96 DX

I recently replaced the head gasket and refreshed the head on my D16y7, ever since then I've been having a surging issue. I've changed the iacv, the entire manifold, reset the ecu, covered the iacv hole in the tb, checked for vacuum leaks but none of my attempts have proven successful. I, however, hear a vacuum leak (if that makes sense to you) but it's coming from inside the tb/manifold so I'm unsure of what to do at this point

 

Have you replaced the TB and IM gaskets, and torqued the nuts/bolts to spec?

 

Yes I have, as stated I even went the route of swapping a complete y8 manifold (minus injectors) onto the car but that effort proved futile as well

 

Not stated.

 

That was supposed to be: yes I have torqued the nuts and bolts to spec. Then: as stated I even went ahead and changed the manifold.
But anyhow, I torqued every nut and bolt to spec, changed every gasket, cleaned the iacv out, put a new one in but still no positive results

 

I have yet to know any mind readers in this forum.

Stock D16Y7 IM and TB?

What happened when you covered the IACV hole in the TB?

 

Yes, I had the stock d16y7 im and tb on when the problem first started. Then I changed to a different y7 im and tb with no luck. And just yesterday I changed to a y8 im with the y7 tb. When I covered the iacv hole in the tb there was no difference in the idle

 

Based on the information you provided, there's either an intake air (TB/IM) or vacuum leak.

How high is the idle speed and what's the rpm range of the surging?

 

On a cold start the rpm goes all the way up to 4000 rpms and when it comes down it surges from 1200 rpms to 2000 rpms

 

Are you unable to kill the idling engine by covering the top of the TB with the palm of your hand?

 

Yes sir, that is correct. I am unable to kill it. It lowers the rpms barely but the surging continues

 

UPDATE:
I just went to start the car and the surging is now from 1400 rpms to 2900 rpms and with the AC on 1600-2400

 

There's a massive intake air or vacuum leak that you've missed.

 

I'll double check it but I don't see where it could be coming from that I've missed

 

The unambiguous diagnosis of a massive intake air/vacuum leak is based completely on information you have provided.

 

I know. I appreciate the help. Thank you for the insight sir

 

Alright, so after doing some extensive research I figured out that my vacuum leak (originally diagnosed by RonJ) was coming from the cold start assist system in my IM as it is from a 99-00 model. So to do a quick fix so I could go to work I sealed the holes with Hondabond and lo and behold my vacuum leak was gone. So I'm still trying to figure out a permanent fix. Any suggestions?

 

Why not reinstall the Y7 IM and TB?

 

The IACV from the Y7 was actually bad. Tried it on another car. Also I figured I'd just stay with the Y8 manifold (mostly because I prefer a horizontally mounted TB) since it would be easier to mount a strut brace with that manifold on

 

Is the Y8 IACV mounted on the TB and does it have a 3-wire connector like the Y7 IACV?

 

jb weld/sand smooth the cold start assist holes. hondabond will probably get sucked into it.

 

The Y8 IM I have is an automatic one and I used a Y7 TB on it so there's no IACV mounted on the back of it. Everything is on the TB

 

Thanks for the suggestion. My problem though is that I tried to remove the gasket from the IM but it's stuck on it and I really don't want to damage it only to end up with the same problem I've just resolved. But is it absolutely necessary to sand the jb weld? Because it doesn't even make contact with the head (does it?)

 

I think the 3-wire IACV on the Y8 TB would work with the Y7 IM/TB. That would be the easiest fix, though apparently not the route you wish to take.

 

The IACV I have now actually works. Which is the new one I bought. My vacuum leak is coming from the cold start assist holes in the IM