I bought a new blow off valve, Turbosmart BOV Race Port GenV(50mm). My car is stock (power) with stock turbo. Somebody said me that this BOV is not good for my turbo. He says that it won't make some noise on standard Turbo. It doesn't make sense to use it when I have MAF sensor. What I have to do? I paid almost 300€ for that BOV.

Stop talking to that person and just fit it

The Bosch 2.10.4 ECU performs the majority of its fueling management based on metered air flow data from the MAF. The standard re-circ valve feeds excess air back into the intake system after the MAF - this excess air has been accounted for by the ECU via the MAF and fueling adjustments have been made accordingly.

If you fit an atmo blow off valve you waste this air out of the intake system after the ECU has made a fueling adjustment to cater for its presence. This can result in an incorrect fuel mixture.

If you examine the fuel trims using something like Multi ECU Scan you will see that they go out of spec and likewise the lambda integrator can become erratic. It not a disaster, it simply means that the engine is not working at its most efficient. The choice is yours.

thx,mate for answer! He told me the same thing you did. Do i need a blow off valve at all? Which one should I buy then for standard turbo?

Of course you need one, because the turbo boost will surge when you close the throttle after accelerating. That air needs to be exhausted somewhere outside the intake pipe leading to the throttle body.

I have fitted a VAG recirc valve on mine (something for Audi/VW 1.8t are really cheap and accessible), and I think it works okay.

I found one on the eBay. Lot of people had suggest me this one called Forge FMDV008. I think that this one is better option for stock car. I will save my Turbosmart and use it when I upgrade my engine.

hi, sorry if I intrude, the question also interests me, having a valve that can discharge the air, both outside and inside the intake pipe. the question is: with gtech2 + straight intake pipe + external filter + front intercooler + manual boost valve. but with original turbo, can the air be released into the atmosphere? or do you have to map live for this?

There is no escaping the fact that Bosch Motronic 2.10.4 uses the MAF the way it does.

Above 3k rpm the lambda controls the fuelling not the MAF, fitting that BOV won't make any difference as it's still vacuum controlled on overrun via the plenum, we fit all kinds of different makes without any issues, you'll just need to know what spring rating is correct.

Lambda controls the fueling below 3k rpm too and drops out based on engine speed and load, its range can be altered via a map. However that is besides the point Likewise the spring rate on an atmo BOV, that relates to boost levels and is nothing to do with the ECU measuring airflow !!???

The MAF is used by the ECU across the board and many calculations are made based on its signal. When the ECU ignores lambda under heavy boost, MAF values are still taken into account. See Big Maf conversion for very highly tunes engines.

As I said in my original response, its not a disaster using an atmo BOV, the engine will just not be running at its most efficient - its really easy to see on the fuel trims.

Yes ok..................

hi, Clanger I'd like to understand what you mean by "its really easy to see on the fuel trims". can you explain it to me better? It's very interesting. what to do with badly burning gasoline and carbon buildup on the valves? thank you