2012 Civic, 185k miles.

Last week I removed my throttle body and gave it a good cleaning. The only symptoms I had prior to doing it were a rough / shaky idle and lots of hesitation on acceleration.

Now the rough/shaky idle and hesitation are 100% gone (runs and accelerates like a beast), however I now have two new things going on.

*Only on cold starts* I noticed my car takes a couple seconds longer to crank.. sounds like a weak battery but I tested the battery/alternator, both are good. Also for the first 5-6 minutes after a cold start, my car pulses significantly like it's choking/struggling to breathe and my idle RPM jumps from 1,500 - 1,700 until it slowly stabilizes around 800-900. Once warm, my car will shut off/crank completely normally and I don't have any pulsing/choking whatsoever.

The other issue is when I give the gas pedal a quick hard press, the RPMs will go up as expected.. all normal there. But after I quickly take my foot off the gas the RPMs will come down to 1,000 then spike up to 1,200, then down again to a normal idle level. Hopefully that makes sense.

Maybe a bad TB gasket?

 

Clean IACV and adjust.

You can check for vac leaks with a BIC lighter flick lighter and hold it on with out lighting it, pass lighter over suspected leak area, if RPMs increase you have a leak. 94

 

yup, IACV causes surges like no other.....

 

Thanks, pretty sure it's my IAC causing some annoying issues.

Could the IAC kick in after I remove my foot from the gas pedal but while I'm still cruising? I'm curious if my clogged IAC is the reason my RPMs spike a little after I take my foot off the gas.

My theory is that as I remove my foot from the gas, the throttle plate 'closes' and the IAC essentially kicks in for air. But since it's clogged, the throttle plate is being opened back up causing an RPM spike.

No clue if that's possible or if the IAC would kick in after taking my foot off the pedal (since I'm not technically "at idle").

Still learning but trying to understand and do as much of my own stuff as I can.

Thanks

 

the iacv is set up so it sucks in air and flows liquid through it when u step on the gas so if there is a vaccuum leak or air in the line it will bog....make sure to check for an cracks in the hoses.....

 

Thanks I'll take a look tomorrow to see if I can see any cracks.

As for the IACV, I was under the impression that it was on the top of my throttle body while the FITV was below. But taking a look at these diagrams from Honda it looks like the MAP sensor is above the throttle body.

Do you know which (if any) of these is my IACV? Haven't been able to find many details on any diagrams.