Disconnecting o2 sensor for full open loop mode - UPDATED

boostjunkie · Post by **boostjunkie** » Fri Dec 12, 2003 6:03 pm

Has anyone done this? How does the car drive?

I might need to do this to get by while I'm busy trying to figure out this a/f learning control code. In the meantime, I need to have the engine run as rich as possible.

So what are the sideeffects? Stalling, crazy idle, etc.

evolutionmovement · Post by **evolutionmovement** » Fri Dec 12, 2003 6:45 pm

Isn't the car in open loop before the O2 warms up? I imagine it would drive the same as when it's cold.

Steve

entirelyturbo · Post by **entirelyturbo** » Fri Dec 12, 2003 7:12 pm

I recall Josh saying he did it once, I believe he said it did him no good except light up a CEL obviously...

vrg3 · Post by **vrg3** » Fri Dec 12, 2003 8:22 pm

I've done it before. In fact, I once went on a road trip from Ithaca to DC for several days without the oxygen sensor connected. I didn't notice much difference in the way my car ran; there was perhaps a little less power but not too much.

I also have read about people using EJ22s (turbo and non-turbo both) in aircraft without oxygen sensors. They're just going for simplicity so they don't install a sensor at all.

My car actually passed a Virginia State emissions inspection and test in that condition. :)

boostjunkie · Post by **boostjunkie** » Fri Dec 12, 2003 8:31 pm

Now do you think I should just snip the o2 signal wire at the ecu so I can read the values?

I'm a bit iffy about doing this but I'd rather have the engine run safely (rich is better than the readings I'm getting from my gauge).

THAWA · Post by **THAWA** » Fri Dec 12, 2003 8:44 pm

why not just disconnect the connector at the plug? It's hard as hell to do though.

legacy92ej22t · Post by **legacy92ej22t** » Fri Dec 12, 2003 9:00 pm

I was running with a bad O2 sensor for a while. I wasn't getting CELs but had one stored in the ecu. My car ran extremely rich, you could really smell it. The car would feel bogged down but only at WOT and it was a little inconsistant. Besides that it really didn't make much of a difference. If you're running high boost maybe you'll actually benefit from it.

I would just disconnect it and tape both connectors to keep them clean. It really isn't too hard just use a small flat head screw driver to pop it.

boostjunkie · Post by **boostjunkie** » Fri Dec 12, 2003 9:37 pm

I actually disconnected the sensor inside the car, just to keep the elements from getting to the break. Decided to keep my a/f gauge wired in (will hookup a voltmeter later to test that) just so I could read the values.

Strange.

It will SOMETIMES read rich. When idling it will read all crazy like before. Once I hit boost it's a DOG. Like pulled timing or something.

No CE light, either. For ANYTHING.

ARGH!!

boostjunkie · Post by **boostjunkie** » Fri Dec 12, 2003 10:25 pm

Gauge is working fine.

Hooked up a volt-meter instead of the gauge. It was showing similar readings. Just in case, I decided to hook them both up. Same readings. However, can an o2 sensor show a NEGATIVE voltage? I'm getting -.0something mV at times.

THAWA · Post by **THAWA** » Fri Dec 12, 2003 10:33 pm

might just be your voltmeter, like a flux in the line or something

vrg3 · Post by **vrg3** » Fri Dec 12, 2003 11:04 pm

It's really weird that you're still getting weird readings from the oxygen sensor. And negative voltages don't make any sense... Maybe probably got some bad grounds. The weird thing is that a good ECU ground and a high-impedance oxygen sensor ground would normally give you falsely high readings. So maybe your ECU grounds aren't so good? Bad grounding can cause
poor running in general.

Maybe you should try the grounding mod...

boostjunkie · Post by **boostjunkie** » Fri Dec 12, 2003 11:16 pm

I'll try anything at this point.

Post by **Legacy777** » Sat Dec 13, 2003 3:44 am

don't really do much of anything except make car run not so good.....

boostjunkie · Post by **boostjunkie** » Sun Dec 14, 2003 2:01 am

Okay. after finding out that the car was doggedly slow with the o2 sensor disconnected I decided to hook it back up yesterday afternoon. a/f was off the mark as usual.

However, this morning I get into the car to take a drive and everything's fine. Tried boosting and it boosted fine too.

I'm so confused.

IggDawg · Post by **IggDawg** » Mon Dec 15, 2003 5:48 am

See my comment in your other thread in the electrical forum. I think your problem may be your TPS. It's a quick check, and at least you can scratch it off your list of likely suspects if it's not broken.

boostjunkie · Post by **boostjunkie** » Mon Dec 15, 2003 3:03 pm

Just swapped out a new TPS and checked all of the signals. Even the idle switch is set to specs. *shrug*

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Disconnecting o2 sensor for full open loop mode - UPDATED

Disconnecting o2 sensor for full open loop mode - UPDATED