I have a 96 civic cx auto with 45k original. After 20 miles driven the engine will begin idling rough and lower than normal. The car has plenty of power through the driving range and if it stalls while at idle it starts right back up. There are no other noticeable problems and car runs great otherwise. The problem was also not corrected with a full tune-up.

 

All throttle body engines, and Hondas in particular suffer from grime buildup in the throttle plate and idle air control valve. See "troubleshooting idle probs." in the DIY section.

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good luck

 

The throttle body has zero carbon build up. The IACV also was very clean at the screen. As I stated in the original post the car had a tune up that included cleaning the inside of the throttle body (even though it did not need it). I had a 90' accord with a bad IACV and the civic problem is not similar to the accord's problem.

Keep in mind this car has 45k orig on it and the engine and trans look it. I thought the problem may have something to do with the fact it is a small engine with an auto trans. I have had similar issues with other non-honda cars from the late 80's to mid 90s that also had small engines and auto trans.

 

Idle speed control is managed by computer allowing more/less air into engine via the IACV. If idle speed is low (assuming other parts are OK), then causes are IACV failure (electrical/mechanical), blocked IACV passages, or dirty throttle plate. Did you look at back side of throttle plate and bore behind throttle plate, where grime accumulates?

good luck

 

The IACV screen is clean and the throttle body and throttle plate are so clean I could eat off off it if I needed too. There was and is zero build up in the throttle body and at the IACV screen. As I mentioned in my first reply I know about IACV problems. Trust me, it is not IACV or throttle body carbon build up. I wish it were.

 

Anybody check bulletins on this one. Their may be one involving the fuel injection. Has two injectors in the throttle body. Not sure without seeing it if this applies to your year etc. If it is I remember replacing the lower of the two injectors for fix. Sorry if Im not thinking of the correct year of bulletin.

 

How about maintenance items like spark plugs, distributor cap, rotor?

 

Plugs were replaced at 43k and showed normal wear, cap & rotor are fine, wires check out too. Problem was occuring both before and after these checks.