Slight shaky idle

[myfavecoupe]

Should have asked what RPM it sits at. My car sometimes will idle at like 600rpm and it does shake a little bit like that. When it sits around 750, it's way less noticeable.

Have you adjusted your throttle cable at all in the past that would have caused it? I don't really see an issue though, to be honest.

I've taken throttle cable slack out about 5 years ago. Sometimes my idle does dip lower than what the video shows. It can go as low as the notch above the 0.

I don't remember if I've always felt the shake though, which is why I started this thread. I remember questioning if the car was on lol that's how "smooth" I guess I remember it to be.

With the a/c on and or headlights the idle is higher and notice the shaking less

 

[Wreckless Hype]

To elaborate a bit more on what I've noticed with the couple Civics I've had:

My 95, when I pulled the engine apart and rebuilt the top end, I had to put the throttle cable back on and it was a little loose. The idle sat really low and I could feel the whole car vibrating a little bit. I'm going to chock it up to the motor shaking from the really low RPMs and vibrating through the mounts, etc. When I got the throttle cable sorted out, it idled fine and I wouldn't really notice it anymore. I didn't have a tach, so I didn't know the exact numbers.

My 00 did this when my AASV was disconnected. You've got a 98 so no FIA system. But when my RPMs dipped low, I could visibly see the engine shaking a bit and obviously I could feel it in the car. Still now after everything with the FIA was put back to normal, the shift knob still vibrates. That's due to a bad trans mount, when I drive, the shifter moves back and forth when I accelerate, so that's a different issue.

 

[myfavecoupe]

I've had my transmission mount replaced before. Well the mount that faces the firewall. Pretty sure it's transmission one.

I tried idle relearn procedure yesterday but same result with the shaking. It is "less" noticeable with a/c on or headlights.

If I took the idle up a little with adjusting screw would it mess anything up? Right now it's pretty much where it should be within specs but does seem bit low. I adjusted best I could using factory tach and with iacv disconnected the idle was at the notch above the 0

 

[Wreckless Hype]

I wouldn't mess with the screw. I've never had to touch the screws on any of my throttle bodies. Turn the nut on the cable and tighten them down. You can always move it a hair and then move it back if needed.

 

[myfavecoupe]

I wouldn't mess with the screw. I've never had to touch the screws on any of my throttle bodies. Turn the nut on the cable and tighten them down. You can always move it a hair and then move it back if needed.

So you're saying tighten the throttle cable so it idles a little higher? Right now it's adjusted with the smallest amount of play (barely noticeable but enough to keep throttle plate closed)

 

[Wreckless Hype]

Before adjusting it, you can just pull the throttle arm a small amount and see if you can increase the idle a small amount and see if the motor evens out the shaking.

 

[myfavecoupe]

Ok. Just curious where does your car idle at? Is it higher than mine in the video I posted?

 

[Wreckless Hype]

When my car is warm, it sits around 750, 800, hair above where yours is at.

 

[myfavecoupe]

Hmm. Does the IAT sensor ever need to be cleaned? Wondering if it'd affect idle without throwing a code

 

[Wreckless Hype]

I've never cleaned mine.

 

[myfavecoupe]

Should I try some fuel injector cleaner? Kind of just throwing random ideas out that might help.

 

[Wreckless Hype]

If there is nothing wrong with your injectors or the fuel delivery, I wouldn't mess with it.

If you haven't done a full tune up and the car is due for one, I would hit that up. If you have a ton of miles and have never SeaFoamed your car, you could do that, but that's pretty much reaching. Beyond that, unless you engine troubles, I wouldn't mess with it too much.

 

[myfavecoupe]

I was just monitoring the idle with my ELM327 wifi Obd2 and at idle engine warmed up it'd fluctuate from 662-672 rpms.

Honda manual says it should be at 670 +/- 50. Would you say I'm in spec not sure if the slight fluctuations is normal? You can't see the fluctuations with car tach just looks steady

 

[Wreckless Hype]

I was just monitoring the idle with my ELM327 wifi Obd2 and at idle engine warmed up it'd fluctuate from 662-672 rpms.

Honda manual says it should be at 670 +/- 50. Would you say I'm in spec not sure if the slight fluctuations is normal? You can't see the fluctuations with car tach just looks steady

I doubt you'd notice 10 RPMs on your tach. Your idle is fine.

 

[myfavecoupe]

Cool. Think I was losing my mind a little on this lol. I blame it on slight OCD to have things as close to perfect as possible.

I'll just accept the small shake and move on hah

 

[Wreckless Hype]

On a car that's at least 14 years on, I'd likely accept a small shake as long as everything else was checked and came up clean.

 

[myfavecoupe]

Ok I didn't realize there was another motor mount at the lower front driver's side. Had to remove splash guard to see it.

Does it look bad enough to cause the shake? Has tiny tears here and there

 

[Wreckless Hype]

Where is this located? I have taken out lower mounts for the Power Steering, literally in pieces and put in new OEMs and felt absolutely no difference. Doesn't mean it shouldn't be replaced if it's bad. Push on it in the middle, if it falls apart, well, pretty self explanatory.

 

[myfavecoupe]

It's right next to the crankshaft. I think it's the mount you need to remove when replacing the a/c belt.

It's one of the torque mounts I believe it's called.

 

[Wreckless Hype]

Yep.

Here's what I pulled out:

And replaced:

No difference in vibration, etc.