Hi Folks,

I got this lovely '96. A friend called and said it had died 5 floors down in an underground car park 2 year's ago, and had to go as the condo was sold.
I went to see, and it would not start, flat tire etc.
I pulled it to ground level with a chain behind my mini van, loaded onto a flat bed and got it home.
The no-start was a crank sensor, and the car cleaned up nicely. New brakes and tires needed.
Then there was a noise like golf ***** rolling around the exhaust. The contents of the converters had broken up, and were rolling around.
I removed the cats and knocked out the remaining bits.
I cut the wires off the 02 sensors, thinking it would be easier to remove, and the 02 sensors would be of no use anyway now that the cat was gutted.
One tech I spoke to said the MIL light may come on, but it didn't.
Another tech said that the fuel economy may suffer without the 02 sensors. I'm guessing the ECU goes to a base MAP without the sensors.
With gas prices very high at the moment, can anyone speculate on this? The car runs perfectly but the dash read-out doesn't work. It's winter so I can drive it long enough to record fuel usage.

Thanks,

Rob

 

A bit surprising. But, then again, maybe not. The OBDII on these cars wasn't the greatest

I would agree. What I'm not sure about is the difference between base fueling and optimal fueling. Minor? Or Significant?

When you cut the wires did you happen to tag them to show which wires go to which sensor location? This would be helpful info you want to hook the sensors up again.

Cheers
DD

 

The car uses oxygen sensors to adjust fuel into the engine….whether there is a catalytic converter or not, doesn’t matter….at least for two of those sensors. (Not sure if Canada had the two or four sensor setup)

Without those sensors, your engine will stay in closed loop and will fuel according to a ‘set in stone’ fuel map.

 

Thank you DD and Vee.

Doug, I didn't mark the wires before cutting. I do have a wiring diagram if I replace everything. I guess I acted without thinking it all through. I'm afraid that's often the case with me.

I may have to put in a good cat with good 02's. But the car runs great, no rich-smoke etc.

I wish I knew if the fueling has increased a significant amount or not.

If I find an answer, I'll post.

Thanks,
Rob

 

Maybe an OBD2 reader could provide fuel consumption, and you could compare to another member's X300 (try several conditions, ie idle, cold or hot, etc)? Keep an eye on ambient temps for apples to apples.

 

It will overfuel. It has to. It’s not receiving any feedback from the engine. It isn’t taking into account any variable like temperature.

Google running a car in open loop, and you’ll understand what is going on.

 

Thats a nice looking car

I have had oxy sensor problems in X300 cars.
In Australian delivered X300 cars we have the two sensor system.
With unserviceable oxy sensors the biggest problem is a tendency to stall particularly after a highway run and and then entering suburbia.
Invariably pulling up at lights and then stalling or worse still stalling just after take off from the lights.
The car would re-start easily but it was a "dicey" situation of nearly being rear ended by following cars.
Replacing the sensors always got rid of the stalling problem
I don't know anything about the North American 4 sensor system but suspect no oxy sensors would produce similar results
Bill Mac
MK1
MK2
XJ6S3
X300 (X2)
15 previous Jags MK5 to X308

 

you can run the car with a LOT of sensors unplugged. even with the failsafe fuel map (no MAF connected) it doesn't run that bad, i think it was reading 25 highway.

 

The O2 sensors on my XJR died a couple of years ago, and I only noticed it through the increased fuel consumption, which I would estimate at around 5mpg, imperial. She certainly ran well, without issue or smoke, but she runs just as well with functioning O2 sensors! I would likely have failed my MoT test on emissions though.