RPM is high but gradually goes down...

[rna800]

Guys, I need your opinion on what seems to be the problem in this.

About 2 days ago I noticed when I started my car, the RPM shoots up to 1500 and it stays at 1300. While it was traffic, I noticed that it gradually goes down until it reached the line in between 700 and 800 while idling. Added to the oddity, even if I am traveling at around 40 to 60 kph, the rpm is passing the 2000 mark.

Today, I really observed and timed it and this is what I came up with:

1st start: RPM * 1500 but it will go down to 1300
* 1 min 30 secs: RPM * 1000
* 2 mins 10 secs: RPM * 900
* 3 mins 40 secs: RPM * 800
* 5 mins onwards: RPM is in between 700 and 800

If it's in between the 700 and 800 mark and I tap the accelerator pedal about let's say 2 to 3 inches, it will shoot up to 1600.

At first it's the idler but if it slowly goes down, I don't think that's the problem. The engine is as quiet as before and there are no signs or signals telling me that the engine has a problem.

I called Honda Fairview since they were the one who replaced the RACV (Rotary Air Control Valve) about two to three weeks ago. They told me maybe an adjustment is needed but there is no need for me to be alarmed... hopefully.

So guys, maybe you could help me a little bit. Thanks!

[niky]

Most likely it's just the control valve needs adjustment.

[rna800]

Thanks! What's odd is I had that replaced about 2 weeks ago and it's just now that it happened. I will just have them checked it.

[niky]

Yeah, it happens... could be you just need your hoses and fittings checked, and the valve adjusted... possibly the "cold idle" is tuned a bit too high. Not a big deal if it doesn't stick open when it's hot. If it does, then that's a problem.

[v6dreamer]

Does your car idle rough or the speed cycle up and down. You probably have a bad idle air control valve. The purpose of the idle air control valve is to keep the engine’s idle smooth. The engine’s computer gives the idle air control valve the feedback it needs to hold a constant rpm. The idle will be around 1000 rpm’s or more ( like your's) when not in gear and around 800 rpm’s in gear. Check those hoses also for abnormality, like crack or loose.

Bring your car back to honda still in warranty, something has done not right. Could it be a bad parts when they changed your idle air control valve.

[rna800]

Does your car idle rough or the speed cycle up and down. You probably have a bad idle air control valve. The purpose of the idle air control valve is to keep the engine’s idle smooth. The engine’s computer gives the idle air control valve the feedback it needs to hold a constant rpm. The idle will be around 1000 rpm’s or more ( like your's) when not in gear and around 800 rpm’s in gear. Check those hoses also for abnormality, like crack or loose.

Bring your car back to honda still in warranty, something has done not right. Could it be a bad parts when they changed your idle air control valve.

I don't notice any rough idling. The sound of the engine is as smooth as ever and it runs smoothly. I don't even hear it roar but when I look at the rpm, it's really high and it's all over the place especially when I reduce speed and step on the gas pedal again since just a tap would really make it shoot up.

[v6dreamer]

I don't notice any rough idling. The sound of the engine is as smooth as ever and it runs smoothly. I don't even hear it roar but when I look at the rpm, it's really high and it's all over the place especially when I reduce speed and step on the gas pedal again since just a tap would really make it shoot up.

Have you ever notice of losing accelaration power in your car from standstill acceleration or even passing other car on the freeway that whenever you step the gas pedal your RPM shoot up?

[rna800]

No sir, not that I can recall losing acceleration. The engine runs smoothly whether idling, moving from a standstill or cruising. I don't even hear any strain in the engine. It's really smooth. It's just that when I look at the rpm, it's above 2k with speeds around 40 to 60. I don't have any idea when this started since I noticed this about 2 to 3 days ago when the first time I started the engine I looked at the rpm and to my surprise I saw that it's above 1k which I knew immediately that it's not normal.

[v6dreamer]

There's a few different things that can cause your problems, fortunately most are easy to check kailangan lang ng tiyaga.

First: Check your throttle body for carbon build up around the throttle valve causing it to stick open. If carbon found, crank engine and and stray carb cleaner down throttle body to break up carbon. You will know when problem is fixed, it will drop to normal. You may notice the car run a little ruff at first, but once the carb runs out of system it will idle normal again.

2nd: Check your throttle Cable. I've only seen this a few times, but the throttle cable will bind or come partially off the throttle lever, causing throttle valve to open. If you see a problem with throttle cable, replace if binding, or adjust if cable is partially off throttle lever.

3rd: You will need to take your car to a shop to check and see if the computer is comanding such a high idle. If this is the case you will need to replace the ECU (Electronic Control Unit).

4. Recently, honda change the IACV in your car, so I would strike on that but I wont totally ignore it since never happened before this problem till recently.

Usually one of these things will be your problem on a honda. Good luck and hope this helps!

[rna800]

Thank you so much, sir, on your detailed information. Since I am not mechanically gifted unlike you and the other tsikoteers here, which I envy so much and hoping that I could also become someday, I don't think I could do all of those. It might worsen the problem if I touch the engine.hehe But at least when I bring it to the auto shop, at least I have an idea on its causes and I could also give advises on what's causing it(thanks to sir v6dreamer.hehe)

Sir, is the IACV (Idle Air Control Valve) the same with the RACV (Rotary Air Control Valve)? Coz it's the RACV that they replaced.

[v6dreamer]

3-wire Idle Air Control Valve IACV or Electronic Air Control Valve EACV . It is officially termed as Valve Set Rotary Air Control (pwede rin Rotary Air Control Valve), made by Denso in Japan. It can be easily installed on several 96-00 Honda Civic OBD2 D-series throttle bodies, VTEC or non-VTEC, manual transmission or automatic transmission. It is installed below (horizontal draft-type) or at the side (vertical draft-type) of the throttle body.

[comecum]

Try checking/cleaning your air filter element, baka madumi lang, not enough air is coming in.

[rna800]

I just went to Honda dealer today to have that high RPM checked. After 7 hrs in the lounge, they told me that they checked everything and everything was perfect except for a little adjustment in the RACV. Before they handed me the car, the SA explained that the every start, the RPM will reach above 1k but will eventually go down. He said that's normal which I don't really buy. I have other cars and none of them is like that. Every start, they are always below 1k regardless if it's the first start or morning or any time of the day.

Then as I was driving on the way home, I was observing how the RPM and I feel that nothing has changed except before, it takes more than a minute for it to drop to 1k and 5 mins for it to totally reach 800, but now, when I started the engine in Honda, it went to above 1k (just above the 1k line) and after about 3 seconds, it dropped to 800. It was faster. Back to when I was road; I was observing and I felt that the car is a little bit choked(it feels like the car is so heavy for its engine) and I still noticed that it needs a lot of RPM for a little speed but eventually it will go down as it reaches its range. Like from 1st to 2nd gear, at normal driving and with a light foot, the RPM would still go as high as 2k but it will eventually drop. I felt like I was driving a sports car, minus the "sports", with how the RPM moves.hehe I think if an exactly the same car (all stock) is beside me and decides to give a little adrenalin rush, I feel that I will get left behind given this kind of engine condition.

So they have already checked it and it's still the same, what do you think is wrong with it? Do you think that it's still normal? Honestly, I don't buy what the SA told me that it's already fixed. My concern is with a high RPM, I feel that the engine is more strained that would probably cause overheating, etc, and of course, my FC will be affected too. This weekend, I am planning to have it checked with my trusted mechanic just to have a second opinion. Maybe you're right sir comecum, but I believe they have already done that?(I guess... hopefully)

[niky]

It's normal for idle to stay high when its cold... especially for newer models that need to warm up quickly due to emissions regulations.

If it feels slightly choked, it's because your idle is now lower, so throttle response and tip-off power are lower. That's a side effect of high idling...the car will feel much more responsive because you need less gas pedal movement to get the car to go.

[rna800]

It's normal for idle to stay high when its cold... especially for newer models that need to warm up quickly due to emissions regulations.

If it feels slightly choked, it's because your idle is now lower, so throttle response and tip-off power are lower. That's a side effect of high idling...the car will feel much more responsive because you need less gas pedal movement to get the car to go.

The thing is with mine, after the idling adjustment, every time I start the engine, it will always go above 1k and after about 3 seconds, it will go down to 800. It's always like that every time I start regardless if it ran for an hour and I turn off the engine and restart or it's my first time to start it. And just like the old problem, just a slight tap on the gas pedal, the RPM shoots up as high as 1600 and goes down to 800 and while cruising at around 80, it's a line shy of 3k. Also from a standstill, from 1st to 2nd gear, it could even go as high as 2k just to get a momentum considering that I always drive like that. This problem arose when they replaced the RACV. It's just driving me nuts seeing the RPM needle swinging up and down like a mad man weaving through traffic.

I am going to visit my trusted auto shop today since the boss there drives the same car as mine so it's easier to compare and perhaps fix what's causing it.

[niky]

Okay... good luck!