Stevo F

We bought my sisters 2001 Accord for my son 4 years ago and the idle seems to have gradually gotten a little rougher over time. Engine runs smooth as glass above 1000 RPM, but the car shakes a bit below that (especially through the steering wheel). Idle speed is normal (about 750 RPM). Not a misfire, more of a steady vibration.

My mechanic suggested cleaning the throttle body or maybe the IACV. I tried putting some Seafoam through the throttle body, but no improvement. The IACV looks like a bear to get to because of where it's mounted on the throttle body.

I replaced the distributor cap, rotor, plugs, and plug wires last year but it made no difference in the idle.

So is my mechanic likely right or could it be a bad motor mount?

user456101

Almost always the idle air control valve or the throttle body. Check out Scotty Kilmer's YouTube video "How to fix a car that idles poorly" If it is a 6 cylinder then the EGR may also be the culprit. You need to watch a video on that one because it is really about cleaning out the EGR passages in the intake, not cleaning the EGR valve itself. There is a chance that the rear engine mount, the one closest to the firewall, has a problem. There is a vacuum line that goes to this mount that is supposed to make it vibrate less at idle. You can check to see if the vacuum line has come undone and/or that there is vacuum present on the line leading into the mount. You may need to access a service manual to understand what I am talking about on the mount and how to test it.

holmesnmanny

Normally the iacv has a metal mesh filter on it that you might need to clean out. It could be junked up with carbon. Just remove it and gently clean the filter, removing all debris.

Stevo F

Actually this is the 2.3 liter 4 cylinder. It looks like the IACV is right between the throttle body and firewall- hard to even see it let alone unbolt it- is there a trick to getting to it on this engine?

holmesnmanny

Perhaps extensions and universal swivels/joints.

calcord2000

Stevo F, I know what you mean about the location of the IACV. The IACV is tough to remove but it can be done, trust me. Here are some tips.
First, use a small mechanics mirror to see where the bolts are located, I believe there are two. Disconnect the wire connector leading to the IACV. It is held on by a clip. There are two small coolant hoses attached to the IACV. Those have to be wiggled out. You really have to reach back there to loosen the hose clips and then the hoses. Use a small ratchet to unscrew the two bolts that keep the IACV in place. You have to be extremely patient when removing them.

It helps if you remove the air intake tube that connects to the throttle body. Or you can throw an old blanket over it. That way when you are reaching behind the throttle body, you don't have car parts digging into your stomach or chest.

I can confirm the rear engine mount does have vacuum line. I used an Anchor engine mount replacement. I couldn't afford the Honda version. This is a two man job by the way. The engine must be lifted a bit in order to remove the rear mount.