02 sensor/hesitation issue - Rev2 tubby (Poss one for LMT!)

[madmr2man]

Hi All,

I'm having some issues with my car hesitating and overfueling, and it must be to do with the o2 sensor wiring as that is the only thing I have touched since it worked last
I will attempt to give some condensed background info first......

* When I bought the car in 2008 it had a Tomei narrowband AFR gauge installed. It worked as well as a narrowband could, so I left it installed. I was a little scared of the mess of wiring behind the A-pillar and bodged into the stock o2 sensor
* I bought and installed a PLX Devices wideband AFR this year, it's brilliant and works really well
* I removed all the old AFR wiring at the A pillar, and cut a hell of a lot of junk out. The only bit left was the loom that came from (I believe) the bodged wires into the stock o2 sensor
* The last point did create some temporary parasitic drain issues, which I have since resolved
* The botched o2 sensor/narrowband AFR wiring right above the stock o2 sensor was suffering heat damage, having been wrapped in electrical tape, self amalgamating tape and anything else the previous botcher could find
* For some reason my car has a 4 wire sensor fitted, despite being a rev 2 which I believe should only have 2

So, with the o2 sensor cable sheath bubbling away nicely under heat, I ordered some heat resistant glass fibre tape, and last night removed the top 2 intercooler pipes and set to work stripping it all back.
It actually all came away ok, revealing wires that had been twisted together amongst other things.

So i traced the wiring, and the blue o2 sensor wire goes connects correctly to a wire that heads off into the loom that goes over the cam cover and to the ECU. The Tomei AFR system was spliced into this line, so I cut that out. One of the black wires was earthed to one of the nuts that holds the the firewall heat shield on, and the other one went off into the Tomei AFR loom. The white wire also went off into the Tomei AFR loom.

I reasoned that I didn't need the black heater wires as I have no means to power them or switch them off when closed loom is reached, so I clipped them and insulated them.

I was going to attach the white ground wire to the existing heat shield ground, but then I noticed some cable strands coming out of the stock loom next to the sensor cable. I tested this and found it had continuity to ground, so i used this for an o2 ground in the interest of neatness.

So given my running issues, this raises a few questions:

*How will the o2 sensor behave if it isn't grounded or incorrectly grounded?
*Where does a stock rev2 o2 sensor ground?

Just to be clear, I've not touched anything else, and the car drove well beforehand.
I also know the car is overfuelling because on boost the gauge goes off the scale rich.

Any ideas peeps?

Cheers

Mad

[madmr2man]

Not that anyone has posted, but ignore this thread.

It would appear that I am an idiot, as I failed to do up a boost hose properly

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[littlemisstubby]

Aaahh yeah that'll do it.

Glad it was an easy fix mate.

[madmr2man]

Aaahh yeah that'll do it.

Glad it was an easy fix mate.

Lol, I spent ages writing that n all! :-)

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