[335i E92]

Hi

Having problems since having new turbos fitted, basically have rough idle, bad mpg, part throttle surging and general rough running.

Checked all injectors, boost & vac leak, plugs and all are 100%.

These symptoms kicked in straight after turbos were fitted so the only part on the car that was messed with on the day were the 02 sensors (which are now on 90k)

Thing is I had disregarded them as the above issues are present when the engine is cold or warm. The only way I could put it down to 02 sensors was if our 02 sensors are self heating which would mean it goes into closed loop within seconds hence affecting both hot & cold engine situations.

So, anyone know if our sensors have their own heating elements? This would really help with my diagnosis if anyone could chime in?

Thanks!!

[Dan-danGT]

Most o2 sensors I know of are heated. I would say yours is the same!

[335i E92]

Great, so you rekon a faulty 02 sensor on our cars can affect the engine performance when cold? If so I rekon that's my problem!!

[Dan-danGT]

Anything is possible, not ovally conversant with the petrol models. But I believe one sensor is for mixture and one for the cats? Not so sure though, do you have any fault codes?

[335i E92]

Nope, but I know its still possible that their toast without throwing codes.

Heated 02 sensors can get to operational temp within 10 seconds if thier heated so if they are on the 335i then I'm pretty sure this is my issue.

[m1bjr]

You could break into them and actually measure the voltage on both banks.
Or best to do it via an OBD2 scanner.
It would be immediately apparent.

Often errors don't log though unless they are well outside operation possibilities (knackered).
It sounds likely given the history.
OR they haven't adjusted the wastegates properly and reset the adaptations

[335i E92]

They've double checked the wategates and I've had all adaptations reset, even had it flashed back to oem software so hoping its the sensors!!

As I said I had eliminated them as a possible cause but given they might be heated I'm gonna replace n hope it solves my issues.

[Nigelo]

One of the common issues involving the O2 sensors is when both have been unplugged and then connected up again with the harnesses swapped over by accident - and sounds like the symptoms you're having.

No lights on the dash though? One of my primary O2 sensors has died last week, and it threw up a eml pretty quick, as well as a code or 2. The car runs fine while warming up, but once near to full operating temp I get the same issues as you. But if I reset the codes while the car is warmed up, although the eml light still comes on, the car drives nearly 100% again.

The N54 runs quite often in closed loop mode I think.

Hope something there helps!

[335i E92]

No codes as I said but I think it's faulty but not completely fooked.

Had all the work done at Darren Woods n they said they definitely put them back in the correct order, tbh the O2 sensors have been off my car so many times over the last year or so when the wategates needed adjusting n stuff so they're probably just worn / damaged by now.

[335i E92]

Anyone know the best place to purchase both the 02 precat sensors?

I've looked at the below on the Bosch website but tbh wouldn't know which ones to buy, lots of different part no:

http://www.bosch-automotive-catalog.com/public/catalog/products?p_p_id=BoschWSRP&p_p_lifecycle=0&p_p_stat e=normal&p_p_mode=view&p_p_col_id=column-1&p_p_col_count=1&_BoschWSRP_wsrp-navigationalState=%2FWFS%2FAAGLOBAL-AA-Catalog-Site%2Fen_GB%2F-%2FEUR%2FViewVehicle-ViewEquipment%3Bpgid%3DD41D8CD98F00B204E9800998ECF 8vzwD2rJi%3Bsid%3DGmodgVUaejp0ggSVSDSRe1qRUBjVTB9o 0qc%3D%3FVehicleMake%3DBMW%26VehicleNumber%3D814%2 6EquipmentBereich%3D10&_BoschWSRP_proxyportlet-remoteInvocation=true

[idnan]

Part numbers are 17098 and 17099 from what I remember. The Bosch ones are exactly the same as the BMW ones but don't have the 'BMW' stamp on them. They are over £100 each on eBay.

How did they check the injectors? I had bad surging at under load and the odd code show up but mine were in a bad shape. I think you were there when my car was smoking on the standard turbos. My theory is that I popped a turbo oil seal which contaminated one of the sensors.

[335i E92]

Originally Posted by idnan

Part numbers are 17098 and 17099 from what I remember. The Bosch ones are exactly the same as the BMW ones but don't have the 'BMW' stamp on them. They are over 100 each on eBay.

How did they check the injectors? I had bad surging at under load and the odd code show up but mine were in a bad shape. I think you were there when my car was smoking on the standard turbos. My theory is that I popped a turbo oil seal which contaminated one of the sensors.

I've already had all 6 injectors replaced during the last 12 months so when I say checked they were removed to check for carbon build up and the plugs were in class a cond so didn't really point to injectors.

Thanks for the part no's buddy!!

[idnan]

Originally Posted by 335i E92

I've already had all 6 injectors replaced during the last 12 months so when I say checked they were removed to check for carbon build up and the plugs were in class a cond so didn't really point to injectors.

Thanks for the part no's buddy!!

I see, seems unlikely that the injectors are the cause. Out of interest, what remap have you got how have they turned the EML off due to the downpipes?

[335i E92]

I've got catted AR dp's and an evolve stage 2 tune.

Saying that, I've been running the latest standard oem map for the last week or so whilst trying to diagnose this issue n no codes or warnings with the catted AR pipes.