98 Accord IAC question

[JeffKeryk]

1998 Accord LX 2.3 4 banger, 185K. Lean idle surge between 900 and 1800 RPM once it warms. Threw a P0505 trouble code.

Cleaned throttle body butterfly area and tapped on IAC with small ball peen; helped but surge came back.
Ordered IAC from Autozone due to 20% off coupon. Part arrived with cellophane tape on box. IAC had been installed previously; it had a little grease and marks for the bolts. I think I paid about $170 with discount. Otherwise appears new.

Would you chance installing this part or return for another? Also, the Denso OE part is probably pretty expensive. Any guidance or tips is appreciated.

Is there a test for the IAC with it off the car? I can clean it....

I am fixing this Accord up for a needy person. Needs tires and alignment next but wanna sort this first.

 

[dogememe]

Exchange it for sure. Do you have time to get one at a junkyard?

 

[Astro14]

Personally, I would return it.

I am a fan of OEM parts to begin with, particularly when it comes to sensors and actuators, so this part already had one strike against it.

The fact that it was installed means that somebody could’ve buggered it up, cracked it, or exposed it to an electrical spike that renders it inoperable.

Generally, there is no return on electrical parts like this, so I’m surprised that the store took it back.

 

[Brian123]

1998 Accord LX 2.3 4 banger, 185K. Lean idle surge between 900 and 1800 RPM once it warms. Threw a P0505 trouble code.

Cleaned throttle body butterfly area and tapped on IAC with small ball peen; helped but surge came back.
Ordered IAC from Autozone due to 20% off coupon. Part arrived with cellophane tape on box. IAC had been installed previously; it had a little grease and marks for the bolts. I think I paid about $170 with discount. Otherwise appears new.

Would you chance installing this part or return for another? Also, the Denso OE part is probably pretty expensive. Any guidance or tips is appreciated.

Is there a test for the IAC with it off the car? I can clean it....

I am fixing this Accord up for a needy person. Needs tires and alignment next but wanna sort this first.

The P0505 code indicates an Idle Control System Malfunction in your vehicle. This code is triggered when the Engine Control Module (ECM) detects that the idle speed control system is not functioning properly, meaning the engine idle is either too high or too low. The issue may be related to the Idle Air Control (IAC) valve or its components. To diagnose and fix this code, you may need to inspect the IAC valve, check for vacuum leaks, or examine the wiring and connectors associated with the idle control system.

You might want to look at other things besides the IAC Valve.

 

[mk378]

These engines will idle surge if the coolant level is low.

Tests of the valve off the car would be to confirm closed with no power applied, and test the resistance of the solenoid.

On the car, pull the connector off and the engine should idle very low (or possibly stall) but steady. This will throw the IAC Circuit code. Adjust the idle air bleed valve screw on the throttle body for a lower than normal (450 rpm) idle but not stalling with the connector disconnected.

It being MAP controlled, air leaks anywhere will cause a high idle.

 

[FZ1]

1998 Accord LX 2.3 4 banger, 185K. Lean idle surge between 900 and 1800 RPM once it warms. Threw a P0505 trouble code.

Cleaned throttle body butterfly area and tapped on IAC with small ball peen; helped but surge came back.
Ordered IAC from Autozone due to 20% off coupon. Part arrived with cellophane tape on box. IAC had been installed previously; it had a little grease and marks for the bolts. I think I paid about $170 with discount. Otherwise appears new.

Would you chance installing this part or return for another? Also, the Denso OE part is probably pretty expensive. Any guidance or tips is appreciated.

Is there a test for the IAC with it off the car? I can clean it....

I am fixing this Accord up for a needy person. Needs tires and alignment next but wanna sort this first.

Return.

 

[GMBoy]

Personally, I would return it.

I am a fan of OEM parts to begin with, particularly when it comes to sensors and actuators, so this part already had one strike against it.

The fact that it was installed means that somebody could’ve buggered it up, cracked it, or exposed it to an electrical spike that renders it inoperable.

Generally, there is no return on electrical parts like this, so I’m surprised that the store took it back.

With that being a Rock auto part one of 2 scenarios happened that allowed him to get an opened/used part that the box was taped up:

1. Rockauto buys up inventory all over the world from closing parts stores, over stocks and all that so the part may have been purchased like that by RA and they just passed it on

2. When returning anything from RA it is all up to how you answer the online questions if they will accept the part. If you answer in a way that it seems their catalog was wrong or wrong part in box they will take it back.....examine and usually back on the shelf it goes unfortunately,

 

[JeffKeryk]

Pics of OE IAC before cleaning:

AutoZone IAC with previous install witness marks. There are more and grease smudges.

 

[JeffKeryk]

These engines will idle surge if the coolant level is low.

Tests of the valve off the car would be to confirm closed with no power applied, and test the resistance of the solenoid.

On the car, pull the connector off and the engine should idle very low (or possibly stall) but steady. This will throw the IAC Circuit code. Adjust the idle air bleed valve screw on the throttle body for a lower than normal (450 rpm) idle but not stalling with the connector disconnected.

It being MAP controlled, air leaks anywhere will cause a high idle.

Wish I would have posted this before disassembly... Sheesh.
The engine idles beautifully upon startup but surges once coolant flows. Engine drives perfectly.
I figured it was the IAC because of this and when I lightly tapped on it 30 times the idle smoothed out. It was a little high, 1,000 RPM but steady.

Now that I have cleaned it, I am tempted to reinstall... Your thoughts?

 

[iCurious]

If there is no vacuum leaks then it's most likely the IACV. And cleaning it does not always solve the problem.

Buying IACV from parts store is definitely a hit and miss.

 

[Nukeman7]

Your surging/pulsing idle speed symptoms sound exactly like the issues that I recently resolved on a Honda K24 engine. That IACV appears to be identical to the one on your 1998 Accord and you will need to thoroughly clean it out with carb cleaner, a toothbrush and a pick tool. Once it spins freely, oil both ends of the shaft with a drop of light oil (e.g., Kroil, 3-in-One, etc.). Reinstall it with a new gasket...the Mahle at AutoZone fits perfect. I tried two aftermarket IACVs and neither one worked correctly with the PCM.

 

[researcher]

1998 Accord LX 2.3 4 banger, 185K. Lean idle surge between 900 and 1800 RPM once it warms. Threw a P0505 trouble code.

Cleaned throttle body butterfly area and tapped on IAC with small ball peen; helped but surge came back.
Ordered IAC from Autozone due to 20% off coupon. Part arrived with cellophane tape on box. IAC had been installed previously; it had a little grease and marks for the bolts. I think I paid about $170 with discount. Otherwise appears new.

Would you chance installing this part or return for another? Also, the Denso OE part is probably pretty expensive. Any guidance or tips is appreciated.

Is there a test for the IAC with it off the car? I can clean it....

I am fixing this Accord up for a needy person. Needs tires and alignment next but wanna sort this first.

Jeff- let me tell you I had exactly the same issue on my 96 Civic that you're having now with your Accord. It did NOT matter how much I cleaned the IACV it would not correct the issue.

I went through the aftermarket JUNK and if the one you have has Denso's name on it, they are the rejects from the production line Honda uses. Honda gets the good ones, the aftermarket gets the rejects.

No matter what I did the aftermarket would not correct the problem continued the up/down rpm surge and yes same CEL number. I had to spend the $$ for Honda's part, then bam! No more issues. Hope that helps you.