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Discussion Starter · #1 ·
A few days ago I noticed that my cars idle was dropping down, once warmed up, to around 100 rpms, then it would rev back up to about 500....then drop back down to 100...an so on...and so on.

I took it to Lanier Honda to get some new vacuum hoses since some of them were leaking and could have been the culprit.

They also put on my cap and rotor button while replacing the hoses.

The tech showed me about 7 hoses with splits or cracks in them.

After leaving there the car idled smooth, except for the slight lopey cam idle, and was back to normal.

After the emissions test today I immediately noticed that it was acting up again. When this happens though there is no loss in performance just an idle problem.

I was thinking it might be a throttle position sensor or something along those lines, but there is no check engine light either.

Ideas anyone???

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Warren

93 Prelude VTEC N/A (lots of mods) [email protected]

00 Honda Accord SE (stock)
 

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Discussion Starter · #3 ·
Anyone else...?
 

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Well, I'm far far from an expert on this matter. But could it be something electrical that's going on and off that draws power?
 

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You might want you bleed your coolant system. If you have air bubbles, your engine can possibly fluctuate when idling.
 

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Discussion Starter · #7 ·
Ok....thanks for the suggestions.

I think I have it fixed now. I played with the fuel a little. As the temp has come up this week, and the fact that I set the pressure at lower elevation, the fuel is just a tad rich, causing the little hiccup at idle. After experimenting it has idled smooth again.

I also found a little change that has netted a noticable jump in power, going to adjust that a bit over the next day, and replace something. If it works out I will say what it was.
 

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VeeTec,

Definitely keep us updated.

I've noticed that my car has a tendency to do the same thing when I first stop at a stop light.

It'll drop to like 550 and then kickup to 750, but even at 750, the idle is a tad bit rough, not too bad.

I was going to try cleaning my K&N, checking my plugs and checking the IAC valve and see if any of that works.

Since I don't have any fuel system upgrades, I don't think I can tinker with that.

I also noticed that the rougher idle seems to only occur when the weather is cold (40 degrees and lower) and that warmer weather clears this up too. Can the temp have that much of an effect on this?

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2000 5-speed Prelude
Nighthawk Black Pearl
Momo Alumsport shift knob
Iceman Competition Intake
Mugen cat-back exhaust
Mugen headers
AEM underdrive pulleys
 

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chim 15,

I have this same problem, where i come to a quick stop at a light or stop sign, and the car feels like it is going to stall out. But the weather has been nice as of late, so the cold weather idle problem and check engine lights have disappeared.

In February, my car was diagnosed with a faulty O2 sensor that was tripping the check engine light. However, the light has not returned at all since the weather warmed up, so I think everything is ok. Does anyone still think i need to change the O2 sensor out? I have no warranty left so I have to swallow this cost.

Neel
 

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Discussion Starter · #10 ·
chim15,

I will keep you updated.

Neel,

I would replace it anyway because it might not be performing up to its potential causing a slight loss on power anyway, without the check engine light. That only comes on when it is failing.

They are fairly cheap and easy to replace.
 

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Neel,

I did just install my headers in the last two months, so I guess the O2 sensor leading into the cat could be going bad cause of handling during install, but I haven't thrown any codes. And after re-reading your post, I'm not sure if you're alluding to the fact that the O2 sensor would cause this idle fluctuation.

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2000 5-speed Prelude
Nighthawk Black Pearl
Momo Alumsport shift knob
Iceman Competition Intake
Mugen cat-back exhaust
Mugen headers
AEM underdrive pulleys
 

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<font face="Verdana, Arial" size="2">Originally posted by nmehta211:
chim 15,

I have this same problem, where i come to a quick stop at a light or stop sign, and the car feels like it is going to stall out. But the weather has been nice as of late, so the cold weather idle problem and check engine lights have disappeared.

In February, my car was diagnosed with a faulty O2 sensor that was tripping the check engine light. However, the light has not returned at all since the weather warmed up, so I think everything is ok. Does anyone still think i need to change the O2 sensor out? I have no warranty left so I have to swallow this cost.

Neel
</font>
Next time the CEL comes on be sure to check the code...are you sure it's the O2 sensor? If it hasn't come back i wouldn't worry about it. As for O2 sensors causing bad idles, my primary is shot and i'm waiting for the replacement, but in the meantime my idle is fine.
 
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