Puppetmaster

iTrader: (48)

That's what I thought initially as well, but on EC-238 & 246, in the Specification Data table and the diagrams, it says that the voltage has to change more than 5 times within 10 seconds and it should go below 0.3V at least once and above 0.6V at least once within that 10 second span. This is why I think it won't just register a constant rich condition because the signal from the sim is constant.

03maxima1

iTrader: (13)

I might just do that but either way I have to order one and my install is for tomorrow. So I will have to drive the car without one if that is what I chose for a week or so.

Puppetmaster

iTrader: (48)

Or just take it someplace else....

Puppetmaster

iTrader: (48)

I've been driving around for several weeks with a CEL and no secondaries plugged in....

upstatemax

iTrader: (15)

I see your few weeks and raise you eight months on a CEL for a plugged off EGR.

03maxima1

iTrader: (13)

Why? I thought you sold your Y-pipe. Did you not go back to stock?

steven88

iTrader: (28)

ALL IN THEN!!!!

Chaser

Just when I thought all those years of basic electronics meant something. When I get my headers in march I'll have to PM one of you guys for the Diagram or schematics on how to hook up the O2 sim. Sounds alot better than welding and re-welding if I want to install new exhaust parts. thanks for all the info.

BlackBIRDVQ

iTrader: (15)

ECU will not rely on the 2ndary 02 sensors for Air fuel control. After the excess fuel from the engine is burned in the cat the air fuel ratio will not be accurate enough for the rear 02s to read it. One of the MAIN functions of the CAT is to burn off HCs- excess fuel. After that is said and done, the rear 02 will read that there is really no problem with the A/F.

ECU has its safe mode map for primary 02 maulfunction. It relies on predetermined timing and fuel maps based on engine load calculations from the MAF, and throttle position- based on the TPS sensor. So in theory you could drive with no 02 sensors, but your gas mileage and power output will not be at its optimum leve.

steven88

iTrader: (28)

what happens if your running a test pipe?

Puppetmaster

iTrader: (48)

Yeah, we were kinda just kicking around the thought of "what if" the primaries went out and the O2 tried to use the secondaries, but they are simulated. Thanks for the info though.

chris'smax

iTrader: (3)

does this occur in open loop also? I would assume so if it is in a "safe" mode

chris'smax

iTrader: (3)

when i did mine i only had to relocate the front primary o2 sensor by getting a new o2 bung welded on in a different spot in order to clear the ac compressor.

Puppetmaster

iTrader: (48)

http://forums.maxima.org/showthread.php?t=455513

NisMo-Max

iTrader: (40)

I have a ? When i had a Stillen Y pipe. My secnondary o2 Through a code, because the o2 sensor failed. But when i had an 02 simulator installed, it got rid of the p0140 code but then another 1-2 codes appearing with something like "Heated Oxygen circuit" i dont recall what it was exaclty but something with Heated in it. but will i have the problem of another code like that one if i do put a sim when i get headers?

upstatemax

iTrader: (15)

do you have the o2 sensor still hooked up?

If you do, the sensors have heating circuit and that can still go. Thats why you need to keep the sensor hooked up to the car.

NisMo-Max

iTrader: (40)

Well i dont have the problem now, because i sold the y pipe, But i had to buy a new o2 sensor because the other was was dead. So you mean when i had the o2 simulator on i was suppose to take of the o2 sensor off the y pipe and just hang the o2 sensor somewhere?

upstatemax

iTrader: (15)

Thats what I do with them for my headers...

They are tied up the the tube that you use to add tranny fluid.

But yes, if your heater cir goes, you need to get another sensor (as far as I know). The SIM does not simulate the heater cir.

BlackBIRDVQ

iTrader: (15)

ECU will still not look at the 2ndary 02 sensors for A/F ratio controll even if you have a test pipe. It doesn't know the test pipe is in there and it relies on the preprogrammed logic inside the ECU. The ECU is programed to look at oscilations from the front 02 sensor and compare them to the rear 02 sensors. It looks how much FUEL is in the exhaust before the cat, and how much is left after it leaves the cat. After that it calculates if the cat is properly working, if its not it throws a code for efficiency below threshold- PO420 for rear cat and P0430 (only on the Cali spec 3.0Ls and all 3.5Ls that have the front precat) for the front cat.

If the cat works properly there will be very little fuel left over in the exhaust after it leaves the cat- bout 30 Parts Per Million of HydroCarbons is a good number for a brand new car with a good cat at idle. 30 PPM of HC would mean that the car is runing dangerously lean to the ECU if it relied on the rear 02 for air fuel ratio control, and it would command lots of gasoline to be dumped into the engine to bring up the A/F into stoich area.

If the primary 02 fails to operate properly, ECU will go into limp or safe mode and use preprogrammed A/F and timing maps inside the ECU. Its similar to the effect that 4th gens have when the knock sensor goes bad- and I hope I don't have to explain that to anyone. Your power will not be 100% there, and your gas mileage might be different as the feedback system is no longer responding- due to the 02 sensor not working.

ECU does not rely on 02 sensor readings in open loop operation, it looks at them but doesn't acutally use them for any fuel enrichment. Once the car reaches certain engine temperature the ECU switches over to closed loop operation and uses the feedback system- basically 02 sensors which send back info to the ECU (if the sensors fail the ECU goes into OPEN loop and safe mode). ECU tends to switch back n forth from OPEN to CLOSED loop depending on engine load and throttle position. If you are going WIDE OPEN THROTTLE the ECU automatically goes into OPEN loop mode, it looks at MAF readings and throttle position readings, at the same time looks at knock sensor values and dumps XXX amount of fuel in the engine. This is why piggy back computers work so well under WOT mode, as you modify the WOT MAP and free up HP by eighter adding or subtracting fuel from the MAP. Its VERY hard to tune a CLOSED loop operation on a piggy back as lots of factors have to be taken into consideration when tuning. At the same time only time you would be tuning a closed loop operation is if you are using larger injectors or MAF sensor in order to keep the A/Fs at proper mixture, get optimum gas mileage, emissions and throttle reponse. Anyone can tune a WOT MAP, but its ALOT harder to tune closed loop maps...

I won't go much more into detail on the closed loop and open loop operations.

03maxima1- I got your PM bout the install, I'm sorry to hear bout all that. I will give you a halla sometime, if not I will reply back to your PM. At times I am really bussy with work etc and dont respond right away.

03maxima1

iTrader: (13)

I Appreciate it. Give me a call when you get a chance. Maybe you can help me out with my problem.
Thanks