I am using Matco Tools MD9001 OBDII Scan Tool.

a) I have a JWT ecu with the following:
POP Upgrade Package
95-97 SER MT
S3/S4 Cams
R02 + EGR T Rest. Added

b) I also have a stock 99 sentra ecu that came with the car.

The procedure:
Install ecu. Clear codes with MD9001. Pull up codes and compare only INC values under 'I/M readiness'.

Test 1: Stock ECU
codes: PO505, PO335, P1492, P1400, PO443, P1105

I/M Readiness: catalyst mon, evap system mon, oxygen sensor mon, oxygen sensor heat, egr sys mon

Test 2: JWT ECU
codes: PO505, PO335, P1400

I/M Readiness: catalyst mon, oxygen sensor mon, egr sys mon

Tests 3, 4, 5, 6, 7, 8, 9, 10
I continued repeating tests 1 and 2 as above by swapping ecu's and pulling codes. The codes seemed very consistent except for P1105 (stock ecu) which sometimes would show up and sometimes it would not.

The JWT ecu cleared up some codes as shown above. This is a good thing. The PO505 code is for IACV and the PO335 code is for crankshaft pos sensor. These two components will be replaced and therefore should eliminate the codes.

Questions:
1) What I don't understand is if the JWT ecu has EGR resistor, why do I still get code P1400?
2) Why does egr sys mon show up as INC under I/M readiness?
3) Why does Oxygen sensor mon show up even though there is Ro2 program?
4) What is catalyst mon?

Anyone familiar with the I/M readiness please advice. Is there a more consistent way of comparing two ecus?

is your rear O2 rewired? IIRC there is also a little playing with some of the vac lines around the vaccume solinoid (that could be it, just making sure you have your bases covered)

Thanks for the response Brian. The o2 is untouched and so are the vac lines. This is a JDM motor highport.

Thanks for the response Brian. The o2 is untouched and so are the vac lines. This is a JDM motor highport.
you will have to rewire the rear o2 sensor, or put in a 95-97 model o2, you can get the wiring instructions on the JWT website.

your runnin a jdm highport w/ an OBD II ecu????

your runnin a jdm highport w/ an OBD II ecu????

JDM Highport. I have a stock ecu, g20 ecu and JWT ecu. All these ecus are OBDII. I'm trying to compare the JWT ecu and see how much benefits I can get from using it.

Goal: eliminate all codes. So far from my testing the JWT ecu got rid of a few but not all codes. I will experiment with what Brian advised.

you will have to rewire the rear o2 sensor, or put in a 95-97 model o2, you can get the wiring instructions on the JWT website.

http://jimwolftechnology.com/wolfpdf/WIRING98SENTRASR20TO95-97ECUWIREMOD.PDF

hey paul you get that iacv yet??

hey paul you get that iacv yet??

Yes I got it but I have not installed it yet. I was busy doing brakes. After I install it I should lose the idle code.

great thread ive been wondering all this for myself since im going to put a highport in a b14 and still want obd2 compliance

From what I know, you do not need to rewire the O2 sensor, in fact, you don't need a rear o2 at all if you get the JWT resistor.

Based on my tests in the first post, you need to rewire the o2 sensor or just get a 95-97 o2 sensor. YMMV.

UPDATE:

Today I replaced my IACV and retested the ECUs. The JWT ecu throws off only one more code: PO335 (crankshaft position sensor). I wonder why I get this code. I have the stock flywheel. I'll do more testing later.