hi, we all have been talking about j-spec engine, importing j-spec car all the time, but I couldn't find a thread or much information to detail all difference between the two. information such as: ECU? are they using the same ECU? what about AFM? etc.

here are some thing that I noticed after upgrade my GXL to a turbo with a j-spec engine.
1)upper intake manifold
2)BAC: us one can be adjusted, but j-spec won't
3)j-spec don't have AWS
4)ECU? I am not quite sure about this one. I know N370 is used for 89+ TII in US, but I heard that jspec uses N374. anyone heard about this? on my j-spec engine, it came with N374 BAC

therefore, I really want to create a detail table to list all part number for things like ecu, boost sensor, BAC, AFM, etc to distinguish the j-spec and US-spec.

welcome for any idea, which I definitely need you guys' expertise. I think this will be very helpful for all of us.

comments?

 

ECUs different as they run MUCH higher octane gas.

Emmission controls are different too.

I know we've listed the differences before. I'm sure there somewhere on this site or another website.

 

also, I was told that the j-spec ecu has speed limit set in the chip. so, the j-spec ecu won't be useful here since we don't have high octane gas like in japan? and that is why the BAC different, as well?

if anyone knows where the list as vaughnc said, please let me know.

thanks

 

i know in seoul (chuck in seoul, and is that korea?) that the highest they have is like 89octane but its equal to our 93 octane because ours is crappilly rated or something like that, maybe something along those lines is whats up in japan

 

all the FC's we get in NZ are straight outta japan, and they all have adjustable BAC valves on them.........

 

really? I got 3 BACs here from j-spec engine. none of them can be adjusted. wonder that they make some special one? like the engine on my car. that is why I am having problem to get the correct idle rpm. mine desn't even has AWS, and sensor near the tPS. even my spare engine is the same. have anyone seen one like that?

what about AFM. anyone knows about which is which for which model?
like n350 FOR N/A, and N370 for turbo etc

 

hey reted !? do you think you could shed some light on this subject .

 

That's true these days, but wasn't when the FC was made. JDM FC's are tuned to run on "normal gas". If they were tuned to run on high octane gas they'd make more power than US cars, but they don't. They also run fine on our gas, which sure isn't high octane!

 

Not mine, just an empty hole in the side of the BAC...

 

The BAC on my Jspec engine don't have the adjustment screw either. So, anyone know how to adjust the idle on the Jspec engine?

 

Uh, like?
I'm against an NA to turbo conversion in the first place, so I didn't post any replies to this thread...

To adjust idle, you need to adjust the throttle stop screw on the TB under the IC...



-Ted

 

sure, but ECU is tuned to run on " higher octane gas", but the motor isn't. sure it can run with our gas. but when you swap the JDM ecu into your car, I am sure that it won't run smoothly. I tested it.

my another question is that AFM N350 is used for n/a, and N370 is for TII, but can we swap them? like put N350 on TII? according to book, both of them have the same resistence in open and close states, even for intake themosensor.

any one tried that before?

 

sure, that is a lot of work. it took me 2 years to find all parts, and swap them. but I learned a lot though

I do turn the screw to adjust idle, but it seems not working every well. at least it is hard for me. since the AWS is missing on j-spec intake, mine motor just hard to start at cold. I have to keep the throttle open until the car actually runs at normal temp. othewise, it will just died this is very risky. I could flood my engine anytime when I start the car in winter.

does anyone has the same problem?

by working on it, I found more and more interesting differences, and I thing that is helpful to have a table to list all parts between the two, and which is interchangable, which is not. I am sure a lot people out there have j-spec under hood

 

Um, you tune an ECU to run a particular octane, you don't tune the motor...
The differences between the US and Japanese ECU's is all to do with emissions and differences in equipment (that's why it wouldn't run perfectly). But they're not tuned to run only high octane gas. Jap-import FC's run fine on the pump gas over here, but other imports that are specifically recommended by the manufacturer to run on 100-octane gas do sometimes have problems.

 

i have a pair of BAC valves sitting here with the numbers n318 1383000 0140 on them and they have the adjustment screw on them, i have seen a couple of BAC valves on others cars which have a cardboard like cap thingy over top of the screw............

 

I think they're all suppossed to have that cap from the factory, but mine's completely empty.

 

I belive an NA to turbo conversion is only really worth it on a convertible. Finding a T2 as a good starting point makes much more sence. I know this from personal experience helping Brad with the rear end and tranny swap from a T2 to his convertible. Turned me off for doing the swap on my NA (R.I.P)

 

if so, does it mean we have to tune our US ecu to work with j-spec motor or just get a j-spec ecu? does anyone use or know anything about this j-spec ecu?

 

any one know that they are interchangable? like the one with screw to swap with the one w/o screw?

any one knows that what exact number on AFM for 89+ TII? I put a N370 AFM on this j-spec engine, and it just won't start. but engine runs with N350 n/a. but the boost sensor is N370. just wonder

 

Hmmm.. I got the COMPLETE jspec swap from japan meaning all jspec electronics, sensors, and engine, except TPS. I noticed the ECU is N374 but the AFM and boost sensors are N370. My BAC also has N370 and the adjustment screw. I didn't really notice there is much of a difference. My car starts fine when cold, now flooding here.

 

all my BAC has N374 w/o screw. on what model does manu start using N374? or just only on jspec? but it seems not, cuz you got the N370 BAC w/ screw. any one has better idea? when you just finish swap the motor, and ecu, did you actually have to tune the car or just runs as original? when I put this N374 ecu in, it died with the original rpm setting. I didn't continue since I am afraid this j-spec might mess up something else.

any one know why?

 

Mine is an 89 TII RHD and the ECU number is N380. The pump gas here is 98 octane.

 

really

where are you? I mean why your gas is 98? how does it compare with 93 in US here.

anyone knows any differences between 88 BAC and 89+ BAC? can we interchange them, regardless the number?

 

FYI,

US Gas vs. Jap and Euro Gas is as follows

US Gas + 4 = Jap & Euro

So our 93 is their 97.

It's the RON & MON methodology that's different.

 

Yep, US specs on octane is an average of Research and Measured octane numbers.&nbsp Research is always higher; measured is always lower.&nbsp Most countries outside of the US use Research octane numbers which looks really inflated to most US folks.


-Ted