[SuperRunner]

I have converted from OBDI to OBDII. For some reason my car did not come with heated O2 sensors, but pretty much every other car did. My question is, could this mess with being able to control my A/F's?

I am running a MAP-ECU V2 with and O2 simulator, and a Zeitronix WB that has an analog output, and then a single stock O2 sensor in the downpipe. I have tried plugging these into the 3 oxygen signals into the ECU, but it doesn't do anything.

At idle I can't get it to run anything but 12.7, no matter how much I lean out the mixture. I need to get this to pass emissions and a 12.7 just won't cut it.

I need to know if the OBDII ECU also needs to know if the O2 sensor is even there by sensing the heating element.

And then there is the EGR temp sensor. On most vehicles I have worked on, this will cause a loss in gas mileage and cause the engine light to go on. Is that the case for this?

 

[Josh S]

what car/OBD2 ecu are you talking about? Does it run ok with the MAF and the OBD2 ECU?

 

[SuperRunner]

I am running map-ecu, but if I did have the MAF, it would probably run just fine.


I also just came across this thread by accident, was searching for decent scan tools that work with toyota.

Seems that if the OBDII ecu cannot sense that the heaters are working, then it will cause the engine to run rich at idle.

http://www.supraforums.com/forum/showthread.php?t=175226

 

[Josh S]

Correct, so do you do an obd1 to obd2 swap for a 2jzgte? If so you need to add an extra ground pin the the ECU harness for the O2 sensor heater circuit, otherwise the heater will never turn on and the ECU will think that the car is running lean during closed loop operation and dump fuel. Some more info about exactly what your setup is would help me/others give you better suggestions.

 

[SuperRunner]

I am a NA-T conversion. 1994 2JZGE with a 1996-newer 2JZGE OBDII ECU. I am running a MAP-ECU version 2 which is why I chose to run OBDII, otherwise I would have to run karmen vortex.

My paticular harness doesn't use heated O2 sensors(wierd), but I have already added wires for the heaters. I will add 2-6Kohm 10watt resistors as to trick the ECU to think they O2 sensors are connected.

 

[Josh S]

So the actual o2 sensor doesn't have a heater built into it? Are you sure that the stock o2 sensors are working and reporting back to the OBD2 ecu? AFAIK if the ECU doesn't see the heater circuit connected it will just throw a code, but the closed loop feedback will still work ok. at least this is true of the 2jzgte obd2 ecu. If your stock o2 sensor has a heater you could try to wire it up so that there is power to the heater circuit at all times, I ran mine this way for awhile before the missing ground in the heating circuit needed for the obd2 ecu swap was discovered.

 

[SuperRunner]

According to the link I gave above, if the heater circuit is not connected, it will no longer read the O2 sensor and will run rich at idle.

I have tried connecting stock O2 sensor, O2 simulators as well as other O2 sensors. Nothing works. I have just purchased the proper 10W resistors, and I am going to simulate the heaters.

 

[Josh S]

no that's not really what the link says. Here is what goes on, if the o2 heater is not connected the o2 sensor cannot measure the AFR and report an accurate value to the ecu, when the heater is off and the o2 sensor is cold, it will report a lean mixture no matter what, the ecu in turn dumps fuel to try to correct what it thinks is a lean condition.

Now in addition, if the ecu does not see the heater circuit connected it may throw an error code, however this in itself does not affect the AFR.

You cannot connect an o2 simulator to the primary o2 input of the ecu and expect it to work, the ecu requires a real working o2 sensor be connected for closed-loop operation.

You say you have connected the stock o2 sensor to the ecu, but without it's heater working it cannot report accurate results to the ecu.

Are you sure you have connected a properly functioning o2 sensor to the primary o2 sensor input on your obd2 ecu? This is what you need to make happen.

 

[cwtt]

Josh S is correct as far as a TT setup is concerned. I have no idea if a NA ECU will respond the same. When you post in this forum, people are going to assume you have a GTE setup.

You should try the NA section too if nobody knows the answer here. They might be able to help you better.

 

[SuperRunner]

Ok, I elimated all codes except for a cam position sensor code which I assume is the crank angle sensor. Being NA, I do not have this sensor and will probably have to add it.

Anyway, I don't get codes for the O2 sensors at all and all seems to be fine there. I will now take this over to the N/A forums as I have exhausted the O2 scenerio.

Thanks for your help.