So, my R55s is having problems again.

First off, no codes what so ever.

Problems I have are sudden bad milage, irregular at iddle, irregular at constant speeds. Car is running verry rich. Almost drowning in petrol, smells like it to.

All hoses and tubes are checked, no leaks there. Airfilter is clean. Can anyone point me in a direction? Injectors? Diverter valve? O2 sensor maybe , or woud that throw a code?

 

How about bad gas.

 

Thanks for the reply, thought of that too, but ruled it out already. I always fill the car up with premium petrol, and have filled up twice since the problems started.

Car is drivable, but that rich can't be good on long term. And it's really annoying that no codes pop up and it's unclear what's causing it.

 

High pressure fuel pump? Do you have hard starting?

 

Do you have any pending CELs?

Might be worth checking your intake ports/valves for carbon buildup. Severe buildup effects performance and mileage.

Other than that, you really need a BMW scan tool to check all the recordable parameters to see if anything is setting off a red flag.

 

Starts just fine, no problems there. No pending CEL's also. Car is checked with a universal scan tool, Snap On Solus. Lambda readings are not normal also, but I figured that's due to running that rich.

Better get it tested at BMW dealership than.

Thanks!

 

Oh, and got the sparkplugs replaced about 4000 miles ago.

 

If your O2 sensors are giving bad information to the ECU it can make the car run lean or rich. Don't jump to conclusions though. You really need to check everything out with a BMW scanner

 

Thought I give you guys an update....It was a faulty O2 sensor. So problem solved, only the weird part is, even with the O2 sensor disconnected, it didn't result in any codes or CEL what so ever.