Ok, so I have a 98' Honda Accord, I have the dreaded idle surge that rev's between 1200-2000 rpm's. So here is what I have done to try to rectify the issue. I have replaced the EGR, IACV with OEM parts. I have searched high and low for a vacuum leak, I have the 505 code error for idle issues, I have made certain there is no air in the cooling system using using bob the car guys video, I also replaced an o-ring between the map sensor and the throttle body.
Also, I am aware that when the car is running and surging that if I unplug the map sensor briefly then plug it back in it's using a default program. This does temporarily cure the problem until the car is re-started.
I have searched online for hours to try to remedy this problem. Most have stated that the IACV was the problem. Well upon inspection of my car and having talked with the previous owner, it had recently been to the shop and the IACV was already replaced. When I took it off it was spotless on the inside, but whatever I replaced it anyway because I wasn't sure if they used OEM.
My car is a 98', 3.0 litre V6, automatic etc....
The throttle body was very clean. I looked online and saw that mentioning of plugging the 2 holes in the throttle body and listening to the cars reaction. So, upon plugging the top one, there was no change. Upon plugging the bottom one the car returned to an almost normal idle.

I have only thus far seen one other person with this issue as mine where the IACV wasn't the problem.
So to tell you a bit about me and my knowledge, I am a fix it myself if I can kinda guy, I have no real car knowledge other than if something break I learn how to fix it due to my lack of funds. Over the years I have owned prob 30 cars and they have had several issues.
So I know a little bit about everything, but I know everything about nothing!
Any help with this would be greatly appreciated, I'm new here and have searched the forums endlessly to try and find some resolve, none yet.

I hope I am posting in the right place...


I know some have mentioned around that it could be a manifold leak, intake leak etc... I am just trying to eliminate the easier stuff first. This car only has 51k orig. miles on it and I would really like to salvage it if possible.

 

Look in the DIY section for my thread on setting the base idle.