JDM F23A intake manifold

[gsrteg]

(PROBLEM SOLVED ON PAGE 3)

Hey guys, I just purchased a JDM F23A engine to do a swap on my 99 Honda Accord LX 5 speed. I noticed the design on the JDM F23A Intake manifold was exactly the same on the surface, but was unsure if the internal volume design was the same; but I decided not to use/switch my US version intake manifold over. However I did swap over the US exhuast manifold, fuel rail (the JDM banjo bolt was mounted differently compared to the US version), US version throttle body, and necessary sensors. I did keep the JDM injectors on the JDM manifold because the US ones didn't fit into the slots.

Okay, so...

After I hooked every thing up and cranked the car (Yes it cranked on the first try), the idle is now fluctuating back and forth from 800 RPM to 2000 RPM. I recognize the problem, because a while back I had a vacuum leak on my original F23A4 engine. But this time around, I was trying to figure if the JDM Fuel Injectors could be what is causing the jumping idle? Can anyone help me?

I installed a new OEM honda throttle body gasket, I cleaned the IACV (but just with Q-tips and might have to go back and clean it again), and I double checked all my electrical plugs. Any help would be great.

 

[gsrteg]

And I made sure I bled my coolant to extract all the air bubbles through the bleeder valve on the thermostat housing. But still, I have the fluctuating idle. Its annoying the crap out of me. I'm gonna try spraying carb cleaner around the intake manifold to find a vacuum leak.

 

[Russianred]

JDM manifolds may have what's called a FITV (Fast-Idle Thermo Valve). This also is the cause of surging, idle fluctuation problems - but don't quote me on it. Personally, I have found this to be the MAIN cause of suring idle with 5thgenaccords, I would do more research on manifold differences between the USDM and JDM manifolds of 6thgenaccords, primarily the presence of this FITV I mention. Good luck.

Try looking for any vacuum leaks, and actually clean the IACV with carb/brake cleaner, not just q-tips. Spray that stuff in it and let the crap leak out onto a towel - you'll see the dirt.

 

[Pizzaman]

i swapped the manifold, injectors, fuel rail, sensors, exhaust mani and o2. it worked fine minus the TPS and MAP plugs were reversed. once i fixed that it ran like a champ.

change everything to US spec you should be golden...

 

[gsrteg]

i swapped the manifold, injectors, fuel rail, sensors, exhaust mani and o2. it worked fine minus the TPS and MAP plugs were reversed. once i fixed that it ran like a champ.

change everything to US spec you should be golden...

Yea, I should've just changed it over when the motor was out... crap. I just realized how tight the space between the Intake Manifold and the Firewall is. Im gonna take pics soon.

 

[gsrteg]

JDM manifolds may have what's called a FITV (Fast-Idle Thermo Valve). This also is the cause of surging, idle fluctuation problems - but don't quote me on it. Personally, I have found this to be the MAIN cause of suring idle with 5thgenaccords, I would do more research on manifold differences between the USDM and JDM manifolds of 6thgenaccords, primarily the presence of this FITV I mention. Good luck.

Try looking for any vacuum leaks, and actually clean the IACV with carb/brake cleaner, not just q-tips. Spray that stuff in it and let the crap leak out onto a towel - you'll see the dirt.

I'm gonna try cleaning the IACV again with carb cleaner again.

 

[Pizzaman]

Yea, I should've just changed it over when the motor was out... crap. I just realized how tight the space between the Intake Manifold and the Firewall is. Im gonna take pics soon.

thats what i was thinking when i did mine. it is tight as hell back there and not going to be easy but GL.

 

[Michael_accord]

The runners are the exact same thing, only difference i saw was the jdm injectors looked skinnier than the usdm. As for your idle issues idk. I would just swap the top plenum over and you should be golden. Its not hard. good luck

 

[HollywoodHam]

When I first did my h23a swap (before the manual swap), my car would idle low at stops then cut off. I changed the fuel rail, injectors o 750 cc (which u may not need to go that high), sensors manifold and tps, that had her running like a Jamaican track star...

 

[Valet]

You wanna why it appears the same as the USDM ones?

Because there is no JDM F23

However I find it weird that the injectors didn't fit. So there is some difference for whatever reason.