I thought I'd start this thread for FAQs about the MegaSquirt PNP, and specifically the MSPNP versions out there for the Toyota MR2. If you've got other questions, let me know - if it's likely a lot of MR2 owners will be asking it, I'll add them to this top post.
So, just what is the MSPNP?
The MSPNP is a plug and play, standalone engine management system that lets you control your fuel and ignition, as well as many other functions, such as boost control and cooling fans.
What MR2s does the MSPNP fit?
Currently, the MSPNP is available for 1985-1989 4AGE models, and the 1991-1992 3SGTE models, in both cases for version with a manual transmission only. (Not that we're aware of any SW20 MR2 Turbos that ever left the factory with an automatic, but if you ever find such a unicorn, we can't promise the MSPNP will work for it.) We believe the 1990-1992 JDM MR2 Turbo uses the same pinout as the 1991-1992 USDM version as well.
We have MSPNP models for the '93-'95 MR2 Turbo and first generation models with the AE111 Blacktop 4AGE swap in development, and will make one for the '88-'89 4AGZE models if we can get a suitable test car. Got one we can borrow? Email kevin@diyautotune.com with details.
What about MSPNPs for Toyotas not on the to-do list?
If we have the connector in stock and you can organize a group buy, we can put it on the list. See the MSPNP On Demand program for details. So, if you want one for your 5SFE, Gen 3 3SGTE, or something else not we haven't mentioned, it still could happen.
At present, we don't have the connector for the MR2 Spyder, and it is likely these will need a more expensive, MS3 based option. But it could happen too, if there's enough demand for it.
Does the MSPNP allow tuning in real time?
Yes! You have complete control over your fuel and spark tables, and changes to those take effect immediately. You can tune it while it's on a dyno or while the car is running around a track - although if you're tuning it at Road Atlanta, we recommend wrapping up your tune changes by the end of the back straight, as tuning while going through that chicane before the Suzuki Bridge and then plunging into Turn 12 like a roller coaster can be distracting.
Do people really ask about tuning from the passenger seat while running around Road Atlanta?
Sorry, that's only happened once. We'll try to stick to more common questions from now on.
Do I have to make any changes to my distributor to run the MSPNP?
No. The MSPNP's inputs have been dialed in for the stock distributor pickup signals. You don't have to file teeth off the trigger wheel or anything like that.
Can I remove my mass air flow sensor or vane air flow meter using an MSPNP?
Yes. The MSPNP has a built in MAP sensor, letting you run speed density. This means it has no need of a mass air flow sensor, and you can replace yours with a length of straight pipe if you're so inclined. We've often seen a measureable horsepower gain from this on a dyno, particularly if you have a vane style air flow meter like most MR2s.
You said the MSPNP runs speed density. Does it support other load modes?
Yes. It is possible to set it to use a mass air flow meter, although you will need to generate a calibration curve for your MAF - there's an internal switch that swaps the MAP sensor input for the factory load sensor. It also allows alpha-N operation (using a throttle position sensor for fueling) or even blends of alpha-N and speed density. The software has a special ITB mode that uses the MAP sensor at low throttle / high vacuum and switches to the TPS at high throttle / low vacuum, for those using independent throttle bodies.
Do I need to make any changes to my wiring or sensors to run an MSPNP?
MSPNPs can run a car with all stock sensors and its built in MAP sensor, with one important exception. On an MR2 with forced induction, you'll need to add a post-intercooler IAT sensor. We recommend putting it in between the throttle body and intercooler. Putting it in the manifold is also an option but may make hot starts more difficult.
We include the IAT with the MSPNP models sold for the 3SGTE since its use is required. On the 4AGE model, the IAT sensor is sold separately since you can use the factory sensor for air temperature if you haven't added a turbo.
How much boost can I run with an MSPNP?
All of it. The MSPNP has a 4 bar MAP sensor as standard equipment, which can read up to 44 psi. In the unlikely event that is not enough, it is possible to use an external MAP sensor that reads higher. As long as your fuel system can supply enough fuel and your engine is tough enough to handle it, you can tune for it with the MSPNP.
Can I have two maps in it? Like one for power and one for fuel economy?
The MSPNP has a switch input to allow switching between two fuel and ignition tables. However, we have generally found that a good tuner can produce a table that gets both maximum power and good fuel consumption, so we don't recommend trying to create separate power and economy maps. Good uses for this feature include a pump gas and high octane race gas map, one map for wide open exhaust and a second for tracks that require a muffler, or switching to the second map when a nitrous system is active in order to pull timing and add fuel.
Is the MSPNP emissions legal?
The MSPNP is sold for competition use on race tracks, autocross, drag strips, off road courses, and things that otherwise don't get driven on public roads. Although a correctly tuned MSPNP is capable of relatively low tailpipe readings, a badly tuned one can send emissions through the roof. Consequently, installing one on a street car does not meet Federal emissions rules. If you have to return your race car to street duty, you've got to unplug the MSPNP and go back to the stock ECU to stay street legal.
If you're outside the USA, you'll have to check what your laws are over there. Other countries are sometimes more lenient.
Where are MSPNPs made?
The case and PCBs are made in the USA, and all assembly work is done in the USA as well. The connectors, transistors, and other electronic components come from all over the world, so they can be advertised as "Assembled in USA" but not "Made in USA."
Can I use an MSPNP to convert to distributorless ignition?
Yes. The stock distributor pickup on these cars does have a cylinder identification sensor so it can be used to trigger a distributorless ignition. We've included a 15 pin plug on the back of the unit with two spark channels that can be used to run a wasted spark ignition or fire a coil on plug set of coils in pairs.
Where does the MSPNP fit in the MegaSquirt family? Is it a V3.0 or V3.57?
Neither. At its core, the MSPNP uses a MicroSquirt Module. We've added an extra circuit board of our own design to expand the MicroSquirt Module's list of features.
The MSPNP has four plugs on it, but there's only three on my stock ECU? What gives?
We opted to use a connector with extra plugs on it so that we could use the same connector and case for a wide variety of cars. You just leave out one plug.
So, just what is the MSPNP?
The MSPNP is a plug and play, standalone engine management system that lets you control your fuel and ignition, as well as many other functions, such as boost control and cooling fans.
What MR2s does the MSPNP fit?
Currently, the MSPNP is available for 1985-1989 4AGE models, and the 1991-1992 3SGTE models, in both cases for version with a manual transmission only. (Not that we're aware of any SW20 MR2 Turbos that ever left the factory with an automatic, but if you ever find such a unicorn, we can't promise the MSPNP will work for it.) We believe the 1990-1992 JDM MR2 Turbo uses the same pinout as the 1991-1992 USDM version as well.
We have MSPNP models for the '93-'95 MR2 Turbo and first generation models with the AE111 Blacktop 4AGE swap in development, and will make one for the '88-'89 4AGZE models if we can get a suitable test car. Got one we can borrow? Email kevin@diyautotune.com with details.
What about MSPNPs for Toyotas not on the to-do list?
If we have the connector in stock and you can organize a group buy, we can put it on the list. See the MSPNP On Demand program for details. So, if you want one for your 5SFE, Gen 3 3SGTE, or something else not we haven't mentioned, it still could happen.
At present, we don't have the connector for the MR2 Spyder, and it is likely these will need a more expensive, MS3 based option. But it could happen too, if there's enough demand for it.
Does the MSPNP allow tuning in real time?
Yes! You have complete control over your fuel and spark tables, and changes to those take effect immediately. You can tune it while it's on a dyno or while the car is running around a track - although if you're tuning it at Road Atlanta, we recommend wrapping up your tune changes by the end of the back straight, as tuning while going through that chicane before the Suzuki Bridge and then plunging into Turn 12 like a roller coaster can be distracting.
Do people really ask about tuning from the passenger seat while running around Road Atlanta?
Sorry, that's only happened once. We'll try to stick to more common questions from now on.
Do I have to make any changes to my distributor to run the MSPNP?
No. The MSPNP's inputs have been dialed in for the stock distributor pickup signals. You don't have to file teeth off the trigger wheel or anything like that.
Can I remove my mass air flow sensor or vane air flow meter using an MSPNP?
Yes. The MSPNP has a built in MAP sensor, letting you run speed density. This means it has no need of a mass air flow sensor, and you can replace yours with a length of straight pipe if you're so inclined. We've often seen a measureable horsepower gain from this on a dyno, particularly if you have a vane style air flow meter like most MR2s.
You said the MSPNP runs speed density. Does it support other load modes?
Yes. It is possible to set it to use a mass air flow meter, although you will need to generate a calibration curve for your MAF - there's an internal switch that swaps the MAP sensor input for the factory load sensor. It also allows alpha-N operation (using a throttle position sensor for fueling) or even blends of alpha-N and speed density. The software has a special ITB mode that uses the MAP sensor at low throttle / high vacuum and switches to the TPS at high throttle / low vacuum, for those using independent throttle bodies.
Do I need to make any changes to my wiring or sensors to run an MSPNP?
MSPNPs can run a car with all stock sensors and its built in MAP sensor, with one important exception. On an MR2 with forced induction, you'll need to add a post-intercooler IAT sensor. We recommend putting it in between the throttle body and intercooler. Putting it in the manifold is also an option but may make hot starts more difficult.
We include the IAT with the MSPNP models sold for the 3SGTE since its use is required. On the 4AGE model, the IAT sensor is sold separately since you can use the factory sensor for air temperature if you haven't added a turbo.
How much boost can I run with an MSPNP?
All of it. The MSPNP has a 4 bar MAP sensor as standard equipment, which can read up to 44 psi. In the unlikely event that is not enough, it is possible to use an external MAP sensor that reads higher. As long as your fuel system can supply enough fuel and your engine is tough enough to handle it, you can tune for it with the MSPNP.
Can I have two maps in it? Like one for power and one for fuel economy?
The MSPNP has a switch input to allow switching between two fuel and ignition tables. However, we have generally found that a good tuner can produce a table that gets both maximum power and good fuel consumption, so we don't recommend trying to create separate power and economy maps. Good uses for this feature include a pump gas and high octane race gas map, one map for wide open exhaust and a second for tracks that require a muffler, or switching to the second map when a nitrous system is active in order to pull timing and add fuel.
Is the MSPNP emissions legal?
The MSPNP is sold for competition use on race tracks, autocross, drag strips, off road courses, and things that otherwise don't get driven on public roads. Although a correctly tuned MSPNP is capable of relatively low tailpipe readings, a badly tuned one can send emissions through the roof. Consequently, installing one on a street car does not meet Federal emissions rules. If you have to return your race car to street duty, you've got to unplug the MSPNP and go back to the stock ECU to stay street legal.
If you're outside the USA, you'll have to check what your laws are over there. Other countries are sometimes more lenient.
Where are MSPNPs made?
The case and PCBs are made in the USA, and all assembly work is done in the USA as well. The connectors, transistors, and other electronic components come from all over the world, so they can be advertised as "Assembled in USA" but not "Made in USA."
Can I use an MSPNP to convert to distributorless ignition?
Yes. The stock distributor pickup on these cars does have a cylinder identification sensor so it can be used to trigger a distributorless ignition. We've included a 15 pin plug on the back of the unit with two spark channels that can be used to run a wasted spark ignition or fire a coil on plug set of coils in pairs.
Where does the MSPNP fit in the MegaSquirt family? Is it a V3.0 or V3.57?
Neither. At its core, the MSPNP uses a MicroSquirt Module. We've added an extra circuit board of our own design to expand the MicroSquirt Module's list of features.
The MSPNP has four plugs on it, but there's only three on my stock ECU? What gives?
We opted to use a connector with extra plugs on it so that we could use the same connector and case for a wide variety of cars. You just leave out one plug.
