When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I'm no stranger to this issue and am well versed in the diagnosis procedures. My 1999 Civic (all stock) had this issue a while back and I solved it by replacing the air assist solenoid (part #24 on the diagram). That seemed to solve it. It's weird. Sometimes I'll get a surging idle out of nowhere.
What, if anything, could cause this issue to arise sporadically? It goes away on its own over time it seems. Worth noting: it's sub zero temps here and it's the 1st time of the year we've had such cold weather, and naturally, that's when the idle surging arose again.
I can't figure out for the life of me what could cause this issue to appear again. I feel there's nothing I've missed before (bled coolant, block tested=no exhaust gasses in coolant, no air or vacuum leaks, idle relearn, etc)
I feel it's needs an idle relearn procedure performed, but done so with specialized Honda software or such. I feel the procedure outlined in the shop manuals isn't sufficient enough.
I'm lost.
The IACV could be sticking slightly open when you cold start the car. That's why the IACV has coolant routed to it - to allow the warm coolant to heat up the IACV and prevent it from freezing/sticking. If you're surging idle goes away once the car is fully warmed, this could be the cause (a non-issue).
The IACV could be sticking slightly open when you cold start the car. That's why the IACV has coolant routed to it - to allow the warm coolant to heat up the IACV and prevent it from freezing/sticking. If you're surging idle goes away once the car is fully warmed, this could be the cause (a non-issue).
Thank you for your reply. I installed a new IACV a while back (sadly, it was a cheaper ebay unit) and the surging went away. At that time, I also installed a new (genuine Honda) air bypass solenoid. My surging went away(after last post) for several days after an idle relearn procedure. Today however (Temps at 6°F) it has returned. Seems it COULD be related to outside temps, as the last time this happened it was this cold out. Could this be an intake temperature sensor?
I just can't figure it out. It's so odd that the surging will return after all this time (about 1 year). I feel it's nothing mechanical, but perhaps something else.
Thank you for your reply. I installed a new IACV a while back (sadly, it was a cheaper ebay unit) and the surging went away. At that time, I also installed a new (genuine Honda) air bypass solenoid. My surging went away(after last post) for several days after an idle relearn procedure. Today however (Temps at 6°F) it has returned. Seems it COULD be related to outside temps, as the last time this happened it was this cold out. Could this be an intake temperature sensor?
I just can't figure it out. It's so odd that the surging will return after all this time (about 1 year). I feel it's nothing mechanical, but perhaps something else.
The IACV can get dirty and clogged best to check and clean it with brake parts cleaner. My Ebay IACV is starting to stick again after about a year..
The IACV can get dirty and clogged best to check and clean it with brake parts cleaner. My Ebay IACV is starting to stick again after about a year..
This is EXACTLY what I'm thinking. I replaced my OEM one with a cheap ebay unit a while back. I'm now thinking this cheap unit is failing. Gonna get a genuine Honda one
SURGING IDLE /HUNTING IDLE
