Hey guys, I've owned this used '03 Civic since last March and it has about 127k on it.

It has an intermittent performance issue. 70% of the time it is VERY lazy from idle right on up thru the RPM range. 30% it will pull the way it is supposed to and is actually fairly snappy. There is no "Check Engine" light on and no, it isn't just the difference btwn running the air and not running the air.....this is very noticeable.

I'm going to change the plugs because I doubt it has ever been done.
I would think that if a plug was partly fouled it would generate a code but I'll change 'em anyway, it can't hurt.

Any other ideas? Can someone explain how to clean the iacv (??) and throttle body? I'm pretty mechanical but haven't owned Honda's for long.....
Almost feels like it could be starving for fuel.....how often are fuel filters changed? I understand they only have one which is in the tank?

Thanks again,

JJF

 

Try changing the air filter. so your certain the check engine light works?

 

Yes, I've changed the air filter and yes, the check engine light does work.

I've been reading other posts and it sounds like this is a fairly common complaint.....

JJF

 

turn the a/c off?

 

Welcome to the EM2 haha, just kidding.

How does it idle from a cold start and when it gets warm?

Anything clogged in the exhaust piping?

 

Like you, I would start with the plugs. Use only those specified in the owner's manual. They were due at 110k miles, per my 2003 Civic's owner's manual

Consider replacing the front oxygen sensor. Even on the 01-05 Civics I am seeing reports that a code is not always thrown when the O2 sensor is failing.

Get only a Denso or NTK replacement sensor. Amazon typically has very good prices for these. I see now a new one goes for around $40 shipped total. Honda OEM sensors are always those that Honda gets from Denso or NGK, but marked up when purchased at the dealer.

 

The car seems to idle fine both when cold and hot, although on occasion it will stumble off idle and almost die.......but that is very rare. Usually it idles fine.

The power loss is substantial, like it's running on 3. I think it is running on all 4 though b/c the motor seems smooth enough........ but really lacks power.

I haven't changed the plugs yet but am going to as soon as I get off this computer....
If that doesn't fix it I am going to get software for my laptop and monitor things when the car is running.....

Also going to check EGR etc and see if I can determine if that front O2 sensor is on its way out...... I have been noticing a momentary dimming of the lights once in awhile while driving. Its got me wondering if the engine has a bad ground connection or something which is taking away from spark energy.........

Some members have been mentioning cleaning the iacv (??) & throttle body..... what's involved in that? ( I don't have any service info on this car......... )

Thanks for the tip Elle.....

JJF

 

Oh, and I really can't see it being a plugged exhaust.....this is an intermittent problem. A plugged exhaust would choke the motor constantly.......

Cheers,

JJF

 

Where is the throttle when this is happening?

If the problem is present at full throttle, it isn't the O2 sensor.

 

Idle Air Control Valve. It's located on the side of the throttle body, closest to the battery.

It's simply a matter of removing the air cleaner, a few bolts, a nut, some water bypass hoses, harness connector(s), throttle and cruise control cables, etc. etc.

The IACV is just screwed to the side. Take it off, spray it with some throttle body or carb cleaner, give the throttle body a good douching, then put it all back together.


You'll need to do the Idle Relearn since you'll be disconnecting sensors. It's easy.
Turn everything off. Wipers, radio, A/C, heat, rear defogger, etc etc. All of it.
With the car in Park or in Neutral, start it and hold it at 3,000 RPM until the radiator fan comes on, or until the coolant has reached 194 degrees.
Take your foot off the throttle and let it idle for five or six minutes.

 

Well, I changed the plugs last night. It does seem to run somewhat smoother and pulls slightly better. I don't think this is the complete cure though.

The plugs all looked white'ish which, to me, spells "too lean....." They were all about the same so i don't really think it is a faulty injector or anything. I'll look into checking out the O2 sensor as well as the IACV and TB. The O2 could certainly cause a lean condition which is what it feels like....

I'll keep ya posted, there's gotta be a few more Hp's out this little 4' banger !

JJF