Is a '97 OBD II JWT ECU compatible with a '95 OBD II KA24DE?!?

[MarkEmark]

I've been looking for a JWT ECU programmed for 50 lb fuel injectors and a Cobra MAFS for quite some time right now, and they are few and far between, especially OBD II for a manual transmission...My engine is a '95 OBD II KA24DE. I found one on ebay for a great price (don't even think of taking it, you bastards), but the auction ends in one day so I need a quick answer...

Anyway, the ad description says:

"96 240sx ECU tuned by JWT (Part number E2401-TMF5F) designed to run a turbo on a KA24DE utilizing a Ford Cobra MAF sensor, and MSD 50lbs injectors. Was used flawlessly for about a year in conjunction of F-Max Stage II Turbo kit on a 97 240sx. This mod retails for about $595 at JWT and is setup for a manual transmission drive train only"

So it seems that he got the '96 ECU and had it programmed for his '97 KA-T, but since both '96 and '97 are OBD II I guess that means they're interchangeable?

My question is: He used it on a '97 KA. Assuming my '95 KA is OBD II and his '97 KA is OBD II, would there be any problem running this JWT ecu tuned for a '97 engine on a '95 engine?

I wouldn't think there'd be...

What's strange is that the part number he gives is supposed to be for a '91-'94 (OBD 1) KA...But this must be some sort of mistake because it was used on a '97.

To sum up: Bottom-line, is a '97 OBD II KA ECU compatible with a '95 OBD II KA?!?

Thanks...

[Structure240sx]

all s14's ecu's are compatiable with one another. if you look on jwt's site they show what needs to be done to use it on 95's i beleive with OBDI. only thing is the a/c wire. if you dont car about a/c then there shouldnt be anything to do. check over jwt's site

[:: orion ::]

...and there's nothing to do when putting a '96 ECU into a '95 car.

To run it in a '97, you make a couple wiring moves. But the ECU will bolt right into a '95...but since there are a few missing sensors on the '95 motor, you'll always have a CEL.

Buy it.

- Brian

[MarkEmark]

Nice, I got that sucker for $335, and should make all my money back when I sell my existing ECU...

It's too bad that bigger fuel injectors/MAFS/fuel rails cost so damned much.

I might start a separate thread on this...but is it possible to use 550 cc side feed injectors instead of the 50 lb/hr (525 cc) top feed injectors with the JWT ECU programmed for 50 lb/hr fuel injectors? Being able to use side feed injectors would save the hassle of changing the fuel lines/rails and would probably be a cheaper route, especially since I believe structure240sx is still selling his at a good price..

Is the 25 cc more for each fuel injector going to make that much of a difference? Would it just run richer? I could always lower the fuel pressure a couple of psi to make them flow 525 cc/min. BTW, I know there's some resource out there showing increases/decreases in cc/min flow vs. increase/decrease in fuel pressure in the rail

[WDRacing]

My buddy ran 310cc injectors on his RB20 which is only programmed for 270's. It was a tad rich, but no smoke in the exhaust.

You may be able to trim the base fuel pressure down a lb or 2 just to compensate.

[:: orion ::]

To determine new injector flow:

Take the square root of the new base pressure diviided by OEM base pressure.

So to get 555's to run like 525cc injectors...lower the base pressure ~4psi.

Take the square root of ( 39.5 / 43.5 )...which is the square root of .908...which equals .953.

95.3% of 555 = 528cc.

So lower your base pressure ~4psi, and you'll be set.

Typically, I don't like reccomending lower base fuel pressure...but try it...4psi isn't that much.

- Brian

[MarkEmark]

Yeah, I don't really like the idea of lowering it 4 psi either because it could aversely affect the atomization of the fuel/the spray pattern...

Realistically, would it really run a LOT richer if I kept the fuel pressure the same and used 550 cc injectors (not 555 cc)? What about just lowering it 2 psi instead of 4? I guess it would, and given the inherently rich nature of JWT's programs, I'm not sure that's something I want...

I guess when all's said and done it'd only cost $100 more to go top-feed, which seems worth it to have the fuel curve more optimized.