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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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  • Have you solved the vibrating/shaking problem? Hope you dont mind sharing..thanks:)
    – user9272
    Commented Jan 30, 2015 at 18:20
  • @burn I have not. I have been super busy with a thesis and other broken things on the car. My current three candidates are PCV valve, injectors and intake manifold, in that order.
    – vlsd
    Commented Jan 30, 2015 at 20:38
  • I have the same problem as yours. I will update if I ever manage to find a solution. And hopefully you do too. Thanks
    – user9272
    Commented Jan 31, 2015 at 1:32
  • Ever find the problem?
    – Robert S. Barnes
    Commented Sep 21, 2015 at 9:25
  • @RobertS.Barnes Unforturnately, I did not. Had to sell the car for a move, and that was that...
    – vlsd
    Commented Sep 23, 2015 at 15:33

9 Answers 9

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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

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  • Even though I don't have the care anymore, this sounds highly plausible (and also something I did not check), if for no other reason that it's a car from the same manufacturer and decade, so they probably share designs. When you mean a a bad coil, do you mean the coil in the distributor?
    – vlsd
    Commented Oct 27, 2015 at 20:09
  • How did he diagnose that the coil was bad?
    – Robert S. Barnes
    Commented Dec 10, 2015 at 18:04
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    @RobertS.Barnes most coils have their nominal resistance printed on them; you can use a multimeter to determine the actual resistance of the coil, and if it's way off it means something is wrong and the coil busted; I think there are other ways coils can go bad, but this is the most common...
    – vlsd
    Commented Feb 23, 2016 at 0:08
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+50

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.

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  • Great suggestions! I will try the seafoam shortly and come back with results. If it is a pulley or bad bearings (the car is pretty old, bad bearings everywhere) how would I check that?
    – vlsd
    Commented Apr 29, 2013 at 15:12
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    The most reliable way is probably to take the belts off and try to rock the pulley side-to-side and up/down and see if it has any play in it. But for stuff on the timing belt that may be more work than you want to do if you don't have a good reason to believe it's the problem. You can probably get a good idea if the pulley is wobbling just by watching it move with the engine running.
    – R.. GitHub STOP HELPING ICE
    Commented Apr 29, 2013 at 15:29
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    By the way, before you put any more effort into checking the pulleys than some casual inspection, you should probably do the compression test first, at least as long as the spark plugs are easily accessible. Unfortunately that's probably more likely to be the source of the problem. But yes, do the seafoam first, because it's easy and lots of the time it fixes what's wrong. :-)
    – R.. GitHub STOP HELPING ICE
    Commented Apr 29, 2013 at 15:32
  • Seafoam didn't make a dent. Compression test is next.
    – vlsd
    Commented May 4, 2013 at 23:21
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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.

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  • Thanks for the thorough answer. My gut tells me that everything you say is correct and this is what I must do. The loose motor mounts were grinding down one of my CV joints so I had to replace both those things regardless of the current rattle.
    – vlsd
    Commented May 1, 2013 at 16:00
  • I did this except I only removed the throttle head and all the other valves and cleaned them. I didn't take out the whole intake manifold as that would have required draining my coolant and a lot more time than I had. Anyway, this cleaning and spraying carb cleaner straight into the intake manifold did not have any effect on the vibration, which makes me think this is the wrong path.
    – vlsd
    Commented May 4, 2013 at 23:20
  • was the idle air control valve cleaned? and PCV valve cleaned / Replaced? The Idle Air Control Valve when removed will spill coolant it's located on the back side of the intake manifold and has a few 12mm bolts holding it on. P.S. spraying carb cleaner direclty into the intake is not the same as removing it and cleaning it.
    – cinelli
    Commented Jun 2, 2013 at 8:06
  • Yes I removed and thoroughly cleaned both those valves. I did not remove the whole intake manifold as the space is rather tight, there are a lot of things in the way and it would require me to drain and replace the coolant, something I wasn't prepared to do just yet. The problem could still be somewhere down in the intake and/or one of the injectors.
    – vlsd
    Commented Jun 3, 2013 at 16:58
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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

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    by motor mounts i meant all four mounts that keep the engine and the transmission in place, so including the transmission mount. yeah, the car is fwd and the engine/transmission are mounted parallel to the axle.
    – vlsd
    Commented Oct 6, 2012 at 18:14
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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.

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  • I did change the tranny fluid not long ago and there wasn't any sign of metal shavings or anything else. New fluid also didn't impact the effect. I'll check the pulley, thanks!
    – vlsd
    Commented Apr 30, 2013 at 16:32
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    I want to add also look at your ignition coil for cracking. Stumbling could be your coil arcing to the block. This would explain it getting worse as the motor heats up.
    – Terrence LP
    Commented May 1, 2013 at 13:56
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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.

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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

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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...

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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.

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