What does this board do?
Marc Piccioni’s new TPI adapter board works with 1986 to 1989 Corvettes, Firebirds, and Camaros with the TPI injection as a substitute for the “165” ECM; they are blue colored but otherwise very similar to the earlier TBI adapter board. These boards are meant to be used with Megasquirt-II only. In addition to the adapter board and Digikey parts, we currently recommend need a ‘747 ECM from a TBI truck for the mating connector and case. The ‘747 connector and internals are slightly different from the ‘165 ECM, which makes installing the adapter board easier, so we recommend using the 747 ECM as a donor ECU.
Assembling the TPI Adapter Board
Bill of materials:
Building and Configuring the MS-II
If you’re assembling your MegaSquirt-II from a kit (Part# MS230-K):
That’s it– you’ve got your Megasquirt-II Engine Management System fully prepared to work with the adapter board.
If you’re using a DIYAutoTune.com MS230-C or MS2357-C MegaSquirt-II Assembled ECU:
Fitting It in the Case
The TPI adapter board is designed to squeeze both the adapter and the Megasquirt into the stock case. The Megasquirt board is supported by the DB37 connector at one end and the other end is supported by the side rails.
Megatune Ignition Configuration:
Dwell is very low; try around 2 ms and adjust as needed.
More information on setting Trigger Offset:
You must also set the initial position of the trigger (called the ‘trigger offset’), then check it using the Trigger Wizard in MegaTune (Tools Menu). The trigger offset setting will vary according to your distributor position (where it is in rotation) but you’ll need to set it properly… Basically you use the Trigger Wizard and adjust the ‘trigger offset’ and/or twist your distributor until the advance number in the Trigger Wizard matches what you’re reading with your timing light. The +/- buttons on the trigger wizard will adjust your trigger offset. You’ll need to use these buttons and a timing light to make the number on your light, and the big number on the left in the Trigger Wizard, match up.
Here’s the information on this direct from the MegaTune Manual:
Before tuning your advance table, be sure to use a timing light to verify that your ‘trigger offset‘ is calibrated. Changing the Trigger Offset in MegaTune will not change the displayed advance, instead, it changes the actual advance as seen with a timing light. Your goal is to make these two match.
To do this, get your engine warmed-up (otherwise the timing moves as the temperature increases) and idling, then use a timing light to verify to be certain your actual advance as shown by a timing light equals your the advance display on the advance gauge in MegaTune. (8′ in this case). (Note that positive numbers denote BTDC, and negative numbers denote after TDC.)
Image courtesy of Bowling and Grippo
Cranking Timing Bypass
Some HEI modules – mostly aftermarket replacements – have a problems if you don’t turn off the bypass signal while the engine is cranking. TBI ECUs have a wire that sends the ECU a cranking signal. This automatic bypass feature is not present on the TPI ECUs, but the board has the parts to add this feature. If you are having problems losing spark while cranking, take the wire included with the adapter board and add it your harness connector on pin C9. Connect this to the ignition key on a terminal that gets 12 volts in the Start position but not the Run position. This will allow the bypass feature to function normally.
Spare outputs and inputs
The adapter board lets you control several features besides fuel and ignition. Two of these can be accessed through the spare port configuration screen in TunerStudio. The acceleration LED (PM4) now controls either the shift light or the torque converter lock-up. While the factory torque converter lock-up is controlled by the vehicle speed sensor (among other things), the MS-II does not have a vehicle speed sensor input. Instead, you can control it so that it is active above a certain RPM, and you can also set MAP reading or throttle position as a secondary condition. The FIDLE port controls the cooling fan.
For knock sensing, you can use the factory knock sensor on the engine.
The board does not control emissions devices like the EGR or canister purge.
If the end application is equipped with an automatic transmission that has a lock up torque converter, it is the end user’s responsibility to ensure that torque converter lock up does not occur in park, reverse, neutral or 1st gear. The transmission’s internal wiring should prevent the TCC from locking except in 4th gear, but if this wiring is damaged or modified, the adapter board will let you engage the lock up torque converter at any time.