B18b idle fluctuations in eg hatch
 

1994 civic hatchback with a B18b swap. The idle is fine when its cold and it drives fine. When it warms up, it will idle ok for a few seconds and then the rpms drop and come back up. It idles fine again for a few more seconds and repeats.

I have already tried a good known working iacv and ecu. It’s running on a p75 ecu obd1, no check engine lights. New cap and rotor. New timing belt and timing is correct. Coolant has been bled.
I will attach a video I uploaded on YouTube for you to watch. There’s some long pauses between idle drops because it doesn’t do it all the time. Ive got a couple guesses but I’m open to suggestions on the cause. I did the swap in October 18’ but the car has been in storage since November so I haven’t really messed with it since then. The vibrations are from my exhaust needing adjusted.

Re: B18b idle fluctuations in eg hatch
 

IACV on back of intake manifold....

Re: B18b idle fluctuations in eg hatch
 

Re: B18b idle fluctuations in eg hatch
 

Re: B18b idle fluctuations in eg hatch
 

Re: B18b idle fluctuations in eg hatch
 

Finally had a chance to get to the garage and adjust idle. Made very fine adjustments and still having same symptoms.

Tried another throttle body with different tps and map sensor. Still has same symptoms.

Im open to any other suggestions. I’ve had a lot of Honda’s and never had this happen before.

Re: B18b idle fluctuations in eg hatch
 

Try your ecu in another B18B1 swap or Integra and determine is same issue is present.

Verify fuel pressure at idle and when it dies over. Try another working FPR, replace fuel filter while you are at it, then send your injectors off for flow test/cleaning or replace injectors with known working stock 240cc.

Pressurize the coolant system to check for leaks there as well.