Had some time to myself this afternoon as I wasn't at the workshop. I have been having a few issues with boost control ever since my latest map had the boost upped from 1.4bar to 1.7bar.... Boost has been dropping off randomly or wavering between 1.4 and 1.6bar rather than holding as it should... I initially put this down to the actuator and was going to try a bit more preload as this helped the last time I had a similar issue...
I have tried an MBC (manual boost controller) before but without much success... I couldn't be bothered to play with it previously but thought I would give it another go...
Using a Forge UNOS MBC I bypassed the N75 completely (leaving it electrically connected and blocked the pipe going to the TIP) and gave it a try.
It was one that Bill had used on the Polo build while mapping so should be set about right... however, when I tried it I was still getting varying boost so I fitted the stiffer spring that comes with the UNOS, wound it back to its softest setting and tried again... steady 1.4bar this time... wound it up 20 clicks... over 2bar!! eeep!!... wound it back 5 clicks and it settled nicely at 1.8 (ish) bar....
Car was pulling nicely and it held boost pretty much up to the redline...sweet!!!
Think I will fit that in properly now as its just lazing about the engine bay at this moment (I have cable tied it in now)
Max airflow I got from that run was 282g/s... this is lower than I have been getting in the past as my MAF is a little tired... I have previously been only getting in and around the 270 mark where I have logged over 290 before... I have previously tried a MAF Bill had on the shelf and my airflow was back up at 292g/s so a new MAF and pre-cat lambda are on the shopping list for the end of the month.
The 282g/s was encouraging though as the MBC appears to be working nicely and maintaining boost keeping the airflow up. This was when I decided to have a go at de-meshing the MAF...
De-meshing the MAF has been discussed before and that ASN pioneer of modding Welly has done his... I am little sceptical but thought 'what the actual hell!!!'
Here we have an S3 MAF... grille thingy at the front (airbox side)
..and TIP side...
TIP side grille was an easy job to remove..
The airbox side less so... this is where the 'mesh' is. The plastic grille is retained in the MAF housing so I ended up having to push from the inside of the MAF while unclipping the retainers to allow the grille and mesh to pop out... I damaged the mesh doing this, good job its not going back in
And there you have it, one de-meshed MAF...
Fitted it back on the car and did a couple more runs.... got an airflow of 291g/s!!! same setting on the MBC, just a de-meshed MAF...
Not a bad increase for a hours messing about... 270 to 290 g/s :icon_thumright:
There is some discussion on another thread about the validity of this increase and the MAF ability to now accurately measure the airflow now that it can no longer be stabilised by the mesh screen... I am on the fence with this, I am not convinced it would over read the air but under read if anything at all. I will be logging block 001 amongst others to keep an eye on real time ECU correction to fuelling and keeping an eye on long term fuel trims to see if fuel is being removed or added in any great quantities that would back up a misreading MAF.
Hoping to get the new MAF, lambda and finally my EGT probe sorted next weekend if I and of course Bill can find the time.
Car is driving great at the moment, feels stronger than it has done in a long while... I is a happy chappy
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