I have a 5th generation H22a4 and I have this weird idle drop. When the car is at normal operating temperature, the idle is fine at 720 RPM, which is normal RPM for a manual transmission. But when I'm in neutral and rev up or I'm parallel parking, and I let go of the accelerator, the idle drops to the point that the RPM needle is almost hitting to 0 RPM, the car shakes and It feels like It's about to turn off, then it goes back up to its normal 720 RPM. What could cause this idle drop?!!


Modified by LudeNEzz at 4:42 PM 7/4/2007

 

dude, mine does that **** all the time. i don't think theres anything wrong with it

basically i think the shake is kinda like killing the car by taking your foot off the clutch in first gear. kinda the same feel when the car jumps because of a hydraulic clutch. and as for the needle hitting zero, it probably isnt. its probably just bouncing

idk. no one responded but just wanted to let you know theres probably NOTHING wrong lol

 

https://honda-tech.com/zerothread/2032337

 

My 4th Gen. does the same.
I have all ready cleaned and fixed my IACV.
Sometimes it does it, and sometimes it doesn't

When it does do it, it will fluctuate a tiny bit for a short amount of time before settling at a RPM.

Before I ever messed with my IACV, my idle used to go up and down a lot, and the car was barely drivable. I found out that the valve inside the IAC was completely loose and not even screwed in. So that was causing a vacuum leak for me. But now that portion is fixed and my idle still drops sometimes. I wonder if its something else. It's hell of a lot better than what it was before so I really haven't bothered to look more into it.

 

Well you should also open of the FITV and screw the round plastic piece back in if it's undone, it's another source of a vacuum leak that you should check. There are plenty of write ups on trouble shooting idle issues. The main things seem to be clean out IACV, open up and inspect the FITV, clean the throttle body, and check for other obvious vacuum leaks.