Rough Idle?!?!

[Swonder67]

Hey guys, For a while now, my car has been idling rough. really rough whenever I am at a stop sign or a red light. But it only idles rough in drive, and reverse, not in park, or neutral. I reset the ecu, cuz i thought that maybe it was the air fuel mixture, but it still idles rough. any thoughts on why it's doin this. its kinda embarressing when i'm at a red light, and there's a car next to me, and my engine is rattling against the hood, know what I'm sayin?

[Darkwing]

this may sound very elementary, but when my car idled rough it was because the air filter in my car was bad. (It never hurts to look).

Other than that, I would need to know what kind of engine you have and any mods done to it to be of any further assistance. (which ain't much I admit)

[Swonder67]

I got a 97 DX. The only engine mods I have on my car are a generic short Ram intake and an exhaust, but the rough idle started happening before that.

[Dezoris]

Short rams and exausts, will hurt your low end, and can cause a rough idle, the exaust is the biggest culpret, because it reduces backpressure, which can cause rough idle. Try running 93 octane fuel and a bottle of fuel injector cleaner, the slick 50 product or valvoline. The best is to have the dealership hook it up to a machine that does it, this can help.
Also how are your spark plugs and wires? How about your distributor?
Was it changed at 30k miles? Also your throttle body should have been cleaned at that time.

[Swonder67]

I just got my 60,000 full Tune up. New plugs, wires and distributor cap. I tried the fuel injector cleaner, and it doesn't really work. The shaking really annoys me though. I need an oil change pretty soon, maybe that will smooth it out a little. Thanks for your help

[Dezoris]

No problem. ask most people reduced backpressure=rough idle.
Also the civic is notorious for a not so smooth idle, more mods mean worse idle. At idle when you turn on the AC do your RPMS kick up close to 1k RPMS? If so you are ok.

[Swonder67]

yeah, when I turn on the AC the engine does kick up the revs a bit

[Swonder67]

Also, another question. the way my exhaust hangs, one of the hangers is basically resting on part of the frame, and when I get that idling problem, the hanger rattles against the frame and I get this ping coming from the hanger. Does anyone know how to fix this?

[Dezoris]

You have metal hangers? Or are you talking about the bracket to mount hangers on? What exaust is it?

[Swonder67]

This is my exhaust. the part circled in yellow is the part that rattles against the frame.

[^YellowBandit^]

I think you can have that custom-bent so it wouldn't hit anything. :smoker:

[Swonder67]

Is there any other way to get rid of that rattling other then bending the hangers?

[cashman111]

Why don't you just stick something in between the hanger and the frame...or you can weld the metal to the frame or something of that sort to keep it from moving.

[Swonder67]

I tried that, but instead of the hanger banging on the frame, it banged on the part I stuck between it haha. Actually, I have a friend who works at a muffler shop, and he said that there was part of the hanger missing. It's a small pracket piece that you put on that actuallly pushes the hanger away from the frame. he said they cost about $10, so I'm gonna do that

[cashman111]

Sounds like a good, cheap fix. Good luck.