Hi guys, hope I'm postin' this correctly!!! (Yes that is a big nOOb tatooted on my forehead) Anyhow, I have a '99 Civic EX with an irritating symptom... Ran a diagnostic and it came up with a P0505 idle control system malfunction, so as per the factory service manual I checked all the vacuum lines for leaks (actually ended up replacing all the vacuum lines and rechecking them for leaks) and I also replaced the idle air control valve with a brand new unit... BUT THAT ANNOYING LITTLE LIGHT KEEPS COMING BACK!!!! ARRRRRRGGGGGGHHHHHH!!!! Sorry, its just starting to really boil my oil... As you can probably expect with this code, my idle is a far cry from how it should be... It tends to hold a very high idle (about 1000 rpm) and occasionally has troubles with a lope in the idle (will bounce between 1000 and about 1250 rpm)... Any suggestions would be GREATLY appreciated!!! By me and the poor exterior of my Civic (I still maintain that it was hit by fist shaped hail that were miraculously the same size as my hand... Thats my story and I'm stickin' to it... ) Thanx again!!!

 

check also that the throttle isn't slightly open, in other words, unhook the cable from the throttle body to see if the cable isn't also sticking...ill assume you reset ecu...try the search

luck

 

I'll give that a try... thanx... and yes you assumed correctly I did reset the ecu

 

Correction... it is worse than I first stated!!! I'm idling at about 1250 rpm and lobing between 1250 and 1800 rpm... uuuggghhh!!!

 

yikes!!! Guess no one else has encountered this problem...

 

Is it an automatic?

 

Nope... Manual... I won't own an automatic...

 

A failing FITV (fast idle thermovalve) if equipped will give you these symptoms.

 

Might be the Intake manifold gasket or throttlebody gasket. Unlikely, but give it a shot.

 

Also try adjusting the idle screw on the TB, Mine had the same symptoms as yours, replaced the IACV / all vacuum lines - wasnt the problem.
Turned out to be the screw (mine is a 98 EX)

 

Thanks guys, but already covered all those bases also... No FITV equipped on the 99' d16y8... When replacing the vacuum lines i also replaced the intake manifold gasket and throttle body gasket... And I've tried correcting with the idle set screw on the throttle body with no luck... Now you guys see why this is getting so frustrating to me... Here's another weird aspect of it... From time to time the CIL will shut off and the car will run great, then about a day later it will come back on... I'm beginning to wonder if it isn't a possible problem with the ecu... Thats the last recommendation the factory service manual gives...

 

check the wiring and load test them, then think about the ecu

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 95DxSi-R2 &raquo;</TD></TR><TR><TD CLASS="quote">check the wiring and load test them, then think about the ecu</TD></TR></TABLE> I'll give it a try... see what happens...

 

Thanx for all the suggestions... And if anyone else has any additional input keep it coming... Thanx again!!!

 

that code simply means the idle speed is out of the ecu's target range. check the throttle plate itself to make sure its closing all the way. there has to be extra air coming from somewhere.

 

I believe its the Cold Air Idle Valve or CAIV. People have created block off plates to stop the problem. Its simply increases your idle when your car is cold to help it warm up faster and keep rpms high enough so oil is pumped thoroughly in your motor before you start driving it.

I believe you can buy a new one and replace it for the stock. Someone correct me if I'm wrong. But don't worrie, the crazy funky idle is very common among Hondas and doesn't really harm your car in any way.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Toyo Proxes RA-1 Rubber &raquo;</TD></TR><TR><TD CLASS="quote">I believe its the Cold Air Idle Valve or CAIV. People have created block off plates to stop the problem. Its simply increases your idle when your car is cold to help it warm up faster and keep rpms high enough so oil is pumped thoroughly in your motor before you start driving it.

I believe you can buy a new one and replace it for the stock. Someone correct me if I'm wrong. But don't worrie, the crazy funky idle is very common among Hondas and doesn't really harm your car in any way.</TD></TR></TABLE>

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by beanbandit &raquo;</TD></TR><TR><TD CLASS="quote"> Ran a diagnostic and it came up with a P0505 idle control system malfunction, so as per the factory service manual I checked all the vacuum lines for leaks (actually ended up replacing all the vacuum lines and rechecking them for leaks) and I also replaced the idle air control valve with a brand new unit... BUT THAT ANNOYING LITTLE LIGHT KEEPS COMING BACK!!!! ARRRRRRGGGGGGHHHHHH!!!! </TD></TR></TABLE>

 

Thanx guys!!! Runnerdown I checked the throttle body out thoroughly when I replaced the gasket so I'm pretty sure its not that, but thanx for the suggestion... Toyo Proxies RA-1 Rubber, you are definately right about this being a common problem... I have two buddys at work with Hondas waitin' for me to figure it out so I can help them with their similar problems... Think thats why this is gettin' to me so much... Hate to have a problem that proves this difficult to solve!!! It makes it hard for me to maintain my calm and pleasant demeanor!!! (is that the scent of sarcasm... sniff sniff... ) But keep the suggestions coming guys!!! I'll try anything to see if I can get this worked out... Thanx again!!!

 

You know... I should probably be out in the garage workin' on my problem instead in here postin' messages... bein' lazy today

 

howdy... i'll try to up this one more time to see if i can glean some more input...