I'm installinga LC Engineering header tomorrow and from everything I read, I should expect my CEL to go on as the O2 sensor will be located too far downstream for it to read properly.

I understand that a heated (4 wire) o2 sensor is the remedy.

I'd prefer to go with a 88-89 4Runner Denso 4 wire O2 sensor to minimize other issues with universal or non-OE (i.e., Bosch).

I've searched up and down here and on Google for over an hour and although I found lots of information, I am unclear of the following...

One of the wires will go to the existing stock single o2 sensor lead (which color on the 88-89?)

According to LC using a Bosch universal, there are two grounds and a heated wire that goes to a switched circuit.

Would the same be true if I use the 88-89 sensor? I saw schematics (that I'm not the best at reading) suggesting a second wire going the ECU.

I'm super confused. I just need to understand what color wire goes to what.

Thanks in advance!

 

Thanks to 4Crawler's page, I think I found my answer:

-Blue Wire goes to the original Black signal lead
-White Wire goes to Ground
-Two Black wires (doesn't matter if reversed):
*Switched 12v for heat element (draws 3-4 amps)
*Ground

 

I've never had a 02 fault issue on my 86 with the same header.

I just the factory Denso sensor. Plug and play.

EDIT: just saw in a different thread you say they put the sensor at the cat?
This is not correct for a first gen. Mines at the Y of the 3 and 4 cylinder.

 

Yes, mine will go right in front of the cat.

 

The O2 sensor goes there if you have the OEM header. He installed the LCE header, which relocates the O2 sensor bung closer to the CAT, hence his question.

Stanz - this is interesting - I never came across this info until now and I have had the LCE header and pro flow exhaust for 4 years. I've had some close calls with smog in CA and both times they tell me to try and get it hotter and test it immediately if possible - wonder if this is why (I am running the non heated O2 sensor....).

 

Sounds like the same issue.

I'm a geek about clean installation so I found the female plug end and pins here to make it all clean and plug and play in the future:



http://www.chasebays.com/product/con...r-4p-connector

 

I had the same issue that was completely resolved by installing a heated O2 sensor. I purchased the cheapest universal sensor that came with the necessary flange adapter for toyota.
A document such as this hiflo.com.au/pdf/O2%20sensor%20wiring%20colour%20codes.pdf‎ can assist if you acquire a sensor without a wiring diagram.
I connected the heater power line through a relay using the Idle Air Control (old style, not on throttle body) power line as a trigger.

edit- It appears that the link won't work. You can find it if you google search "O2 SENSOR WIRING COLOUR CODES"

 

Awesome to hear. I will go the later gen OEM route, but do the same wiring. Thanks for sharing!

 

I just ordered off of Amazon. Fits a 1993 4Runner and it mates up to the harness plug I ordered from Chase Bays. Hoping this all does the trick.

 

My bad guys I got the Downey header. Sorry

 

Update: I have the header installed and the heated 4-wire O2 sensor installed. It's running better than ever. No issues, no CEL. Super easy install for the O2 sensor. See my build thread for pics.