Grrrrrrr. Lambda Sensors

[deathrider311271]

another thing i have been thinking about as well, have you phsically checked your cat? given it a good old bang, its also possible its breaking down thus causing duff readings.

[JamesV70R]

Hmmm .. Would hope it isn't the cat - thats also not something I can borrow off someone lol!

Will see if I can get it to local garage or to "will work for beer" mechanic/monkey friend, and see if he can take a look at the cat for me ... The rear 02 sensor is fluctuating as if the cat was fine though - or appears to be, its not fluctuating but around the .600 mark .. possibly a little high coming to think of it .. ?

[deathrider311271]

TBH i dont have a clue what the reading should be as my code reader doesnt do live logging on the back sensor. if it is the cat do what im going to do, fit a 100cel race cat

[JamesV70R]

lol, my car isnt worthy of a race cat - its a cat d with some dodgy bodywork and some squeeks/rattles.

The C70 when I get it however ...

[Chris_Rogers]

Originally Posted by Villan

Oh - sorry - Yes, Lambda was Genuine Bosch (I mentioned in an earlier post) and the MAF was an ebay special - (Didn't have £160 to throw on the car if it made no difference .. and it made no difference ... light was back on within the day)

The problem is neither the Lambda or the MAF IMHO. The Lambda has been changed 3 times now, the last 2 times they lasted <6 months before throwing codes, this time it lasted a few days. Unless Bosch have been making faulty sensors for the last 18 months ...

I'd suggest you reinstall the original MAF and disconnect the rear O2 sensor as I suggested some time ago.

[JamesV70R]

Chris, I have attempted to.

For the life of me I cannot fathom quite HOW the plug unplugs. It clearly doesnt pull straight out, and theress not exactly masses of room to get a grip of the plugs either.

[Chris_Rogers]

Usually there is a 'u' shaped clip that you have to slide to the unlocked position. Once the clip is in the unlocked postion the connector will pull apart.

[dpbayly]

Hi Villan

Sorry to hear your still struggling but i have to say deathrider is right copy MAF's are like a lottery as to weather they will work i only ever use bosch/genuine on customers cars, about 18 months ago i didn't heed my own advise on by wifes car and brought a cheap MAF from eurocarparts and got my fingers burnt, lesson learned.

What sort of smoke is it?

White=steam (bad news)

Blue=Oil (bad news)

Black=over fueling (I'm guessing it's this)

I dont know how far you are away from me but if you can get up to me one evening or at the weekend i will take a look for you i cant promise to cure but a fresh pair of eyes is sometimes all it takes.

Also its worth contacting gdphilips and see about maybe getting a genuine used MAF that can be confirmed as working if money is tight.

[JamesV70R]

Chris - managed to unplug the rear 02 sensor, no difference to the way the car ran - or not that I could tell. It did throw a code though -

P0036 H02S Heater Control Circuit Bank 1 Sensor 2

Then after about 2 mins another code came up ..

P1133 H02S Insufficient Switching (Bank 1 sensor 1)

When the 2nd code came on the engine ran slightly smoother.

DP - Black sooty smoke.

[Chris_Rogers]

It would seem to confirm the rear sensor is working within the parameters expected by the ECU diagnostic routines.

From what you've said (smoke) I assume this is black and is a symptom of over fueling.

From your experiments with the MAF sensor, I'd suggest the MAF sensor output is too high and causing the ECU to overfuel. You should be able to confirm this using OBD air intake volume live data.

Are you able to read short and long term fuel trim figures and air intake volume at idle and load?

I can't remember if you said your car has ME7 (electronic throttle) or Motronic 4.4 (cable throttle).

Either way I'd suggest replacing the MAF sensor with a genuine OEM part.

If you suspect overfueling at idle but weak mixture under load it would also be worth checking the fuel pressure.