o2 sensor not sensing??

[fiatmonkey]

Hi,

I recently replaced my stock exhaust on my FI car with a header and exhaust with no cat. The header is a 4 to 1 with an 02 sensor hole near the end where it meets the exhaust. I installed the sensor here.

I added a short extension wire to hook up the o2 sensor as its a little bit farther away now. However my gas/fuel mixture doesn't appear to be correct anymore. I unplugged and plugged the wire to the sensor a few times but no change to idle, etc.

I have had a similar setup before but don't recall if I had an 02 sensor or how I controlled mixture.

Any ideas? The o2 sensor is only about 1 year old.

Thanks,
Tim

 

[Matthew]

The sensor does not control mixure at idle, full throttle or during warm up. Back probe the signal wire at the ECM and check voltage with the engine warm at 2000 RPM. The voltage should fluctuate from approximatly .2V-.8V a few times a second if everything is working properly.

 

[ArtBasement]

Not hot enough?

I recently replaced my stock exhaust on my FI car with a header and exhaust with no cat. The header is a 4 to 1 with an 02 sensor hole near the end where it meets the exhaust. I installed the sensor here.

Could be your O2 sensor is not getting hot enough with the new exhaust. It's much further down the stream now. I have the same exhaust set up as you, and I installed a heated O2 sensor (3 wire) from a Mustang 5.0. Cheap and fits right into same thread. I took the 12v from the fuel pump.

When the heating element went bad, I noticed it immediately, both in mixture read out on my A/F meter and engine performance.

 

[fiatmonkey]

Thanks Matthew and Erwin.

I will do some testing before I run out and buy a new sensor but I also thought it might be a result of the sensor being farther down stream.

Erwin - Your replacement sensor was from what year mustang do you recall (or does it matter?) and it is a down stream sensor right?

-Tim

 

[lookforjoe]

Thanks Matthew and Erwin.

I will do some testing before I run out and buy a new sensor but I also thought it might be a result of the sensor being farther down stream.

Erwin - Your replacement sensor was from what year mustang do you recall (or does it matter?) and it is a down stream sensor right?

-Tim

Most 3-wire sensors are mounted much farther downstream than the single wire. It doesn't really matter what application, as you will need to add wiring to the heater element connection either way. Normally the ground of the heater element is pulsed through the ECU during initial warmup to prevent damage to the thermistor. That may be why Erwin's went bad.

TIM - do you have AC & what header did you use if so?

 

[fiatmonkey]

Most 3-wire sensors are mounted much farther downstream than the single wire. It doesn't really matter what application, as you will need to add wiring to the heater element connection either way. Normally the ground of the heater element is pulsed through the ECU during initial warmup to prevent damage to the thermistor. That may be why Erwin's went bad.

TIM - do you have AC & what header did you use if so?

Hussein,

Thanks - I had AC but removed the pump along with other gear as it never worked and don't need it here. And the header wouldn't have fit around the pump and alternator setup sorry - I know you like your AC

 

[ArtBasement]

Erwin - Your replacement sensor was from what year mustang do you recall (or does it matter?) and it is a down stream sensor right?

It doesn't matter exactly, but I used a '90 Mustang. I don't think Mustangs have a down stream O2 sensor; only upstream AFAIK.

 

[fiatmonkey]

It doesn't matter exactly, but I used a '90 Mustang. I don't think Mustangs have a down stream O2 sensor; only upstream AFAIK.

My old o2 sensor checked out ok so concluded it must be simply to far down stream. I decided to get a 3 wire heated element sensor for $30 at AZ. It makes a huge difference at speed - rpm over 2k. My idle is actually a tad better but I know I need to re-turn it some.

Thanks all,
Tim