Aftermarket cone air filter fitted - no MAS, problems

[stevedajones]

Hi. I have a Z4 E85 3.0 Auto which I bought a few months ago. A previous owner has removed the airbox and replaced with a cone air filter. There is no MAS fitted, just a loose wire. Aside from running rough at cold idle for a minute or two and being thirsty it seems 'ok'

This week I had the car go in for oil filter housing gasket. They repaired, steam cleaned the engine and gave the car back. At first it ran rough and they said probably water had got in somewhere. I removed the cone filter, washed and dried and the car seems to run as it did now before the gasket repair.

But I now have 3 x engine management faults:

P0102: Mass or volume air flow A circuit low
P0110: Intake air temperature sensor 1 circuit high
P0101: Mass or air volume a circuit range / performance

I keep cancelling but they come straight back.

Aside from the silly set up and missing MAS I am wondering why these faults never happened before the car went into the repair shop? I've done a couple 1000 miles since buying with no problems? My assumption is to buy the airbox and MAS from ebay and take back to factory set up? Could the car have been remapped with MAS delete perhaps? Would it run the way it does without that change?

Any help very much appreciated! Thanks.

Steve

 

[Stevo7682]

If your MAS is missing your engine cannot be running correctly or producing its peak power.
The Ecu will have reverted back to a map for the mas to keep engine going reasonably well but if the ecu doesn't know the volume of air entering the engine it can't possibly work the fueling properly.
This means it's probably running rich which will not be doing your very expensive bmw cats any favours.
Can't say why you didn't previously have the codes ( you should have as the part is missing).

Unfortunately a lot of the time unless it's an expensive set up with proper heat shielding and a fresh air intake then cone filters tend to be a placebo effect of sounds good on acceleration but actually it causes the engine to produce less power so sounds great but doesn't go as well.
Stephen.

 

[Andyboy]

Refit the MAF and airbox. Only ever use a Bosch, Siemens or Febi (rebranded Siemens) MAF and avoid Ebay crap as well as Bremi - none of them work properly. A secondhand genuine MAF should be ok.