Today after work as I entered the freeway, I could hear a hissing noise. It was my intake, so I put my car into neutral and my idle was from 1k to 3k kept revving up and down.

I turn off the car and turn it back on and same thing happens. Having no choice but to drive I got home going 65-75 mph. As I got off the freeway and popped gear back into neutral I noticed the weird idle was gone.

What could have caused this ??

Temp was fine too
Odometer just broke into the 60k miles

Engine Mods:
AEM cold air intake
RBC air manifold
DC race header
GReddy Evo 2 catback

 

could be the tps sensor that usually casues jumpy idle

 

got any cel lights on....could also be mass air flow...best thing you could do is take it to a shop and have someone check all your sensors

 

Are you sure your coolant was full? Just because the temp was ok, doesn't mean the fluid wasn't low.

 

?




Honda's use a MAP sensor, not MAF.

Why would coolant affect the idle?


OP try cleaning out your IACV sensor and resetting the ECU to clear any codes, report back if the problem happens again.

 

I know that on most older Honda's, if the coolant was low the idle would fluctuate. A buddy of mine also had this happen to his 05 RSX-S. We just topped off the coolant and the floaty idle went away haha. I'm not sure why, or what exactly makes it fluctuate, but I know it can happen from experience. Also happened on my AE86, I had a bad radiator leak and I knew I needed to hurry and top it off if the idle got floaty

 

LOL that's interesting.

 

hissing could also be a vacume leak....that will cause a bouncing idle....where was your intake hissing?

 

I drove the car again about 6 miles, and it didn't do it all..
When I come to a stop for the first 5 minutes start the car
my idles goes up and down for about 2 seconds then lays at about .9k rpm

I have aem cai
rbc mani
dcrh
and greddy evo 2

Well if it was dirty wouldn't it do it often? I ran my car again and it didn't do it .. I will check though

I installed my rbc mani about 4 months ago spilled a good amount of coolant. didnt put more since i was still good. So why would it do it now if it was coolant ? right ?

I have a code due to a messed up 2nd o2 sensor so i need a tech

well the hissing was from my intake filter
I have an aem cai with fujita filter, and while the revving was happening the hissing was loud. after the drive home the hissing was the typical one

 

Could have let more air into the coolant system. That will raise temps a little and cause your to burn coolant off? Maybe just see if it's low. Again, my suggestion is based of a numerous experiences that I have had. It's prolly not the issue but I can assure it you that it can happen

 

I will check it out, I'm not driving the car so I don't do any damages to the motor.
I will take every ones advise.

Like I said it has been months since I installed my mani, so yesterdays weird idle can't be based on that ..

I hope I'm right lol

 

Weird, my antifreeze tank was empty. I filled up, my radiator did have antifreeze though.

 

That's the overflow reservoir. It was probably low since you didn't fill it up after installing the RBC lol I can't believe you didn't top off the coolant after installing that, ur goofy

 

and if the low coolant problem fixes your idle, I'm buying Josh a beer

 

YES!!!!!



... Whenever it happened to me, the coolant was really low though Radiator and all. I hope for you that it fixes your problem though!