eaf

Hi,

Smth just happened to my 99 V6 Accord after I didn't drive it for 10 days or so.

Immediately after I start the engine, RPM jumps to 2000, and then after a few seconds it continues oscillating between 900 and 1500 every second or so. The oscillations do not stop when the engine warms up: RPM keeps going up and down as long as the transmission is either in "P" or "N" as if I was cranking it with the gas pedal.

The car is still driveable. In fact, on the highway, it feels the same as before, I do not feel, see or hear any oscillations, but traffic lights became a real nightmare: the RPM stays high at 1300, so I really have to step on the brakes to prevent the car from moving.

Once "Check Engine" light came on on a traffic light. I reset it by disconnecting the battery, and it didn't come on ever since, so I successfully drove the car home for 50 miles or so.

Did someone experience anything like this? What could be the problem?

Thanks!

Cytoplasm

i just had this EXACT problem this morning... how strange... any ideas would be awesome

eaf

I collected more info.

Today the "check engine" light came on again, and I got the code this time. It's P0505, which decodes as "Idle Air Control System". No clue whether it's FITV, IACV or the hoses.

To make things worse, I cannot even find where the FITV is. The tubing scheme under the hood has an EVAP purge value in it. Though the valve is connected to the intake by a hose, it's not attached to the intake: it stands aside. Does anybody have the intake diagram for 3.0L V6 engine that would show FITV and IACV?

Other related things that I got from the computer are the:

Intake Manifold Pressure: (11.5 in.hg.)
Abs Throttle Position: 9.8%
Fuel System1 Status: continuously cycling between "closed loop" and "open loop, driving" while the transmission is in the "P".

Any clues?

nickhans

hi there, i just saw your message and i have the same problem with my 1991 honda accord. what it is, is your EGR valve. it isnt circulating the recycled exaust through the EGR valve. it is quite costly repair, but easy. im not sure that it is it but hondas act alike.

ziich2

This problem just started happening to my 99 Si last night. I've been doing searches on HT to find a solution, but I haven't found any helpful answers.

Ever since I bought this car 6 months ago the check engine light was on, but I always assumed that it was because of a bad/missing O2 sensor (gutted catalytic converter). I've never bothered to check the code.

Yesterday while driving back from class, the CEL would start blinking at idle at stoplights, but as soon as I started moving, it went back to being constantly on ("normal").

I did an oil change afterwards and had a few VTEC runs (for fun and because the weather was cool). Ever since then, the revs have been fluctuating from 900-1800.

After reading some posts on HT, I decided to have a look at my IACV, I cleaned out some of the carbon build up, reset the ECU and that calmed it down a bit, but it still idles high 1100-1300.

I have another class to go to now, I'm going to check the CEL codes when I get home or just hope the problem goes away on it's own..

jdeemseerx

ok forget anything wit the egr valve, if it were that than the computer wouldnt have had the iacv code.. look on your intake manifold you will see too long cylinder like components,,your fast idle thermo valve and your idle air control valve,..sounds to me like your iacv could be clogged up.. there is a plug going to it and two coolant lines..take everything off of it..remove it from the i.m. and clean the screen inside it with carb cleaner..be sure not to ruin the gasket or your probably better off replacing it..put it back on, tighten to spec so no leaks and your prob should be fixed