Up & Down idle issue and check engine engine light!
 

From having weak idle on my 97 DX D16y7, I cleaned IACV and throttle body. After put them back on, idle started up and down with certain rhythm. Also there is check engine light came on.
I haven’t bleed air out of coolant yet.

Should I start with bleeding air out of coolant or diagnose check engine light first?

Re: Up & Down idle issue and check engine engine light!
 

May sound dumb, but double check that everything is plugged in properly?

Re: Up & Down idle issue and check engine engine light!
 

Coolant bleed:
Raise front of car as high as possible on jackstands
Turn climate control on max heat, recirculate mode, and fan off
Run engine (rad cap off) until radaitor fans turns on twice..add coolant mix as needed to radioator and reservoir.

After bleeding the coolant do an ECU reset (idle learn) at operating temp.

Re: Up & Down idle issue and check engine engine light!
 

not sure if you got this problem resolved yet or if you're even coming back to this forum...as megalodong said with the coolant bleed procedure and ecu reset...do those...the cel will go away when the battery is disconnected...if it comes back and it's still saying iacv then replace it...or better yet...check the wiring for it...clean the connection point...hell...look at your fuses...if all good then replace it......you'll be opening up the coolant system again by doing so, so bleeding again will be necessary...even a little air can cause a headache...and it doesn't take long anyways so why risk it...

a cleaner method for the bleed is get a "spill proof" funnel...works wonders

and riceboy is 100% correct..."Is it plugged in?" should be number one question when dealing with honda electrical systems...IACV valves rarely....yes i said rarely...not never....go bad...more times than not a rough idle is air in the coolant system