Shane@DBPerformance
12-29-2003, 10:26 AM
MAS overrun is when it's sucking in more air than the MAS can accurately keep count of. It isn't a problem with a 2G MAS until your making 450whp or so. It is a problem much much earlier on a stock 1G MAS. You might have overrun issue at even less than 300whp on a 100% stock 1G MAS, I am not exactly sure when it starts happening. Most people have already at least removed the bottom honeycomb by that time. With just the bottom honeycomb removed I have had it happen in the low 300s. Overrun problems usually seem to start happening around the 2000hz area on the AFC with the 1G MAS.
With a very hacked 1G MAS though you can make well into the 400s or more and keep the hz down low enough to keep overrun from happening. You just don't want to go overboard with the hacking though. Hacking the MAS more than it needs to be can cause some knock/timing tuning problems. You usually only want to hack it to the max if your running a big turbo and injectors that are just big enough for the setup. I had one 14B car with too big of injectors that just removing the bottom honeycomb was enough to cause problems. With a medium amount of airflow signal being removed by the AFC to get the fueling inline and the missing lower honeycomb causing it to measure even less of the actual airflow, the ECU wanted to run the car in an incorrect timing map with way to much timing which ended up making the car knock.
With a very hacked 1G MAS though you can make well into the 400s or more and keep the hz down low enough to keep overrun from happening. You just don't want to go overboard with the hacking though. Hacking the MAS more than it needs to be can cause some knock/timing tuning problems. You usually only want to hack it to the max if your running a big turbo and injectors that are just big enough for the setup. I had one 14B car with too big of injectors that just removing the bottom honeycomb was enough to cause problems. With a medium amount of airflow signal being removed by the AFC to get the fueling inline and the missing lower honeycomb causing it to measure even less of the actual airflow, the ECU wanted to run the car in an incorrect timing map with way to much timing which ended up making the car knock.