Thread: OBD2 readiness issues

Changed title to include broader subject.

Has anyone made an EGR simulator for these cars with any success in getting a "ready" from the OBD2 readiness?

I have this G20 project I've been working on and I can't get the O2, Cat, or EGR to say ready. I can have 2 "not ready" tests to pass the state I/M. The car has over 700 miles on it with temporary registration and it still will not say "ready" for any of these. My car has never had that issue before, so it leaves me

So I have decided to go a step further and build an EGR simulator. Something that will show EGR temp voltage increase when the EGR solenoid gets power. Nothing really fancy, kinda ghetto actually. But I only need this thing to trip "ready" once so the car can get registered.

By using the stock EGR temp sensor, 66K ohm resistor, and a 5-pin relay, I think I can get it to work... or at least I hope I can.

My car says EGR ready the first time I start it, but for some reason this P11 with a 97 computer will not. Interesting. I have tried plugging in the resistor into the Temp sensor connector, as well as just leaving the Temp sensor plugged in. No CEL is illuminated, but readiness will not happen.

What have you guys experienced with OBD2?

Guy on g20.net is having the same problem. Found this info for a b14:


There is a Drive Pattern which will set the monitors, but it varies from one vehicle to another.

"I found that there is a Nissan Technical Service Bulletin 98-018C which contains the drive patterns for certain vehicles including the 200SX SE-R and the Sentra/200SX GA18. I joined AllData (Automotive Repair, Auto Recalls, Automotive Software & TSB's - ALLDATA) and downloaded the drive patterns for the 200SX SE-R. It works, but you must follow the directions EXACTLY. That means starting with a cold car and driving as instructed. I only needed to have less than three monitors set, so I started with a cold car, drove to a nearby expressway, and started with #4. It set the 02 Sensor and Catalyst in one pass!"


Try this:

1. Engine coolant less than 158º. Start and idle 1.5 min.
2. RPM 1800-2200, AC ON, constant load*, 3 min.
3. THEN 50-59mph, 2000-2800rpm, constant load*, 1.5 min.
4. Idle for at least 10 min., then switch off, then restart
5. IMMEDIATELY 50-60mph, 4-th Gear, >3000rpm, 3 min.
6. THEN Steady State Cruise 53-58mph, 5-th Gear, 2500-2700rpm, no deceleration**, AC ON
7. Downshift, decelerate no gas at least 5 seconds, then idle 1 min. in neutral

* I assumed it is constant load, but the instructions say "B/F SCHDL 1.5-1.7 msec" for #2 and "2.0-3.0 msec" for #3.
** No deceleration for more than 3 sec. or you must start over with a cool car.



"The car does not give any visual indication about the Readiness Test, so I used my EASE Diagnostics OBD-II program for my laptop computer. It plugs into the OBD-II port under the dash and reads out, among other things, the Readiness status. I drove through the drive pattern with it connected, and could see whether the sensors were set.

On my car, after the readiness tests are set, when the engine is turned off and turned back on, those three sensors read Not Ready again. I had to go through the pattern, drive directly to the test station, and leave the car running through the entire emissions test."

I did exactly that. Nesluopetan is the owner of the car, but I'm doing the work on it. I am going to redo this drive cycle a few more times with my homemade device to see what happens. It is pretty simple, but allows the ECU to see a temp increase at the sensor as soon as the EGR solenoid is commanded to open the EGR valve.

Instead of a gradual increase in voltage though, this simulator will have nearly instantaneous response. Hopefully that doesn't make the computer mad.

This car has been driven around town, freeway, 45mph consistently ever since we got the SR20DET in. Hell, even with the old DE it never said ready. We were actually trying to figure it out when the engine spun a rod bearing.

Ok, some news with this car. The EGR sim is working, but the EGR solenoid does not receive power from the computer. Seems the computer uses a few readings to command EGR to open.

Coolant temp
Engine speed
Maf voltage

The JWT computer has modified MAF readings, and I think this could be causing some issues with the EGR system going "ready". But who knows.

I decided after much frustration today to swap computers. I took the ECU from my car and swapped Eproms with the G20's JWT ecu. Took the car for a spin, and the car now says ready for the Oxygen sensor. The only things not ready are the EGR and the Catalyst. Which means the car will pass. Wow.

I am going to get confirmation tomorrow that the computer is the issue. If we swap things back and the computer won't go ready, then we know that this is a ECU problem. Or perhaps something is different between the computers. Perhaps this is why only some people experience issues when trying to get OBD2 readiness on these cars.???

Is it a g20 or b14 ecu?

I am not sure. All I can tell you is my computer has a Red nissan sticker on it, where the G20 has a black sticker.

car got registered today. But what a pita. I guess I'll just have to loan my friend my computer in order for him to pass every year.