Did you adjust the throttle plate stop screw? This should never be adjusted. You adjust the idle air bypass screw in the throttle body entrance TDC.

Lateral throttle cable slack is adjusted to 10-12mm (3/8-1/2 inch).

good luck

 

I adjusted the screw that is recessed into the throttle body right above the plate. I'm guessing that's the wrong one? Either way, it's back where it was now. Where is the idle air bypass screw?

Lateral as in total up and down slack when the throttle is pushed to the stop? Sorry, I'm just trying to make sure I do this right.

 

Not clear what you adjusted. If you adjusted the bleed screw Top Dead Center of throttle body entrance, that is correct screw to adjust idle. Idle is adjusted w/ the Evap purge valve disconnected. IACV remains connected. No load speed is 700+/- 50 rpm and loaded (AC on, blower fan max) to 770 +/- 50 rpm.

Yes, lateral is any direction perpendicular to cable direction.

You really need a shop manual. See automanualsource.com for a cheap download manual, $22.

good luck

 

That is the manual I'm using. I downloaded it for about that much from, I believe, that site nearly a year ago.

Okay, so my throttle cable must be too loose, as there is at least a couple of inches of lateral movement up and down with the lever moved to the stop. I did disconnect the EVAP purge valve before I started.

The screw I adjusted is the large slotted one just to the left of TDC. I see a hole in the body at TDC, but can't see down into it. Is that the one I should be working with?

 

Look in your manual (page 11-110) at Idle Adjustment under Fuel and Emissions chapter. It shows the position of the idle air bypass screw on the throttle body.

good luck

 

Okay, so I snugged up the cable and now the throttle is a little more responsive. However, the idle remains the same. Also, when I give it more gas when accelerating, say uphill, it seems more sluggish and doesn't have the "umpfh" it had before, and as a result it kicks down easier than it did before. The screw shown in the manual is the exact one I adjusted, but it's as tight as it will go.

 

Air in the cooling system can cause strange idle problems on hondas. When you filled the coolant, did you purge the air from the system? Search youtube for an ericthecarguy video on how to do this.

If the cooling system is good, then I would start searching for a vacuum leak. I think propane is the safer method compared to spraying carb cleaner.

If you have a scan tool, you may want to look at the long and short term fuel trim.

 

There are no vacuum leaks anywhere. I've looked high and low and found none. The air has been (at least mostly) burped from the cooling system.

 

Alrighty, so the check engine light stayed off for a few days and everything was fine except for the slightly high idle. Then, out of nowhere, the light came on again and the engine started to surge, though not as severely as before. I removed the valve again and found it was still a little sticky. I filled the cavity with brake cleaner and let it sit for about 10-15 minutes, then I sprayed it out really good and ensured that it was free to operate. Put it back on, and while there's no surging, the idle is still a bit off and it keeps throwing the P0505 code. I'm pretty convinced that the valve is done for, but I discovered something else. When I disconnected the third vacuum line from the valve wit the engine running, there was no vacuum present whether at idle or open throttle. I'm confused. Any thoughts?

 

Check your manual for code P0505. You may have a defective IACV.

No idea what "third vacuum line from valve" means.

good luck