hello and thank you all in advance that try to help.

I have a 99 Honda Civic EX 5 speed, for about the past 3 months it has been tossing the P0505 code "Idle Air System Malfunction" at random intervals in regards to mileage and amount of time since I have "thought" I resolved the issue. Of course it acts like it is rabbiting and idling randomly between 800-1500 rpm.

I have taken off the IACV and cleaned it thoroughly and replaced it still getting the code after it has been cleared when the part was replaced and also when i cleaned it, I have a modified short ram intake and have replaced the TPS sensor as well.

I have checked for a vaccuum systems leak thoroughly and it has none, my next step to my best knowledge is replacing the Throttle Body, which through Honda according to them this is their cheapest throttle body at a whopping 400 dollars before tax.

I have checked with local parts distributors such as o'reilly's, advanced auto parts, and autozone. They all can get me either Holly or Edelbrock for about 365.00 USD The Holly makes you use stock components such as your TPS and MAFS and costs about 310.00 USD.

The Edelbrock comes with a TPS designed for the car and has a 90mm Port with an adapter for my intake to connect to. Straight from Edelbrock cost to me w/ shipping and handling is about 340.00 USD to my doorstep.

I was wondering if there is something I am overlooking before I spend this much on my charge card and if there is an opinion of one or the other to go with as I have heard of both manufacturers and feel that it would be better to upgrade now since I plan to do more in the future instead of going with standard OEM Honda throttle body.

Also, for the record I have tried adjusting my throttle cable while idled to lower it but doesn't seem to affect it as well as back the screw out of the air port on the backside of the throttle body to have it stop the error code for 3-6 days then the code comes back which is what is leading me to believe its the throttle body starting to get clogged even though it has been cleaned.

Any input or thoughts in regards to this matter are greatly appreciated and I will try my best to answer any other questions.

 

welcome to the forum. Wondering if you checked the map sensor.

 

yes that has been cleaned as well, but one thing I found out yesterday talking to a mechanic friend of mine while at advance autoparts was that with these particular cars if the overflow tank of the coolant which is used to help cool the car not just overflow excess coolant while running is empty it will put air bubbles into the coolant and mess with the air of the idle air system which he said sounded like was the reason for the error code this time in my case.

I checked and sure enough the tank was just about bone dry. filled it up and checking it over the next day or 2 is the process to make sure it stays filled. I reset the code and so far so good but last time I did work on it, it stayed off for almost a month so now we wait and see.

Thanks for your input.