Dear Experts,

I have a:
1996 Honda Accord EX
~ 279K miles
2.2 VTEC engine
5 speed manual transmission


In earlier years, when stopped, the idle would be about 700 RPM

But the past year or two, when stopped, the RPM of engine races.
From what I remember, the RPM bounced between 1000 and about 1750 RPM.

It was much worse in the winter. Always high.
This summer, it was calmer. But rarely went below 1000 RPM.



...

After a lot of research, recently I changed the:


Honda 16500-P0A-A01
Valve Assembly, Fast Idle (Af41D)
1994-2001 Honda
16500P0AA01
https://www.hondapartsnow.com/genuin...0-p0a-a01.html

(OEM part)

...

Idle Air Control Valve (slow)

Honda 36450-P0A-A01
Valve Assembly, Electronic Air Control
1994-1997 Honda Accord
36450P0AA01
https://www.hondapartsnow.com/genuin...0-p0a-a01.html

This is now discontinued, so I bought an aftermarket part on Ebay.

....

Yes, I bled the cooling system of air bubbles.


And, an aftermarket PCV valve from Autozone.
https://www.autozone.com/emission-co...3dl/918540_0_0


....


But the idle is still races high.
Yesterday, the idle fluctuated between 1000 and 1750 RPM
I've seen it bounce up to 2000 RPM.

...

Additional info:

Previous years, there was the check engine light code:
P0401
Exhaust Gas Recirculation Insufficient Flow

The past two years, in the winter especially, I keep getting the check engine light code,
P1491
EGR valve lift insufficient detected

Sometimes, only a few dozen miles pass, before it presents itself again.



...


q1:
Has anyone had any experience fixing a fast idle?
If so, what were the solutions?


....

Now I'm thinking that there might be a vacuum leak.
I took a look, and did not see anything obvious, like
disconnected, or cracked hoses.

And, started looking at vacuum and emissions diagrams, schematics.
Complex.


q2:
Has anyone had any experience fixing vacuum leaks?
If so, what was the solution and/or
hose (or gasket, etc) that had failed?


Thanks a lot!

 

Here is an update.

As I mentioned, the Idle Air Control Valve (slow), 36450-P0A-A01
was an aftermarket part on Ebay.

Pics here:


Aftermarket 36450-P0A-A01 from Ebay 1

---


Aftermarket 36450-P0A-A01 from Ebay 2

There was no logo on this part.

 

However, after a lot of searching, I got to RockAuto.
And found some parts there:

https://www.rockauto.com/?carcode=1167410&parttype=6072

For the EX model, there was one part from Standard Motor Products, $221.
And another from WVE, Wells Vehicle Electronics, $145.
https://www.rockauto.com/en/moreinfo...167410&pt=6072

I ordered the Wells product.

Turned out that it actually has the OEM logo (Denso) on the part
Nice!

See the images.


Wells Vehicle Products, Denso, 36450-P0A-A01

---

The part number at WVE is: 2H1125


Wells Vehicle Electronics, 2H1125, Box

---

 

Forgot to mention, before ordering the second part, I
took the car to a shop, to get checked for vacuum leaks.

They found none, but isolated the problem to the
Slow Idle Air Control Valve

Thus, my searching for another part.

After I installed this OEM part, the engine calmed down completely.
Between 730 and 875 RPM,

Yeah!


Lessons:
Always go OEM parts, when you can

Wells Vehicle Electronics makes/sells at least one great part!

So, before anyone asks, why didn't I just clean the valve; the car is 27 years old.
New parts please.

 

Many thanks to each and every one of you,
for all your helpful responses

(yes, sarcasm)