Help please. I'm giving it one last go!

[Laird Scooby]

Originally Posted by Mkengineering

So is everyone saying I change the o2 sensors?

As there are 2 sensors on this car. Someone told me that the sensor at the front is basically a moron while the rear sensor does all of the mixture.

Oh dear. Other way round. The pre-cat sensor is the one that does the work, the post-cat sensor monitors the cat performance and is also a double-check on the pre-cat sensor.

If the post-cat sensor registers the same O2 content as the pre-cat sensor, it means the cat isn't dealing with the CO and other gases. If it reads appreciably higher CO than the pre-cat sensor, the pre-cat sensor output has failed.

In other words, the one to look at changing first would be the pre-cat sensor. If you can, reset all faults codes afterwards to give the ECU a "clean sheet" to work from.

[Mkengineering]

Originally Posted by Laird Scooby

Oh dear. Other way round. The pre-cat sensor is the one that does the work, the post-cat sensor monitors the cat performance and is also a double-check on the pre-cat sensor.

If the post-cat sensor registers the same O2 content as the pre-cat sensor, it means the cat isn't dealing with the CO and other gases. If it reads appreciably higher CO than the pre-cat sensor, the pre-cat sensor output has failed.

In other words, the one to look at changing first would be the pre-cat sensor. If you can, reset all faults codes afterwards to give the ECU a "clean sheet" to work from.

Okay thank you for clearing that up for me.

Ill order a o2 sensor and do a change over. Unfortunately i dont have anything that will read the Clear the ecu.

Ive wasted even more money of trying to find a decent OBD2 reader to find that there actually isnt any around.

[PNuT]

If you have two O2 sensors it would be worth checking what has been done with the ecu as well & what version of motronic you have!!! I am not sure if two sensors were fitted here as standard on 4.3?


It does sound like the O2 sensor to me! I suspect it runs best at WOT?

[Paul240480]

Wouldn’t a duff O2 throw a code?
Another thought, engine temp sensor.
Just thought worthy of a mench,

[Mkengineering]

Update .

Installed new Bosch o2 sensor and theres no change at all.

[Mkengineering]

Originally Posted by Paul240480

Wouldn’t a duff O2 throw a code?
Another thought, engine temp sensor.
Just thought worthy of a mench,

Apparently not. Well not on these cars

[Laird Scooby]

Did you reset the ECU after fitting the new Lambda sensor? If not, it probably hasn't registered the fact the Lambda is now working again.

[PNuT]

Originally Posted by Paul240480

Wouldn’t a duff O2 throw a code?
Another thought, engine temp sensor.
Just thought worthy of a mench,

Engine temp sensor will make it run rich as it will be in closed loop but it shouldn't be 5-10 mpg.

Something is making the injectors run full duty cycle by the sounds of it!

so the car thinks it is running lean!

[PNuT]

Originally Posted by Mkengineering

Apparently not. Well not on these cars

Has the car ever worked properly while you have had it?

Does the O2 sensor wiring look standard fitment?

Is it possible the two sensors have been switched to the wrong position?

so the proper O2 sensor is now post cat and trying to richen things up!

[Mkengineering]

Originally Posted by PNuT

Has the car ever worked properly while you have had it?

Does the O2 sensor wiring look standard fitment?

Is it possible the two sensors have been switched to the wrong position?

so the proper O2 sensor is now post cat and trying to richen things up!

The car did run fine until I installed the shemtek map and ever installing a snaab intake system.

But ive tried reverting back my normal setup bar the injectors and standard intake and found that the car wouldn't even want to run?

So I'm completely lost on this.