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Originally Posted by jaykay
Thanks, that sounds like quite a set up. I will search your posts for some images! I will have to read up on Bosh fuel injection but those AFRs sound like stock which is quite amazing given all your changes.
It is interesting you are working on a spoiler intake. Many many years ago when the Boxster first appeared on the road and I knew nothing about them, I thought the spoiler element coming up was to facilitate some sort of cooling airflow.
what actual mass airflow sensor did you use with your set up.....would imagine that a 996 one would create the least issues.
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I used the original 986 OEM MAF sensor from my boxster. The two are the same part # between the 986 and 996.
There is something worth noting here - these modifications (along with the 2.5" exhaust I did) were phase 1 of a much larger project, which is a low pressure high flow twin turbo setup.
After much research, I came to realize that our ECUs were incredibly advanced for their time and are still more capable than nearly every aftermarket ecu setup (save for a motec system, but that's a different discussion). The setup I designed would produce 300-325hp, which in turn pushes the airflow parameters and fuel requirements outside of the stock maps for a 986 though so I needed a workaround (stock maps have +/-20% built in on either side on nominal to account for varying conditions). However, this is perfectly in line with the 996 performance specs. So, the simplest thing to do for me was to simply convert the ecu maps to those of a 996. Even without the FI I had a feeling that my power production would be high enough to stay within the 996 maps by making the intake and exhaust modifications, which it is.
The beauty of our ECUs is that it has no idea what displacent motor you have. It uses 2 primary inputs (airflow in and which side of lambda your exhaust is on) to dictate two outputs (injector pulse width and ignition timing). We could talk for hours about this...point being you just have to make sure that the inputs are accurate for the ecu to do its job.
To that point, you have to match the tune to the intake. The 996 maps are based on MAF sensor readings through a larger diameter housing. So, If you keep the MAF housing diameter stock (regardless of where the sensor is actually located) you don't need the 996 maps. This would even be true for a low pressure single turbo setup. If you upsize the MAF housing though, either with a cayman airbox or a custom setup, a tune will be required (either a 996 tune or, if your car is 03-04 the anniversary 986 Spyder tune will work as well).
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