Thursday, December 01, 2005
A few more Megasquirt questions and answers
Is Megasquirt a stand-alone controller or a piggyback system?
It's a stand-alone. Megasquirt can control both fuel injection and spark timing directly. If the original computer in your car only controls fuel and spark, you won't need it anymore. Some buildups do retain the stock computer for other functions, though. Megasquirt does not normally control such things as gauges, ABS brakes, or automatic transmissions, which some factory ECUs control.
Megasquirt is not designed to intercept signals from the stock sensors and send different data to the stock computer, like a normal aftermarket piggyback system. Megasquirt can be configured to fire a second set of injectors while the ECU controls the original injectors, but this is usually only desirable if the original injectors are very unusual and difficult to control.
Can Megasquirt work even if my engine has sequential fuel injection?
Most engines with sequential injection use it mostly for emissions purposes and an ultra-smooth idle. In normal cases, the engine will still run quite happily with the injectors rewired to run in a batch-fire or bank-fire configuration. However, if you have a diesel engine or one that injects gasoline directly into the cylinders, you will need to keep the sequential injection. Currently you will not be able to use Megasquirt with this sort of system, although this is likely to change in the future.
What do I do with my MAF sensor?
Megasquirt is normally a speed-density system and does not need a MAF sensor. Instead it uses a MAP, manifold absolute pressure, sensor. You can remove the MAF sensor unless you also have the stock ECU onboard and the stock ECU needs it. It is possible to program Megasquirt to work with some types of Ford MAFs, but this is only necessary for a few special applications.
Will Megasquirt pass an emissions test?
That depends on what emissions tests are required of your car. If you live in California or other places with similarly strict visual inspections, Megasquirt will be trouble. Megasquirt does not have a CARB EO number, and it has enough potential for mayhem that it is not likely to ever have one. California emissions inspectors will not certify your car if they find you are using a Megasquirt to control the engine.
Many Megasquirt users report being able to pass a sniffer test with careful tuning. If everything on your engine is functioning OK and you have not installed mods that would make passing a tailpipe test difficult, this kind of test should be no problem for normal emissions standards. If your car needs to comply with extremely stringent standards such as ULEV or PZEV, tuning to pass a tailpipe check will be more difficult.
Many states test OBD-II equipped cars by connecting the stock ECU to a diagnostic computer. For this test to work, the stock computer must be in place, functioning, and not detect any problems. Of course, the stock computer need not actually be controlling the engine for it to report that everything is functioning. Some of them will not put out any codes if they are simply hooked to stock sensors and the sensors are not reporting any problems. Others may require connecting the computer to resistors in place of the stock injectors so the computer will "think" it still has a full set of injectors.
How hard is it to solder this thing together?
I had almost no soldering experience prior to assembling one of these things, but I got it assembled in about eight hours of soldering.
Do I need any programming skills to run this?
Not really. While the assembly is do-it-yourself, the programming has already been done.