Megasquirt reality check!

[jdbubb at ix.netcom.com (Dan Bubb)]

Since there seems to be a surge of interest in Megasquirt and since I feel I'm partly responsible because I've been hyping it from day one, I want to take the time to throw some light on the total picture.
I think the MS is a great little system. It's cheap, it's very capable, it has excellent tuning software and there is great support on the Yahoo MS group.

But, having said all that, it's becoming apparent from watching the posts of some people on the Yahoo group and on Vortex that you really need to have more than a basic understanding of how engines work before you can install and tune an aftermarket engine management system.

First there is assembly, wiring and installation. It's easy to bypass these steps by having someone else do them, but even then this is not factory wiring, so to get factory reliability some care needs to taken in crimping or soldering and wire routing to make sure the connections don't fail due to heat, vibration or contact with other components. You need to be able to read a basic schematic and convert that into actual contacts, connectors and sensors. What's the worst that can happen if a solder joint on the PC board fails or a wire splits due to an overdone crimp? 

So, you've gotten the unit installed and it's time to start you car. What if it doesn't start? Now you have to trouble shoot the installation, make sure MS is operating correctly and all the sensors are giving reasonable values. Of maybe you just need to tweek some tuning parameters. Are you familiar enough with the system to trouble shoot it or know what parameters to change?

A very common problem with MS installations is not being able to get a clean tach signal. There are lots of things to change to fix this problem, but do you have the understanding to know what to change?

Then there is the actual tuning once the car is started. VE table, injector setup including the possible need for PWM if the injectors are low impedance, Required fuel and injector control setup. Plus all the enrichments; cranking pulse width, afterstart enrichment, EGO setup, warmup enrichment and acceleration enrichment.
There are strategies for approaching all these tuning parameters, but you need to understand how the enrichment works to be able to tune it.

I've seen alot of people request maps or tuning setups from other people with similar engines. It is my experience that exchanging maps will get you a base map that will allow your engine to run. There are too many variables from engine to engine that will change a VE table or acceleration enrichment. As an example, just changing to a different cam can change a VE table entry by 30%! Changing cam timing will change the A/F ratio enought to require tweeking VE table entries. The same can be said about the various VE table generators available for MS. They'll get you a starting point! The MS really needs to be tuned to your engine!

In the end I'll help as much as I can, as I'm sure will other listers, but there are things that cannot be done through e-mail or over the phone. If you don't have a good understanding of the fuel requirements of an engine and don't understand most of the documentation available on the Yahoo group, it may be best to pass on installing MS or at least take the time to understand the documentation before attempting installation and (effectively) disabling your car and painting yourself into a corner.

I'm not trying to inhibit anybody's enthusiasm in our sometimes headlong rush to more power, but I've heard of more than one guy with a good basic understanding of engines that doesn't know where to start with tuning his engine or thinks he's done tuning his car and wonders why he's only getting 10 MPG!

Maybe I'm being a pessimist and everybody's on top of this. I hope so!

Dan