I got all new exhaust ran from my long tube headers back. There are not emissions laws in my state so I removed the cat in the process. Now my 02 sensor is throwing the check engine light. My buddy was telling me of these things called "o2 simulators" anyone heard of them for our trucks and anyone had any luck with them? I've heard they are like around $30-$40. I've done a little snooping online but I'm not positive what I'm looking for. I've never dipped my hands into learning about o2 sensors and the wiring involved with them.
Universal o2 simulator single output [unv-o2sim1] - $40.00 : O2 Simulator, E-commerce This is looking like my best bet I think? Any responses before I order it?
the ONLY ones with sensors behind cats are California emissions trucks. It should have a sensor before the cat. Make sure your sensor is plugged in and doesn't have a leak. is it the correct sensor? (did you replace it?) RockAuto.com Denso o2 - $60. Toyota dealership same part? $180. what long tube and exhaust are you running? You also need to figure out what CEL code it is. JUST LOOKED AT YOUR BUILD THREAD. MY stock location is before the cat, not on a primary. anyone have a similar setup? The signal mine reads is a mix of all 4 cylinders. Yours is just one. Maybe that is why.
Yea ur header might be the issue. Its not getn the reading from all 4 cylinders. Nam has a good point
if your truck is 0bd2 it has 2 o2 sensors, doesnt matter if its cali or not, if its obd1 it has 1 and you need that sensor to get the right air/fuel mixture. that headder is only reading off one cylinder which kinda sux, i would move the 02 location to the collector where it can read all cylinders.
Bah... Figures... How far down can I relocate the first o2 sensor? Could I put it right next to the second one?
I'd weld a bung in the middle of the 1st pipe after the header. do you have the old front pipe? it should be at least a foot or something in front of the cat. next to the crossmember the o2 wires come from.
all trucks are OBD1. all cali trucks are OBD1 with 2 oxygen sensors. The second ensures the cat is in place and working (basically)
ok well i assumed toyota didnt start monitering the cat until they went 0bd2. learned something new again. anyhow for the op, the closer to the engine the better for the first 02 sensor, i would put it in the collector of the header, where all 4 tubes meet or right after in the first part of the exhaust pipe after the header.
Many pre-obd2 cars have a downstream sensor starting in the late 80s/early 90s. as a tidbit of useless knowledge: OBD1 is technically a california standard starting in 88 or 89 (forgot) which included the downstream O2 sensor. thus you can have an EFI setup pre-OBD2 but not OBD1. almost nobody knows and nobody cares. I don't want to think about how much I'm paying per credit hour to learn such helpful stuff. If you put the second O2 sensor anywhere but AFTER a cat converter, it will probably throw a code. the 1st sensor should read a sine wave (roughly) because that's what the mixture's doing. the cat takes care of all the peaks and troughs of the mixture and makes it level (and in doing so, less CO, HC, NOx) thus the second O2 sensor with a functioning cat will read nearly flatline. If you have the second O2 sensor plugged in without a cat, it may or may not throw a code since the second O2 sensor will read the same as the first and that's not what the ECU wants to see. Depends on how they programmed it, I don't know (or care beyond curiosity) since I don't have a cali truck.
Since mine has both o2's and I do not have a cat installed what should I do about the second one? Should I get the o2 simulator? The first one is the one that does all the adjustments, the second just throws the check engine light, correct?
