I used the search function for hours but nobody else seems to have a problem quite like this.

So I'm driving a manual 95 gsr with a 93 b18a1 engine and tanny swapped into it (other engine blew). The egr has been deleted and it has the ls ecu with the gsr wiring harness. My only mods are a 3 inch sri and headers to the gsr exhaust. My problem is that the idle surges when cold from 2k to 3k but after about 5 minutes the problem goes away and it idles at 800. So obviously at first I thought it was the FITV since it seems to be related to heat, but when I plug the bottom port of the tb the problem doesnt go away and actually all of the suction is coming from the top port which goes to the iacv. Another weird thing is that the idle problem goes away if i open tb plate at all. So I guess my only options are iacv and tps but I've never heard of either of these systems having a heat related problem like this.
I've tried blocking off the fitv, cleaning the fitv and iacv, and screwing in the fitv valve (though it wont screw in until tight so it could be stripped). I've bled the coolant too and replaced the pcv. There are no CEL codes

 

Can you not just transfer over the known working parts from your original engine that blew?

 

No I don't have that motor anymore unfortunately. I'm really trying to nail down the exact cause rather than throw parts at it

 

What intake manifold is on there? Take a pic and upload.

 

The 93 Integra pgm-fi. I'll get a pic when I can.

 

And what specific yr/model ecu you're using?

 

Another thing, There was discussion back in the day on TI that the IACV is different, so if you have a 94-95 ls ecu than you'll need an 94-95 iacv. Its been a while since I've messed with a b-series.

You can also try to replace the iacv gasket, reset the ecu and do the re-learn idle process.

If you rev it and its not backfiring than your tps is probably good, make sure your gaskets, all involved with the intake manifold and throttlebody, are good and not leaking.

 

The one from the 93 ls.

 

Ecu is a p75-A51

 

Here's the im

 

See if you can borrow a 94-95 iacv, I think thats an automatic ecu but not sure if it will have issues, also check all of your blockup connections to make sure they are air tight.

 

OK, so on my 92, there is the IACV (idle air control valve) located under the throttle body. It has a small coolant hose running to it. The valve can be serviced by removing it, and taking off the 2 Phillips head screws. Then you can screw the valve back in if it has rotated out of place. Also there is an EIC. (Electric idle control) located on the back of the intake. I had an issue where it wouldn't hold idle until it was warmed up. Replaced the EIC with a used one off another intake I had. Ran fine after that.

 

EIC Electric Idle control. Cannot be serviced, only replaced.
IACV Idle Air Control Valve. Can be serviced / adjusted.

 

It looks like you have a fitv valve under the throttle body. Should be 2 8mm/10mm I cant remember but it’s dirty or came unscrewed. Tighten it up and it should be good to go.

 

That's my car, not the person posting. It's the idle air control valve under the throttle body. In newer models it couldn't be serviced only replaced. But the electric idle control on the back of the intake manifold is the likely culprit if the next generation Integra still used them.

 

I've tried tightening the valve under the TB but it didn't work, I even blocked off the FITV but it didnt working either. I think i found the culprit though. Like some others are saying I think I have the wrong IACV for the ECU (or just a broken one). I warmed up the car until the bouncing stopped and then unplugged the iacv electrical connection. The idle dropped to a lovely 750 from 1100 and I even took it for a drive (it would buck if you let your foot off the gas in 3rd but other than that it was fine). I then adjusted the other screw to stock specs, turned it off and then turned it on again with the connection unplugged and it started as if nothing was wrong. I turned it off and re plugged in the connection but the idle started bouncing and then hovered at 1100. It definitely seems like a broken IACV so I think I'll run over to AutoZone and replace it to see what happens.

 

Well I replaced the iacv with a working used one and nothing changed, I screwed back in the FITV port and same story. I learned that my intake mani is from a 91 Integra though so that's interesting. It's very possible that this is an ECU issue since it's a p75 working with 91 and 93 parts. One weird thing is that the FITV port in the throttle body doesn't suck in air ever, even when cold. I'm just confused at this point but don't want to visit a mechanic since they'll just tell me its the iacv.