1999CivicSi

I have a 99 civic si b16A2. Have been having a fluctuating idle, especially after giving a little gas. It will jump idle for a min then go back to normal idle. Just took my Throttle body off to clean and it started this. Has idled rough in the past, but never like this. Tryed to reset ecu, didn't work, cleaned the iacv, didn't work. someone please help if u may know whats wrong. Need my car for work. Thanx,
1999CivicSi

ezone

Just a SWAG, let it do an idle learn.

Get it fully warmed up, turn everything electrical OFF, and let it idle for 10 minutes in neutral or park.

HTH

1999CivicSi

disconnected battery then re connected after ten seconds then started car with all electrical components off and foot of gas and brake. let idle for ten minutes. shut it off then started again. still and idle surge. thinkin its the fast idle thermo valve,if i have one on my b16a2... if not then possibly a sensor??? And when i took my tb off i disconnected the tps sensor and the map sensor..could that have caused the problem..

ezone

Oh, now it is a surge? How much of a surge? 2000 to 1200 RPM over and over? Something different from that?

I can't hear what it acts like so I'm only guessing here.

Vacuum leaks, stuck open IAC valve....something along those lines?
Wrong adjustment on the air bypass screw?
Pull the tube off the throttle body, plug off the port for the IAC with your finger and see if the surges stop. See what the idle speed is when you plug that port off.

1999CivicSi

its actually almost a fast fluctuating idle. dont have a tac..so cant tell rpm. what tube do i pull and there are two ports on the iacv...wich one to clog or whatever...

ezone

Read this thread here maybe you can pick up some clues https://www.civicforums.com/forums/1...e-problem.html
Post #6 I got a few chuckles out of.

Maybe yours ain't exactly the same, but check it out...
Ports in the throttle body, like this:



Also, this quote from that thread, since you say you don't have a tach: "..... and use a tach. Consult the Factory Manual for the proper procedure. Don't just **** around with the screw."

04 Honda Civic

iTrader: (2)

Didi you screw up the gasket on the tb?

You use a new gasket or the old one? If it ripped that could cause your problems as you have now created a vaccum leak.

I dont believe it is necessary to remove the tb to clean in. Simply remove the air filter and spray some carb cleaner in the tb and wipe as best as you can.

I could be wrong but usually acess to the tb is generally easy.

1999CivicSi

I fixed the problem!!! Did a diagnostics test threw codes P0420 catalyst system, and P0505 Idle Air Control System. So went ahead and bout an oem replacement IACV and fixed the problem.Thinkin the cat prob is the downstream O2 sensor.. by the way that IACV was not cheap like $180.00, but worth it. Thanks everyone for your help and advise!

ezone

So the IAC was stuck or something? Cool beans.

BZZZZZZZT!
Wrong answer.
Thanks for playing.

1999CivicSi

im guessing it was. had cleaned it about two months ago, and it finally decided to fully take a crap on me.