B16Power

I may be needing a new IAC and am wondering if this would be one of those parts that you want to go OEM on. The AdvanceAuto one is $175 and the Honda $295. Also was wondering if I should clean the Idle Adjustment Screw before I attempt to determine it's the IAC. Also I know inshould check for vac leaks, is carb cleaner the best option for this? Last but not least I know I may need to check the ECT if anyone could provide me with a link I'll be golden. The vehicle is a 2000 Honda Civic Si B16A2 with a CAI. Thanks in advance!

Turpid Porpoise

What makes you think its the IACV?

Yes you should clean it before you buy a new one.

Carb cleaner is great for finding vac leaks.

Former User

Any CEL codes?

Are you having any idle problems?

B16Power

Yes and Yes! Code is P0505. Secondly if the car is cold it idles and drives fine if I continue to drive it without really stopping it's fine but if I stop chances are it will start acting up. By acting up I mean the idle immediately jumps to 1500 and under any type of throttle it is very jerky and rough. Once above a certain RPM it acts better but falls very hard once releasing the gas. If I turn the car off for 5-10 minutes or so and restart it then it's fine but is possible to act up once again if I stay stationary to long.

B16Power

[QUOTE=Turpid Porpoise;46272336]What makes you think its the IACV?

Yes you should clean it before you buy a new one.

Carb cleaner is great for finding vac after the cleaning should the idle be adjusted to 700RPM while the car is acting up or acting normal, I'm thinking normal right?

Former User

A bad IACV is only one cause for P0505. What happens to the idle speed if you unplug the IACV?

Also do this:
Turn the engine off when it is hot, unplug the 2-wire ECT sensor under the distributor, and measure the resistance across the two terminals of the sensor. It should read 200-400 Ohms.

B16Power

I have not attempted to unplug it yet. Should I test it this way and not by removing the CAI and plugging the port inside the TB. I will also check the ECT and if it reads abnormal is it safe to say it's that or could a bad IAC cause that to be abnormal. If it is truly an IAC is it better to go $120 more for the Honda one vs. OE?

Former User

Just unplug the IACV.

If the Ohm reading is out of spec, then the ECT sensor is bad. This, however, does not rule the possibility of more than one problem causing P0505.

B16Power

So to test these does the car need to be acting up or no because if I leave the car off for a while upon restate it acts normal. So will the IAC still test bad, probably not right?

Former User

Try both ways

B16Power

Will do, thanks Ron!

B16Power

Hey Ron if I put the multimeter on the 2K setting I get a constant reading of .333-.336 does this sound right or do I need to be on different setting. It seems if I'm on a different setting it's hard to get a good reading n

Former User

Do you have a 200 Ohm scale?

B16Power

Yeh I tried that and it flashes high 100's at times like 186 but goes back to 1 quickly after. Is it the plug right below the Vtec solenoid or is it the green plug that goes into the solenoid. It the one under correct because it is mated with the engine head.

B16Power

Just unplugged the IAC while it was running normal it bogged down and then when I plug it back in it idles a little higher.

Former User

Your reading may be 333-336 Ohms, which would be in spec, though you may want to check the manual for your multimeter to verify.

B16Power

Ok forget my last post co poetry unplugged the wrong thing I didn't unplug the connector under the IAC I unplugged the connector to the left going into the throttle body.

B16Power

Yeh I unplugged the right connector the car almost died so it's the IAC right?

B16Power

When left unplugged the car did die.

Former User

The IACV and ECT sensor seem fine. When the idle is acting up (high or fluctuating idle), remove the air intake system and then cover the hole inside the throttle body leading to the IACV. Does the idle speed drop and steady?

B16Power

I will have to wait to get it to act up I am about to go out for a drive to see if I can because I couldn't get it to while idling in my garage I will update soon. Thanks Ron!