New air filter
Discussion
I have custom fitted a new rather large KN cone air filter to my classic wrx sti, same filter used by the gobstopper impreza. it replaced a very grubby smallish apexi cone filter, air filter is the only thing i have changed so the engine will be getting more air. the car has a few other engine mods and is running about 330 horsepower ecu is ESL mapped. if the engine needs it will this ecu adjust the air/fuel mixture accordingly ?
If you didn't receive the email i sent yesterday this is what i wrote....
The MAF may need to be rescaled. Even on a Factory ECU the MAF has to be rescaled when moving to a bigger air filter. That way you're telling the ECU it's reading the right amount of airflow so it fuels accordingly. There is no automatically corrected compensation for it, no ECU does that. It may start to run lean.
The only way to tell for sure is to plug in and see what it's doing alongside a wideband to check fuelling and set of det cans to listen out for knock.
Having now looked at the RCM website that cone filter and trumpet looks pretty big but equally having looked at the MAF sensor for your car i forgot it comes in it's own tube therefore unless you physically take the MAF sensor out of it's housing and into a bigger housing you should be fine. If you start it up and it runs rough as some do when moving everything upscale, then it's more than likely it will need rescaling.
The MAF may need to be rescaled. Even on a Factory ECU the MAF has to be rescaled when moving to a bigger air filter. That way you're telling the ECU it's reading the right amount of airflow so it fuels accordingly. There is no automatically corrected compensation for it, no ECU does that. It may start to run lean.
The only way to tell for sure is to plug in and see what it's doing alongside a wideband to check fuelling and set of det cans to listen out for knock.
Having now looked at the RCM website that cone filter and trumpet looks pretty big but equally having looked at the MAF sensor for your car i forgot it comes in it's own tube therefore unless you physically take the MAF sensor out of it's housing and into a bigger housing you should be fine. If you start it up and it runs rough as some do when moving everything upscale, then it's more than likely it will need rescaling.
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