Hey y'all, I could use some help as I am having a frustrating issue with my 95 civic ex coupe: recently had thought that my surging idle woes were gone after I replaced my radiator thermostat and o2 sensor n did a whole flush/fill/bleed of the coolant. My CEL was giving me a primary o2 heater circuit code that went away immediately after that whole thing was done, and the idle surge went away for a while. It seemed to do it only when the car was cold at first, but had gotten worse before the maintenance above. This was just a couple months ago and I don't drive much - only a couple days a week sometimes.

Now the idle surge is back. It jogs between about 1000 and 1500 RPMs usually coming shortly after I start the car, but not immediately, maybe after I drive a half a block or so, and doesn't go away when it gets warmed up. It doesn't APPEAR to be a bubble in the coolant system since I've tried bleeding it several times now. Although I did notice that the coolant was low in the reservoir once after the radiator replacement, the level doesn't appear to have dropped again since then.

At one point after I had done the radiator/thermostat/o2 sensor change I got a single CEL that was either 22 or 21 (can't remember which - only that it was vtec related) but that went away on the next start and hasn't returned at all, so I thought it might be due to the weather we had, which was rather extreme cold or hot (can't remember which). But I am not getting any CEL now despite the surging idle problem.

Other than that, it appears to be running well - passed CA smog with flying colors. No power issues or anything, just the idle going wonky in Neutral at stops and such. (It's a manual 5 spd transmission)

Any ideas what could be the issue? What should I do next to troubleshoot?


I should mention I know f***all about cars. I'm a little 5'3 chick who is good at following instructions and handy enough to pull off some decent mechanical work as long as the instructions are good. So pictures and diagrams indicating what part is what when advising is especially appreciated, or at least what section to look it up in the service manuals (of which I have several).


It's bumming me out to have my victory over the last problem so short lived. But I guess it could be worse considering the car is 17 years old. I've had it since there were only 35 miles on her and literally drove it until the wheels (or rather ONE wheel) fell off of it, and I even have a youtube video of that part! ( ) Can't afford a new one just yet, so she is gonna have to go a little bit further , so thanks for any info or clues you can give me towards solving this.

 

Have you cleaned the IACV? Clogged IACV is a common idle surge cause for that generation of Civic. Here is a DIY:

https://www.hondacivicforum.com/foru...leaning-62836/

 

Don't forget the Fast Idle Throttle Valve (FITV). I had the same issue with my 95 Si. Cleaned my IACV and it got worse. Replaced IACV with a new one and it still surged. Replaced the FITV with a new one and all was well. It's located on the throttle body as well.

 

thank you, I will try these and report back. Hopefully one or the other will cure the issue!

 

Anything yet?

 

Got a little swamped, but just printed out the various diagrams and such that will help me learn what I'm doing before I set my car on fire or something dumb. ( I'm a measure thrice and cut once kind of gal when it comes to fooling with my car. This will be a new procedure, so I tend to go heavy on the research before attempting hands-on to prevent making matters worse AND we were out of carb cleaner so I needed to go get some supplies first. While I was at it, i picked up a new air filter and put that in too - a bunch of leaves and dog hair in there! Also, there is some debris which appears to be mouse turds around the throttle body area, but that would be a strange place for a mouse to be , I'd think... ) And now that I am finally ready to really get going on it, of course its raining buckets at the moment. I promise to check in if I find the culprit.


To my surprise, it seemed to go away for a bit the other day after a short jaunt to my moms which is only about 3 or 4 miles away. I am wondering what would be so intermittent and yet much more prevalent at start up

 

Mice in the intake box are very common. It usually shows up when the car will run, but barely go anywhere because there is a mouse nest blocking the airflow.