My idle has never been steady on my B16A3 del sol, so yesterday I got some unexpected free time and decided to pop the hood. Went to adjust the idle to see if that would help the surging, however, after fully removing the screw the idle did nothing. Still idles around 850-900 and still does the famous idle surge but now another piece to my puzzle has been added. Why would it idle with the screw fully removed? Should that not make it idle extremely high? Any logic would be appreciated.

 

So it looks like I have some people on H-T stumped, or just not willing to put any input on the situation. Guess I'll just have to ask which wheels to put on my car or something like that....Come on guys I know there are some decent techs on this site with valuable info to share, help a guy out.

 

I had this problem with my 97 teg with a B18B1, and then again with my 94 civic with a D15B7. Both were caused by a gasket. The intake manifold gasket on the teg and the throttle body gasket on the civic. And yes I tried your solution of messing with the idle screw. That won't help since this is a vacuum-related issue. So from my experience I would check the gaskets. Also, the IACV, FITV, and ECU to name a few. Good luck.

 

I got your fix.

Just under the throttle body you should have a FITV or something. It will have a cap on the end by the firewall most likely.
That cap will have either 1) 2 8 mm bolt heads with a phillips slot in it or 2) 2 phillips head screws

Remove both of those and the cap. Don't loose them they will fall and are hard to find haha I know.

There will be a white circle with a hole in the middle and 2 slots on either side. Take a flat tip screwdriver (wide tip) and screw that in like a bolt or something (righty tighty)
It should snug up, but don't force it.

Re-install cap and screws/bolts and start car up. No more surging.

I have done this to about 8 hondas locally and everyone is amazed because they wasted hours and lots of money trying to throw parts at it.

What is causing this is that thing backed off letting too much air through the TB and the ecu sees the air via map (vacuum) and adds fuel. It keeps getting confused and keeps trying to play cat and mouse to solve itself.

But since its a mechanical issue it will never go away until resolved.

The reason it doesn't do it right away on start up is because the IACV is letting air in to idle faster to warm up the motor. When that closes you have idle surging via the FITV.

Let me know how this works for you.

 

Have done that, and right now the FITV is no longer there. Ebay had a CNC machined plate that eliminates the FITV, works well and cleans up under the TB. As far as the idle hunt it doesn't do that all the time, if for instance, i'm at a stop light and it starts surging I can put a slight load on it for a few seconds let it find idle and the resume neutral and it is gone.

 

Sounds like a fun one to trouble shoot. Wish I was closer to help but without seeing it that will be hard to e-diagnose.

 

ya i have done that to a bunch of Hondas too... im not sure why that plastic piece backs out

 

vibration most likely. frequency vibration??

 

LOL 'fun one' yeah it's been a PITA ever since I owned the car. Almost to the point where I'm gonna buy a chipped p28 to rule out this ECU.

 

Faulty IACV or circuit?

Air trapped in the cooling system?

Intake air/vacuum leak?

CEL?

Can you kill the engine by choking the throttle body with your hand?

 

Yes I can kill the engine with my hand, and bled the cooling system. Faulty circuits could be a the case, how would one go about checking that?