from unequal power from one or more of the cylinders for a reason other than the injector. A compression test would be the natural first step for checking this possibility, It's also possible that you have inconsistent belt tension as the engine rotates due to a bad idler pulley or bad bearings in the water pump, alternator, AC compressor, power steering pump, etc.

R.. GitHub STOP HELPING ICE
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Sounds like the Idle Air Control Valve and the Intake Manifold must be removed and cleaned.

The vibration is worse when in gear than in neutral

In gear there is a much greater load on the engine. Power is being transfered to the transmission and then to the wheels. This is going to cause the idle to drop a bit and this is where you'd feel the most vibration.

Also the problem is worse with a warm engine/transmission than when it is cold

When the engine is cold, the Air/Fuel mixture is set (by the ecu) to a rather rich condition. Giving you a higher idle while the engine control systems are helping the vehicle obtain operating temperature. When the vehicle is hot (operating temp) the mixture is greatly reduced, bringing it back to where it should be, causing the idle to drop and making the vibration much more noticable.

For the project you will need a few cans of carbuerator cleaner (three, maybe four) and a wiRemove the intake manifold and wire brush (one of the flexible ones that resemble a pipe cleaner). Remove the intake manifold and spray the inside and work the brush down each runner until the carb cleaner comes out clean(ish).

In the process of removing the intake manifold you will most likely end up breaking a few things like your PCV valve so you might want to pick one of these up as well while you're at the store grabbing supplies. Also, be sure to clean the Idle Air Control (IAC) while you have everything exposed.

NOTE: This repair is going to take some time and is only going to come out as good as you want it to. So please make sure you have a day where you can really tear into it. I promise you wont regret it.

As far as replacing the mounts goes. There are a ton of other symptoms other than vibration that come with broken motor/transmission mounts. Since I've never driven your car I can't really say if I would have even considered replacing them to solve the issue.

Also, please take note that you are driving an Inline 4. These motors are known to be rattle boxes. They put out a much greater / less smooth feeling than any V-style motor built.

cinelli
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You replaced the engine mounts? I would guess that since you had to change the engine mounts that there is a good chance that the tranny mounts may need to be changed as well...what is the drivetrain assembly like in that car since it is fwd, sometimes if the driveshaft in a rwd car is unbalanced it will cause the car to shake

Chris James Champeau
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I have also had this vibration and reducing rpm and shutdown problem in my Camry. After spending a lot of money and time on different mechanics, I found a solution. There is an air flow sensor that needs periodic cleaning with carb cleaner. After cleaning, the engine is smoother and normal.

Whenever the vibration returns, do the same, it's a regular maintenance item. I didn't replace the sensor, maybe this would be a permanent solution. The same issue occurred in my Belta 1.0 and I'm doing the same with it.

tlhIngan
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Nomi
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Based on your information, it appears your transmission is on it's way out. If your mounts were bad and the car was driven for a lengthy period of time, you were putting more stress on the tranny than usual. Being a FWD car with the tranny on the side, Horizontally opposed to the engine, it's verifiable when you say the car "shifts" when turning it off. This tells me that your torque converter is not fully releasing or your tranny gears/valves/springs are going if not bad already. I would drain the tranny fluid looking for metal debris and such, this will tell you that the tranny is grinding internally, not good. Or new fluid might lessen the effect, thus confirming it's your transmission. Moving on to the motor, if you're not seeing any smoke, white or black, your motor is probably fine. But still closely inspect your crank pulley as *This crankshaft is externally balanced by that pully.

Terrence LP
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Recently had a Ford Capri with a 3 litre V6 Essex engine which shook/vibrated badly at idle, done a compression test and 2 cylinders were nearly 40psi lower than the other 4 cylinders, took the engine out stripped it down and the rings on those cylinders were fried

Wayne B
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If you installed to non-OEM mounts, they will transmits normal engine vibration MUCH GREATER than you might believe, especially when they are cold and hard. The rear engine OEM mount, which manages the major vibrations, is fluid filled and vacuumed controlled (active/passive) to counteract vibration at idle (soft) and and at off-idle (firm). Non-OEM mounts do not have this feature and transmit all engine vibration all the time.

You can live with it or spend $$$$ to upgrade to OEM.

Don't ask me how I know...

steven
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I had a similar issue where my car (2012 Mercedes C250) would vibrate a lot whenever I stopped at a light but remained in gear. Once I changed the transmission mount, it went away. I would recommend changing the engine mounts as well, one of them went bad.

Merc
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