what if i,,,and keep drive..?? - The Ford Focus Forum

**focusonfocus** · 11-01-2009, 05:59 PM

i disconnected front oxygen sensor to test see if my car runs well or not..
apparently, runs better..
but will this damage car??

**Spyder** · 11-01-2009, 06:05 PM

If you disconnected your front oxygen sensor, you car will not run any better. It should run worse if your front O2 sensor is doing it's job.

**focusonfocus** · 11-01-2009, 06:25 PM

it runs better, so i guess o2 sensor is not doing its job..
i replaced front o2 sensor 6 months ago, so something must be wrong with wiring..or if there is 2nd sensor somewhere..

**locdowg7** · 11-01-2009, 06:28 PM

Why did you replace the sensor? Was it thowing a code?

**focusonfocus** · 11-01-2009, 06:30 PM

Quote:

Originally Posted by locdowg7

Why did you replace the sensor? Was it thowing a code?

Q. what year is my car??
A. 2000

should throw code..

**Spyder** · 11-01-2009, 06:47 PM

No, he is asking why you replaced the sensor in the first place, and if you replaced it because you got a check engine code...

**focusonfocus** · 11-01-2009, 06:55 PM

because i never replaced sensor before and threw out 2 codes related to o2 sensors..
after both got replaced, no more code..

but now i m having misfiring issue when engine is cold..
i thought msd coil pack and wires but now i m with oem stuff and doing same thing..
disconnected front o2 sensor and cold start, no more misfiring and cars runs fine..

**Zoomer69** · 11-01-2009, 08:08 PM

I highly doubt the o2 sensor has gone bad again.

First of all, a bad o2 sensor would have thrown a code, just like before. Bad wiring would have also caused it to throw a code for a bad o2 sensor.

Secondly, the o2 sensor doesn't even begin to function until the engine is warm, and therefore the sensor itself is warm. The motor is working from its cold-start tune (which is a richer tune than normal) until the o2 sensor is hot enough to begin working.

Also, the engine goes to that cold-start tune when the o2 sensor is unplugged as a fail-safe, so the engine doesn't grenade itself from detonation from running lean.

You might want to try this again after unplugging the computer and letting it sit (to clear out the computer's memory). Try it once with the o2 plugged in, and if it misfires, try it again with it unplugged. You could also try it with a known good o2 sensor in its place, though I doubt that would change anything.

My assumption is that something else has gone wrong - that some other sensor (MAF, coolant temperature sensor, etc) is giving faulty data to the computer until the o2 sensor light-off occurs.

**focusonfocus** · 11-01-2009, 08:14 PM

i gotta unplug sct chip first to get engine code..
because this sct chip is keep clearing code..

disconnect ecu, not battery??

**focusonfocus** · 11-04-2009, 09:54 PM

oh ****..it was focussport sct chip i had it for 5 years..
1 pin on sct chip looks bit weird..running hot or shorted or something..

but now put back o2 sensor back and ran for 2 days now and the problem is not there anymore..
car is not fun to drive anymore without chip but runs better at least..

11-01-2009, 05:59 PM	#1 (permalink)
focusonfocus Senior TEAM Member Join Date: Jul 2004 Location: toronto, on Posts: 4,176	what if i,,,and keep drive..?? i disconnected front oxygen sensor to test see if my car runs well or not.. apparently, runs better.. but will this damage car?? __________________ Advanced MECP certified mobile installer 2000 Kona Dirt. www.cardomain.com/id/focusonfocus

11-01-2009, 06:05 PM	#2 (permalink)
Spyder TEAM Member Join Date: Dec 2008 Location: WI Posts: 314	Re: what if i,,,and keep drive..?? If you disconnected your front oxygen sensor, you car will not run any better. It should run worse if your front O2 sensor is doing it's job. __________________ My 2002 ZX3 with tasteful mods is for sale! PM me if interested!

11-01-2009, 06:25 PM	#3 (permalink)
focusonfocus Senior TEAM Member Join Date: Jul 2004 Location: toronto, on Posts: 4,176	Re: what if i,,,and keep drive..?? it runs better, so i guess o2 sensor is not doing its job.. i replaced front o2 sensor 6 months ago, so something must be wrong with wiring..or if there is 2nd sensor somewhere.. __________________ Advanced MECP certified mobile installer 2000 Kona Dirt. www.cardomain.com/id/focusonfocus

11-01-2009, 06:28 PM	#4 (permalink)
locdowg7 Junior Member Join Date: Jun 2009 Posts: 84	Re: what if i,,,and keep drive..?? Why did you replace the sensor? Was it thowing a code?

11-01-2009, 06:47 PM	#6 (permalink)
Spyder TEAM Member Join Date: Dec 2008 Location: WI Posts: 314	Re: what if i,,,and keep drive..?? No, he is asking why you replaced the sensor in the first place, and if you replaced it because you got a check engine code... __________________ My 2002 ZX3 with tasteful mods is for sale! PM me if interested!

11-01-2009, 06:55 PM	#7 (permalink)
focusonfocus Senior TEAM Member Join Date: Jul 2004 Location: toronto, on Posts: 4,176	Re: what if i,,,and keep drive..?? because i never replaced sensor before and threw out 2 codes related to o2 sensors.. after both got replaced, no more code.. but now i m having misfiring issue when engine is cold.. i thought msd coil pack and wires but now i m with oem stuff and doing same thing.. disconnected front o2 sensor and cold start, no more misfiring and cars runs fine.. __________________ Advanced MECP certified mobile installer 2000 Kona Dirt. www.cardomain.com/id/focusonfocus

11-01-2009, 08:08 PM	#8 (permalink)
Zoomer69 Senior TEAM Member Join Date: Jun 2002 Location: Madison, WI Posts: 1,723	Re: what if i,,,and keep drive..?? I highly doubt the o2 sensor has gone bad again. First of all, a bad o2 sensor would have thrown a code, just like before. Bad wiring would have also caused it to throw a code for a bad o2 sensor. Secondly, the o2 sensor doesn't even begin to function until the engine is warm, and therefore the sensor itself is warm. The motor is working from its cold-start tune (which is a richer tune than normal) until the o2 sensor is hot enough to begin working. Also, the engine goes to that cold-start tune when the o2 sensor is unplugged as a fail-safe, so the engine doesn't grenade itself from detonation from running lean. You might want to try this again after unplugging the computer and letting it sit (to clear out the computer's memory). Try it once with the o2 plugged in, and if it misfires, try it again with it unplugged. You could also try it with a known good o2 sensor in its place, though I doubt that would change anything. My assumption is that something else has gone wrong - that some other sensor (MAF, coolant temperature sensor, etc) is giving faulty data to the computer until the o2 sensor light-off occurs. __________________ Flashing lights in your rearview mirror getting you down?? Stop being cop-bait! 8)

11-01-2009, 08:14 PM	#9 (permalink)
focusonfocus Senior TEAM Member Join Date: Jul 2004 Location: toronto, on Posts: 4,176	Re: what if i,,,and keep drive..?? i gotta unplug sct chip first to get engine code.. because this sct chip is keep clearing code.. disconnect ecu, not battery?? __________________ Advanced MECP certified mobile installer 2000 Kona Dirt. www.cardomain.com/id/focusonfocus

11-04-2009, 09:54 PM	#10 (permalink)
focusonfocus Senior TEAM Member Join Date: Jul 2004 Location: toronto, on Posts: 4,176	Re: what if i,,,and keep drive..?? oh ****..it was focussport sct chip i had it for 5 years.. 1 pin on sct chip looks bit weird..running hot or shorted or something.. but now put back o2 sensor back and ran for 2 days now and the problem is not there anymore.. car is not fun to drive anymore without chip but runs better at least.. __________________ Advanced MECP certified mobile installer 2000 Kona Dirt. www.cardomain.com/id/focusonfocus

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