330ci running rich

[mini1380cc]

I recently bought a 330ci auto which at best gets 16mpg and typically 8mpg. As a starting point i changed the air filter and oil/oil filter. I also replaced the thermostat and water pump as a precaution.

I pulled the codes which show a lambda error for each bank both of which suggest the mixture is too rich. Live data suggest the both sensors in each bank work as intended. I also believe the MAF to work fine. The car runs smooth and pulls as it should.

I found a tear in the inlet boot which i plan on replacing asap but i thought vacuum leaks only cause a car to run lean not rich.


Anybody got advice on rich running BMW straight 6's?


Cheers

[rumple]

that is amazingly bad consumption for a 330, does it warm up cos a knackered thermostat will make it drink it as well, id post this on bimmerforums or something cos that 330 is ill.

[mini1380cc]

Yeah i just done the thermomstat as it wasn't warming up properly. It now warms up as it should. Today I managed to eek 19mpg out of it and that taken some effort. Picking up a new intake boot today so i should have that eliminated by tonight.

I'm just stumped as to why a vacuum leak could cause it to run rich. Everything i know about vacuum leaks always ends with the engine running lean.

[Salom]

I have just fixed the same problem with my 330Ci, you need to get the codes read, luckily I have the kit to do this, turned out to be a Lambda Sensor, the car is fine now..

[mini1380cc]

I had the codes read which said that the lambda sensors were reading rich. If it were just the one bank showing this I would have no issues with replacing the lambda sensor. But both sensors running independently on separate manifolds giving the same errors. What is the chances?

I might order one sensor and if the error clears on on bank I'll know the same will work for the other bank.

How did you know which sensor to order? By this i mean ECP list 5 different bosch sensors for the car and it doesnt state which is pre cat and post cat, bank 1 or bank 2.

[robbo32]

Hi,

not sure that with a tear in the inlet pipework it will run lean.
Depending on where its torn the ecu might be trying to inject more fuel to match the increased air flow going in.

[Salom]

mini1380cc said:

I had the codes read which said that the lambda sensors were reading rich. If it were just the one bank showing this I would have no issues with replacing the lambda sensor. But both sensors running independently on separate manifolds giving the same errors. What is the chances?

I might order one sensor and if the error clears on on bank I'll know the same will work for the other bank.

How did you know which sensor to order? By this i mean ECP list 5 different bosch sensors for the car and it doesnt state which is pre cat and post cat, bank 1 or bank 2.

My diagnostic hook up told me exactly which one was causing the problem, in my case it was 'Sensor 1 Bank 1', I changed it, cleared the fault and as I say the car is fine now.

Sensor 1 bank 1 is pre-cat
Sensor 2 Bank 1 is post-cat
Sensor 1 Bank 2 is pre-cat
Sensor 2 bank 2 is post-cat

I got mine from here; http://www.lambdapower.co.uk/

Just enter your car details..

Hope this helps..

P.S.

The senors are generally the same, it's only the lead length that varies, so the shorter lead is Sensor 1, the longer lead is Sensor 2. Also; buy a 'direct replacement', don't go for the 'universal' option.

Edited by Salom on Monday 30th January 12:42

Edited by Salom on Monday 30th January 12:47

[mini1380cc]

Well i've just replaced the upper and lower intake boots and had it out a short drive. Computer now showing 23/24mpg and no new error codes.


A longer drive will confirm but i think it might be fixed.

Whilst i was in BMW getting the boots i asked about 02 sensor prices for curiousity. £173 ex vat each!

[mini1380cc]

RESULT.

I can confirm that replacing my tor intake boots has solved my lambda sensor error problem. Thanks all that helped.


Mini