[Gmecm] Ridiculous MAF MAP responses.

[Jay Vessels]

Hi there!

I've answered this sort-of out of order, so bear with me.

 > I am just
 > appalled at the responses I have gotten from other members.

I'm not surprised at the response when you mentioned money, and I'm not 
surprised at your reaction.  Here's the deal:  Many people on this list 
have been burned because their hard work was exploited by someone else 
for profit.  There are a LOT of people on this list that have put a LOT 
of time researching, experimenting, and studying these systems and the 
wealth of the collective knowledge here (both on the list and in the 
archives) is staggering.  People feel slighted when someone farms the 
list of information and uses that to make money.  Is it okay to make 
money working on GMECM stuff?  Yes.  Is it okay to use knowledge gained 
from this list?  Sure, but don't forget to give back what you learn 
outside of the list.

Take your MAP->MAF translator idea.  You've gotten a mix of responses. 
Take that, mix it with some reading of the archives (pay attention to 
how MAF systems work, and how MAP systems work), come back with some 
questions to clarify points you may not get the first time, and then:

Take some data.  Model it on your PC.  Build something.  Try it.  Post 
the results.

Hook a MAP sensor up to your car and hitch it to your laptop.  Gather a 
big pile of data from the ECM and your MAP sensor, stuff it into a 
spreadsheet, and see if you can figure out a relationship given the 
information you have on how GM MAF and MAP systems work.  Write up a 
piece of code (in Matlab, Excel, C, whatever) to test your theory.  Get 
more data and see if it fits.

Show the list your work -- you'll get a lot more constructive feedback 
when you show "Here's what I've been doing and this is what I think is 
happening" rather than "Tell me everything I need to know".

It's a lot of work but I think it will be worth it.  It's also the only 
way you'll get your MAP->MAF box working.

 >My original intent to charge $100 bucks was to be
> a fully assembled conversion kit. 

This is not meant to discourage starting a small business, but:

Buying the parts, programming the ROM(s), assembling the kits, writing 
and printing the documentation, testing, shipping, and handing tech 
support calls and warranty concerns is not cheap.  "I can build this all 
myself" may well be true but if you add up your time per box divided 
into the cash left just after parts procurement, and you're better off 
mowing lawns.  Add in the additional time for tech support (and people 
will have questions), warranty concerns ("You sent me a junk box!  I 
want another one or my money back!  If you don't I'll sue!"), and you 
have to really *want* to do it as it's a charity case.

Oh yeah, the lawyers.  What happens if somebody wrecks their car and 
decides it's because your box failed?  True or not, welcome to legal 
hell.  It's mind-boggling how much THAT will cost, but I'd wager you'll 
spend a good $100k defending yourself ONCE.

Which is why you need to indemnify yourself, and one way to do that is 
have your device manufactured by a local company.  They'll want a 
guaranteed minimum order (probably in the hundreds of units) so you'll 
have to front some money.

It's cool to try to build something that people want, perusing a hobby 
and making money at it.  It's possible to do, and done right you can 
turn it into a strong business.  I just want to make sure you consider 
all the potential pitfalls, and have a plan to dodge them.

Building and selling electronics is not as simple as, say, selling a 
custom bracket or pretty add-on.  The electrical system in an automobile 
is a very harsh environment.  If you don't have a plan to handle ESD, 
RFI, reversed polarity, and hard shorts to ground and power then your 
design needs rework.  If you don't know what the term "alternator load 
dump" means or how to handle it, you've got more reading to do.

An example of an automobile electronics project that went right (at 
least, from an outsider-looking-in view) is the DIY-WB project.  I'm 
sure those guys can tell you a lot more than I can about successfully 
pulling off a small-quantity auto electronics project for the masses.

Jay Vessels
1982 Chevrolet S-10 Sport, 2.8V6 TBI
1984 Chevrolet S-10 Blazer Sport, 2.8V6 carb. (for now)