lsjon

So no one in prelude section could help so i figured id give it a try here. Car is a 93 si prelude. The previous owner did a blue top f20b dohc swap. Im under the impression this motor was only available in obd2. The car and engine harness is still obd1. Ive been having issues with engine surging. Typically this relates to iacv from previous experiences ive had. I checked the valve and i notice the valve has 3 prongs, and the harness plug has only 2. So i thought maybe their was a obd2-obd1 confliction. But after checking the catalog at work, the 93-01 iacv are all the same valve. So now this leads me to believe that the f20b uses a different kind of valve and possibly different manifold bolt pattern for the valve. Is this the case? and if so is their a different route i can go besides havign to swap out the manifold and valve to a usdm set up?

lsjon

ok after taking a closer look, whoever did the swap used the existing valve which came with the swap, and appears to be a obd2 accord iacv. Which has a different iacv socket end the the prelude h22 valve. So it looks like they tryed to splice a accord harness iacv socket onto the harness, but still only had 2 wires going to the socket where the valve is 3 wires. The mounting for the h22 obd1 valve i have looks to be the same as the valve thats on it. So i guess now ihave to find a prelude iacv socket to splice back into the harness, or is their a different way to just splice something to where i can keep it the way it is?

lsjon

Yay! the f20b manifold is completely different from the h22......./shoots self in nuts. So the iacv port on the manifold has 3 slots like the 99-2000 accord 4cly intake manifold and iacv, but of course 99-2000 accord usdm doesnt have butterflies. ::sigh:: so gonna get a buddies h22 manifold and use my obd1 h22 iacv and call it a day. Wish this motor was more popular for information wise ; (

lude98SH

Rosko makes an adaptor plate to run an h22 ACV on the euro R manifolds. What you could do is purchase this adaptor and an h22 IACV ( i have one for sale ) and it should plug right up. The only thing I had to do was remove the wires leading to the IACV from the wiring harness because the stock location is on the front of the manifold and on the f20b its on the rear and wouldnt reach. Also remember to run your coolant lines to it.

lsjon

iacv is on the front of my f20b manifold. And what ive been told is the euroR manifolds are different fromt he sir-t manifolds so i dont believe the adaptor plate will work.

IntegraType-R

f20b is a oustanding motor.. way better then any other accord motor
surging idle is annoying , take some chemtool b12 choke cleaner, and spray it around your TB and your manifold, if your car dies down its a gasket leak somewhere, go threw the easy solutions first before u start buying 200 dollar parts..
Check your lines for no leaks or cuts, matter of fact, spray down the whole back side of the engine while the car is running. see if it dies, if it doesn't..THEN Check your tps, map, and ur iacv and see whats up.

lsjon

Yeah pretty sure ive narrowed it down to the iacv connection, the iacv is a obd2 accord style valve that originally comes on the engine, and its a 3 prong valve, where whoever did the swap rigged it to where the car atleast runs, but its only 2 prongs connected since the obd1 prelude harness is set up for a 2 prong obd1 iacv.

JDogg

the simplest solution is to swap the upper half of hte intake manifold with one from any usdm h22, then you can use a normal 2wire iacv. you cant wire in the 3wire type to an obd1 ecu because the obd1 ecu dosnt send the proper signals to the 3 wire type.

lsjon

for the love of god thankyou jdogg, i wasnt sure if i could get by with just swapping the upper half. You just made my day alot easier.

lude98SH

hmm i think i confused that manifold.


Modified by lude98SH at 4:40 PM 3/25/2008

lsjon

So... i did the manifold top swap. And yeah it was a pain in the ***. I should probbly do a write up for people in the future. But basicly i had to swap the upper plenum manifold studs from my donor h22 manifold, to the f20b. The f20b upper plenum studs are to big for the h22 upper plenum holes. So instead of drilling i just swapped the studs(which is a pain in it self with the lower portion manifold still on the head. Then the usdm h22 upper plenum has like 5 more vacume openings then the f20b, so being i was running out of time i had to rig the vacume setup to get it running. So while i was sitting at home last night i went over the vacume diagrams and hopefully i can get it all going today on my lunch break at work.

Htwentydeuce

sorry for posting on such an old thread, just really needing help. I just bought the h22 top plenum for my f20b. going to use the f20b butterflies just need to know how you went about installing it and what mods you needed to do.. please help!