Ok, here's the story, I was running a chipped ecu in a B18 and everything ran fine. I was burning a lot of fuel (20mpg highway). I am not running that ecu anymore, and have been running a JDM P30. To try and pass smog, I've switched to a USDM P30, and I threw a CEL 43 (Fuel system). I switched back to my JDM and the code is gone. I know the problem isn't fixed, and I'm going to change my o2 soon.

Now the Question. Is the fuel mapping on a JDM ecu different than that of the USDM? I would assume so, but I thought that the main difference between the JDM and USDM was size.

I know polution is an issue in Japan, like it is here in California, so if a USDM ECU throws a CEL for a bad o2, then why wouldn't the JDM ECU throw the same code when run with the same fouled o2?

 

JDM and USDM ECUs do have different fuel and ignition mapping.
The JDM ECU also has less emissions related checks, I'm not sure but CEL43 may be one of them.

One other thought... a P30 on a B18 is not going to run right anyway, it's for a B16.
P72=B18C1(GSR)
P75=B18b(LS)
screwed=B18C5(ITR) - there is no OBD1 ITR ECU.

 

I agree with Relic1 in that you should match the ECU with the engine. I used a P30 ECU for when I first had the engine, but it wasn't great on emissions and the idle wasn't perfect. When I changed out my ECU and used a wiring harness to match the ECU to the chassis plug, emissions was significantly better and the idle was as OEM as you can get. What engine are you running?

P73 = B18C3 or B18C5

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Relic1 &raquo;</TD></TR><TR><TD CLASS="quote">One other thought... a P30 on a B18 is not going to run right anyway, it's for a B16.
P72=B18C1(GSR)
P75=B18b(LS)
screwed=B18C5(ITR) - there is no OBD1 ITR ECU.</TD></TR></TABLE>

My throttle body doesn't have the secondary butterfly and I'm not running the secondary o2. There are ways of making a B18 run correctly off a P30 and turn an ITR into an OBD1 motor.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by TahitianEG &raquo;</TD></TR><TR><TD CLASS="quote">

My throttle body doesn't have the secondary butterfly and I'm not running the secondary o2. </TD></TR></TABLE>
easy things to go around if you have to.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">There are ways of making a B18 run correctly off a P30 and turn an ITR into an OBD1 motor. </TD></TR></TABLE>
I drive one daily, but I live in illinois not cali.

Depending on where in cali you are... emissions testing will fail you.
If you're lucky enough to be out of the area that tests like hitler ran things then you may be able to get by with chipping the P30 and having it tuned really well.