Ri5e

Yes, I did a search and have found similar posts but they resolved it through replacing the IACV, which I did too.

The car is a 2002 Honda Accord EX V6 Automatic with 82K miles. The car was running fine last week. I had it sit for a week and then yesterday the idle surge started. When the car is first started, it idles at like 2,200 RPM and then after 35 seconds, it bounces up and down from 1,500 RPM to 2,200 RPM. It does this in both park and idle. When I put it into gear (Drive or Reverse), the Idle sits at 1,200 RPM and it feels like someone is pushing on the gas as I hold down on the brake pedal.

There is no CEL.

I removed the IACV and cleaned it to ensure the flapper moves freely and pops back down. I put it back in and it threw a TCS code and CEL (P505). So I purchased a new IACV and put it in and it still does the same thing, except no CEL / TCS code.

I noticed it is pulling in tremendous amount of air before the throttle body plate, where the IACV allows air in. So when I put my finger over the hole, the idle is back down and smooth, no surge.

I pulled the MAP harness, car almost stalls out and CEL comes on.
I pulled the TPS harness, same bouncy idle and CEL comes on.
I pulled the IACV harness, car hovers / surges between 1,500 RPM and 1,550 RPM and CEL comes on.
I pulled the coolant temperature sensor and idle still surges and CEL comes on. I replaced this, same thing.

I checked the PCV (Pinched the hose that connects to it) and idle still surges.

Lots of air is still going in through that IACV hole, so it's acting like a huge vacuum leak.

Could it be a bad ECU? Not sure what else could be the issue. Any help is appreciated. Thanks!

holmesnmanny

Sounds simply enough like the iacv is bad and letting too much air through.

Ri5e

I replaced the IACV with a brand new one.

Ri5e

Alright, fixed the issue! I bought another IACV and tried it and it worked! The one that was sold to me by the Advanced Auto Parts, the valve was stuck and halfway open. Can't believe they sold a defective part. So be sure to check the valve and that it is closed fully and when pushed open with a small flat head screwdriver, it should pop back down.

holmesnmanny

It's not often even an aftermarket iacv is bad. Never had one bad out of the box. I suppose it does happen.