i have a 1990 siR. which o2 sensor is the primary one?. i have racing headers so there is no place to put one in there. there is a spot on my exhaust to put it but its before the cat its that correct? should i go with a simulated o2? car is running like straight **** any help would be great thanks fellas!

 

done a little searching and found that i need 2 o2 sensors hooked up. will o2 simulators work in my case?

 

Just replace them with O2 and make it run right. Do it right the first time.

 

I suspect you are running OBD0 still. The PR3 and PW0 ecu's both use 2 O2 sensors. They both sample pre-cat. To make the engine run properly you must have both O2 sensors connected and working as they were designed. You cannot splice together, you can't run both sampling all 4 cylinders.

There are a couple of headers, inc the stock one, that will work correctly.

Your other option is to convert to OBD1 (distributor, jumper harness, ECU, 4 wire O2) and only run the 1 sensor.

 

so ur telling me i need a sensor in the headers

 

Yes

 

they are racing headers with nowhere to put it. drill and tap a hole?what would be the best thing to do

 

order an o2 bung from summit racing weld them on and you are good to go.

 

ok i just ordered the bungs. anywhere specific on the header ex. 1,2,3,4 i should place it?

 

do you still have the stocker headers? if so, just look at them, see where the o2 bungs are on the stock ones put the bungs on the same spot on your new headers

 

na i dont have any stock headers. should i put it low where they all meet?

 

The O2 sensors NEED to be mounted where the stock ones are located. If they sample from after the collector(where it goes to 1) your engine will not run correctly, it will run, just too rich or too lean.

If you have a 4-2-1 header that matches the same cylinders as the stock unit then you can add the bungs at the secondaries(the 2 in 4-2-1). But it needs to be the same as stock.

 

how do i put a pic up so u guys can see. ive seen where they are located in the stock header but dont know the correct spot on the racing headers

 

Ok, you asked which sensor is primary??? The one with the green square plug is primary.
The white oval plug is secondary and yes you need both in the upper section of your header. Cylinders 1&4 are primary and 2&3 are secondary. Install your o2 bungs as in my pic, also make sure they are 18mm bungs. Cause the sensors are 18mm. I know summit sells a metric and standard size. Also, the hole on your header thats next to the cat needs to be plugged. get a small bolt and plug it. USELESS on OBD0 cars.

 

no doubt man thanks alot this will help alot. ive never seen o2's that look like that

 

i got the bolt in the one before the cat

 

Well welcome to the JDM b16a oxygen sensors. LOL, no problem. I have 8 full years of experience with honda's and counting. Its my passion!
Look out for my business soon, i am a Honda and Acura specialist. I will post once its opened.

 

This info is not completely correct.

Most 90SiR's (however, not all) have one pre and one post-catalytic converter signal.
On the dash will be an indicator light for the cat functionality. It will light up red, as well as throw a code 1 or 2. (or 43)

This setup is harder to fake, because the ECU is actually expecting a significant difference between sensor 1 and 2 to verify cat efficiency.

The picture ALSCRX is also a terrible setup. No offence dude. But that setup is only reading cyl #3 and #4 properly and maybe #2 a little and #1 not at all. Which is a shame because 1 and 2 are the most prone to fuel mixture and temperature issues.

 

so what do i do man?? please help me out. thanks

 

You are wrong..
CAT efficiency wasn't measured until OBD2

 

ding, ding, ding.....follow this information.

 

Right pod, lower section, there are 2 lights on either side of the ajar indicators.
From the right two, the catalytic converter warning light is the top one.

Gauge cluster pinout can be found HERE.
Cat temp signal is the exact same voltage signal as any other 3V lambda reading.
I would translate it from my jdm manual, but my japanese is a little on the rusty side.

...anything else you wanted to dispute??

 

Anyway, to the original poster...

The best option would be to buy a $2 bung. You can get those from any muffler shop. I happened to buy mine from thermal R&D. (www.thermalrd.com)

Look for the merging point from runners 1+4 and 2+3 (that info was correct) and drill a hole, weld on the bungs at your convenience. I positioned mine simply left and right...because I had a thicker radiator and I wasn't looking for clearance issues.

If you can't get a bung, you can get bolts that have the same fine thread as an o2 sensor has. Cut one in half, and you're ready to go.

Remember that stainless steel headers are notorious for throwing o2 sensor codes because of heat dissipation issues. The same will happen if your sensor is too far down the exhaust line. 4-1 headers have no other choice but to mount the sensors all the way down near the cat...if you want to have any hope of an accurate lanbda signal. You can be lucky...but I had codes all the time.

In that case the best solution is to simply get a heated 3 or 4 wire sensor, and hook it up to any available power source. Preferrable an ignition switched source.
It's a couple of extra wires. But it's the neatest solution.

...or you can just chip the ECU and run open loop

 

i am having the ecu chipped right now. whats this loop about??? thanks man

 

Open loop is just jargon.
It means you are running the car with the o2 sensor disabled and bypassed. So the circuit is "open". Hence open loop, and closed loop for a functional o2 sensor.

You do kinda sorta really need an 02 sensor to tune/chip the car. But wideband sensors are usually heated, and will work fine all the way down the header.