SMT-5 and SMT-6
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Joined: Apr 2002
Posts: 61
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QUOTE
Red:
Actually he probably doesn't, that "trick" is generally called the Map Hack and is used for several different devices including the S-AFC and HKS VPC.
Your TPS sensor, MAF sensor and MAP sensor all works on a 0-5 volt DC return line. As such, you can "interchange" them sometimes depending on what you need.
By placing a MAP sensor on the SMT5/6 instead of the TPS, you have changed it's mapping abilities to a pressure-based system instead of a throttle-based one. This gives you the very basic ability to program fuel against manifold pressure, but it isn't always as glorious as you think.
The problem is that TPS mapping on the SMT5/6 is likely meant only for a placeholder, just like it is on the S-AFC. You essentially have "two maps" - one for low throttle and one for high throttle. If you rewire the device so it receives MAP signal instead of TPS, then you now have two fuel maps - one for "low boost" (ie vacuum) and one for "high boost" (ie manifold pressure above a certain threshold you set)
While you may think that this is a great idea, it instead gets a little wierd because you need to map against a LOT of manifold pressures, not just a low/high setting. It doesn't work as well as you think...
Getting those two signals to play nice together may work a little better on the SMT because of the flexibility of the SMT's analog defelction scale. Who knows, sounds like it would work in theory with the capabilities of the SMT, but that's theory. The SMT distributor in San Antonio told me about this sensor substitution trick way back in the day (also in theory, because he sure as hell hadn't done it on any of his SMT installs), and he's got all the SMT goodies and software, but he didnt call it "map hack". Thats a pretty catchy name tongue.gif That's why I asked Lobert if he had the developer's manual because it hints all the little tricks for the SMT boxes. Actually he probably doesn't, that "trick" is generally called the Map Hack and is used for several different devices including the S-AFC and HKS VPC.
Your TPS sensor, MAF sensor and MAP sensor all works on a 0-5 volt DC return line. As such, you can "interchange" them sometimes depending on what you need.
By placing a MAP sensor on the SMT5/6 instead of the TPS, you have changed it's mapping abilities to a pressure-based system instead of a throttle-based one. This gives you the very basic ability to program fuel against manifold pressure, but it isn't always as glorious as you think.
The problem is that TPS mapping on the SMT5/6 is likely meant only for a placeholder, just like it is on the S-AFC. You essentially have "two maps" - one for low throttle and one for high throttle. If you rewire the device so it receives MAP signal instead of TPS, then you now have two fuel maps - one for "low boost" (ie vacuum) and one for "high boost" (ie manifold pressure above a certain threshold you set)
While you may think that this is a great idea, it instead gets a little wierd because you need to map against a LOT of manifold pressures, not just a low/high setting. It doesn't work as well as you think...
Anyways, good luck Lobert. I'm very anxious to hear about the results of your efforts.
