Hi everybody, today I got in my car and realized something is wired and all the sudden it started acting crazy. When the car is on park, the RPM goes to 2k and then it comes back to 1k, it does this every second. It is like somebody pushing on the gas pedal and then releasing. I waited for a while may be wondering that it would go away, and then the check engine light came on. I drove to advanced auto and checked with their diagnostic tool and it gave an error on idle air control system. I am not sure if that could cause the problem or if it is something else? And other question is where it is located. The car is 98 Accord V6. I know it should be somewhere on throttle body but there seems like there are 3 different sensor on there. If you think the idle sensor is the problem what would be the least expensive way to fix it? Thanks a lot.

 

try cleaning your IACV [idle air control valve] before you replace it ... it'll run you about 100 bucks ...

here's a link to repair guide:

http://www.autozone.com/shoppi...3a1d9

 

I am not sure where it is located ? and how do you clean it ? thanks

 

The Idle Air Control system controls the idle. Of course it would cause the problem. It controls the idle by passing or restricting air flow into the throttle body. The IACV (idle air control valve) is cylindrically shaped and lays in a horizontal direction to the throttle body. If you search you'll find write-ups on how to clean/check the IACV. There is also a fast idle valve (FIV) that can cause similar symptoms, but I would check the IACV first.

 

im not sure where on the throttle body its located on a v6 ... ill see if i can find out where exactly ... you can clean it with carb cleaner or brake cleaner

 

Thanks, please let me know if you find out where it is, because there are 3 sensors on throttle one at the bottom one on the side and one on very top.

 

i think its on the front side of the throttle body ... it looks like this

 

I also found this https://honda-tech.com/zerothread?id=2392140

Which says it is the one at the bottom but do you think shall I take verything apart or just the IACV ? thanks for all your help

 

good find i did a search but found nothing ... well its really up to you ... but all you really need to do is clean the iacv

 

Thanks a lot for all you help, I will let you know if it is fixed. Thanks again

 

High Idle speed and Fluctuation troubleshooting

Leaking EACV- Disconnect EACV connector. Idle speed should decrease. With the connector disconnected block the hole in the intake port or pinch the hose from the air cleaner to the EACV. If the idle speed decreases the valve is leaking. This condition will not set a code. The ECM can only detect an open or short circuit. It also may clog it’s screen if it has one.

Leaking IAC- (Idle air control valve) Disconnect IAC connector. Idle speed should decrease. With the connector disconnected, block the hole or pinch the hose to the IAC valve. If the idle speed decreases the valve is leaking. May not set a code and may not be a codeable circuit on all models.

TW or ECT sensor- (engine coolant temperature sensor) voltage should be about 3.0 volts @ 60 deg F and between .55 & .7 volts @ normal operating temp. If the voltage is above .8 volts at normal operating temp, will cause rich mixture and high idle speed. May not set a code because it is not far enough out of its operating parameters. **Also this sensor will not read temperature correctly if coolant is low. (beware)

Vacuum leaks- a loose vacuum hose or leaking intake manifold gasket can cause high idle speed and/or fluctuation. Also check for bad PCV valve.

Fast Idle Valve- (if equipped) a fast idle valve that is sticking can cause high idle speed and fluctuation. Check it by removing the steel cap on the top and putting your finger over the hole in the middle of the seat under the cap or block the port just inside of the throttle body opening, when the Idle is fluctuating or staying high. When the engine is warm this valve should be closed. You can tighten the seat but it will also change the idle speed warm up values (closing).

Throttle valve- throttle position sensor voltage should be .5 volts with the throttle closed. Make sure the throttle valve is fully closed and voltage is within spec.

ECU-If all else is good, if you reset the ECU and the problem goes away temporarily, the ECU may be defective.

Verify that the cooling system is full of coolant and
there is no air in it.

Remove the air boot from the throttle body and cover the
throttle body with something that will stop the airflow
(your hand, tape) with the engine running. With the
throttle body covered and no air going into the engine, the
engine should stall. If the engine does not stall, look for
a vacuum leak. With the engine running and the coolant
temperature above 90 degrees F, verify that there is no
vacuum on the lower port in the throttle body. If it does
not lose vacuum, look for a faulty fast idle valve on the
bottom of the throttle body, as long as the coolant hose is
good and hot.

Verify that the base idle screw was not turned way out on
the top of the throttle body. If it was, set the base idle
and see if the problem still occurs.

The upper port in front of the throttle plates feeds the
Idle Air Control (IAC) valve and the base idle screw. If
the IAC is unplugged and the base idle screw is turned all
the way in and there is still airflow through the upper
port, check for a stuck open IAC valve.