Thread: sputtering after new o2 sensor

i installed a new ebay header on my car and got me a new denso 4-wire o2 sensor to replace my worn out 3-wire bosch that came with the car when i bought it back in 2001.

the car feels more responsive and idles really smooth, all was working fine the day i installed it but the next day i drove it to work on the highway and it started to sputter a little bit. i pulled off to an off ramp cause it was my exit.

when i accelerated from the stop sign it felt the hesitation right off the bat and im not to happy as i had no issues with it prior. just a junky stock exhaust manifold. now i have hesitation and not sure what is causing this issue.

i was reading a little bit and alot of different forums state to disconnect the battery so that my ecu is forced to relearn with the new sensor. I have the battery disconnected right now and will reconnect it at 5pm when i get off work today.

the denso has 4 wires blue, white and 2 blacks.

blue wire - signal wire
white wire - ground to ecu
black wire - 12v+ when the key is on
black wire - grounded to the engine block

the 3 wire sensor had signal connected to a white wire
power connected to red
ground on black
all i did was add an extra ground to the heater side of the sensor and spliced the new sensor to old sensor's harness connector.

i know that i got it wired correctly, im sure if i didn't hook it up right i would of fired the ecu.

any input from the community would be greatly appreciated.

http://www.sr20-forum.com/information-library/4595-regrounding-o2-sensor-11.html

Was the header reamed to match the exhaust ports on the VE head?

I doubt that is the issue at hand. Mine hasn't been ported and it runs fine. Likely an issue with regrouping and Ecu learn.

so i think my next plan of action will be to reground the ground wire going to the ecu as the new ground that i added yesterday would only be for the heater circuit. I am not sure how that ground coming from the ecu works but i sure hope to not ruin my ecu.

i will cut that wire and rewire it to the ground on the engine block, the cut wire going to the ecu will just be left unplugged.

is this correct?

Are you sure you have the correct 02 Sensor for that setup. All this info has been confirmed through Bosch. Part number is #15727.

i bought a Denso sensor for a 1995 g20t 4 wire and not a bosch. i will have to check the difference between the two of them but its still for sr20de engine/ecu.

Part No. 234-4650 denso o2 sensor - not the correct one

i am not sure but i ordered the o2 online at advance auto with a 25$ off coupon and got a great deal. hahahahahahahah come to find out now i have to go and buy the correct fit.

i am not finding what make/model the o2 sensor i have is for, sigh

i guess i off to the autoparts store to buy the bosch sensor.

thanks all for helping me thru this ordeal.

No problem man. Better off this way. Atleast you won't risk frying your Ecu.

****ISSUE RESOLVED****

got the 15727 sensor and all is normal now - super smooth idle with no hesitation at any speeds.

new sensor bosch 15727


spliced harness all hooked up


tied the ground to the intake manifold where the rest of the ecu grounds are connected.

Sweet dude.