Idle surge problem

[Kaneto]

Alright, this thing is starting to really bug me now.

92 Accord LX. When it's started up the RPM jumps from 1.5k to about 4k, and then drops. It jumps and drops continuously.

I've checked my vacuum lines and even tried spraying carb cleaner around in case one was leaking. I've replaced the Idle Air Controller. I've checked the coolant and made sure to bleed any air out of it.

What else could possibly be causing this idle problem?

[jazer80]

same problem here, but mine goes between a smaller increment. i looked around but couldn't find anything about it

[IH8SPM]

If you look at the penelum i think thats what it is called it the thing where the air intake attaches. Well on the opposite side of that there is a valve called the IAV idle ait valve. That is your culprit. If not then it has to the one in the middle. The reason this is happining is becuase anti freeze runs thr there and the sensor is clogged. Once the car heats to normal temp the revs are stay steady. View photo in my gallery.

[Kaneto]

Your photo shows the Idle Air Controller valve, which I already replaced. To the right of it is the Fast idle thermo valve, which I checked and it seems to be operating properly. Still having the same problem though.

[accordztech]

tps?

sometimes if ur idle is too high then it may do it.

clean out ur throttle body...the tps is in there i believe.

[IH8SPM]

Check your antifreeze. If not you may need to clean the one you think that is bad these parts seem to work and go bad together.

[excoupe23]

my 90 ex coupe is doing the same thing, idle is looping no matter if it is warm or cold and it happens sometimes and the engine feels like it is pulling me, I looked for vaccum leaks, cleaned throttle, changed pcv valve, cleaned out fast idle valve sensor and air boost valve. I checked antifreeze and I did fill to the top which helped a little but same prob what can it be ??????????help the new guy out. I also get a code 14 from auto tranny which I have to find out what it is but autozone's manual can't be right

[the_mad_scientist]

I've been having the same problem with my 90 EX coupe. I got the Haynes repair book from Autozone just the other day, and a code 14 is the Idle Air Control Valve (IAC). I checked on the price to replace it and it's in the area of $215. I haven't had a chance to look at it, but I'm hoping there might be a way to fix it without having to buy a new one. If anyone knows how this might be done, I would appreciate the help.

[hotghettoplayer1]

Originally Posted by IH8SPM

Check your antifreeze. If not you may need to clean the one you think that is bad these parts seem to work and go bad together.

is there a way to clean the sensor..im having the same problem with my 91 accord...the anifreeze is full...the timing is set..i dont hear any air leaks nor is the engine light on...this happends once in a while not all the time...somone told me a sensor, others told me to check antifreeze and air leaks...

[Truman1]

On older fuel injected Honda's (with out a IACV) a surge during fast idle can often be caused by a dirty fast idle valve, it can be taken apart and cleaned but replacement is usually better. It is that thing on the back of the intake manifold (On the front to the right of the IACV on 90+ accords) IACV's can also cause a surge but both these valves are on the expensive side to throw at this problem. Make SURE there is no vacuum leaks! A bad intake manifold gasket can also cause the IACV to "hunt" for the right idle speed warm or cold engine. A bad PCV can be all that is wrong as well but I have only seen the intake gaskets do this. Don't be fooled by lack of vacuum leaking sounds, there may not be any noticable. Try using carb spray or propane to see if idle speed changes when applied to the gasket and other suspected leak sites. One final thing, a real high surge (like the one going to 4k) can be a bad diaphram in that odd looking valve at the far right on the end of the manifold on 90 and later accords, it is for hot cranking to let in more air and will do really strange things if it's bad. I have only seen this on a purposely rigged car at a Honda Training Center. I hope this helps all you out there with Honda idle surges.