Sean cause that's what other Vauxhall tuners do who don't know how to do 90mm MAF despite it being a simple process and just takes a bit of dyno time..

New conclusions: car runs like crap at idle no matter if MAF is connected/disconnected, after it heats up everything is fine, I assume this is because of shitty 630cc deka's installed. Even raising idle at 1300rpm to avoid low revs running does not seem to cure this behaviour.

With new MAF sensor installed yesterday the engine will die after a full boost run because of the reason you explained, the BOV will release air and mixture will go rich, if I rev the engine while the revs go down after a dyno run, the engine does not stop anymore. So problem solved - seems old sensor was damaged.

Now, let's get back to my main issue - last night tests maxed out the 80mm MAF from first run so it is obvious that this MAF cannot cope with 1.6bar of boost.

I have an EVOMS 90mm housing. I obviously can take 80mm sensor and move it inside new housing, but as I said, I cannot make the new linearisation map by simply multiplying old linearisation map with the ratio between new diam/old diam squares. It does not work, at least for me it doesn't.

I also cannot use an RS4 linearisation as I assume sensors are not the same. My sensor is F00C2G2063, this is bosch code.

I have dyno, if someone is kind enough to point me in the right direction to calibrate this new MAF housing, I appreciate and will follow the advice.

Thanks.

I have a tough time believing you are maxing the 90mm MAF at your HP levels.... are you sure you aren't running into another limit? Have you logged MAF voltage?

an 85mm MAF should be good up to 700ish HP.

Might be a long shot but deka 630s don't really have good QC in regards to the spray pattern. On mine, the spray pattern was not consistent between any of the injectors and was not even close to stock. I marked the injectors to be able to index them upon reinstall. After I installed them and verified that they were aimed correctly, my cold starts were much better and I could drive immediately after starting the car. Just a thought...


You will not be able to scale in a new MAF 100% unless your fueling is dead on.

@nyet: I am reffering to LEH 72mm inner diameter MAF that is maxed out, probably the 85mm one should do the job, as long as it is well calibrated.

I am using upgraded intake manifold but stock throttle body. Boost went 0.1bar higher on MAFLESS than with MAF installed, AFR went a little bit leaner, but still in an acceptable range- 11.2-11.5. There was a problem on this MAFLESS run, a certain drop in torque at boost peak rpm range, boost went at aprox 1.6bar for a little time, I suppose ecu made a little correction as I have seen on other similar cars that ME1.5.5 does not like more than 1.55bar boost and makes a little correction if original pierburg valve is governing the turbo pressure and this is not done via separate boost controller. My experience on this ECU is limited, still not found what could possibly cause this correction once the boost exceeds 1.55bar. As long as boost is under this value, which is also the stock MAP sensor max value, everything is fine. I thought the key to this problem is to install a 2bar boost MAP, which I did (including calibration via gradient and offset), but seems it does not solve the issue. I still have a lot to learn about this ecu, please do not laugh at my mistakes.

The dyno run plot I am talking about is called softv2, and is blue. The other plots are several attempts at lower boost and lower injection advance, but the car heated and the other plots are not so concludent because you can obviously see that performance is poor in comparison with first run.

Why your torque peak is that late i.e after 4700 ? On what gear you made dyno runs and with or without eddy brake load if you have such ?

Btw about 85mm MAF scaling.......if you already have real 72mm MAF curve, try to up it whole by 39% and then put MAF offset 280kg/h instead of 200 like in stock file. You need to have around 3-3.5g/sec airflow on idle, if not try to +/- offset value a little bit

The run was made in inertial mode, due to long gear ratio I did not brake the dyno, although I have this option.