[Gmecm] Acquiring ECM schematic

[Jay Vessels]

Hi there!

charles at taildragger.info wrote:
> Seems like there'd be a market for new ECM's that connect to all the
> factory wiring, but use modern electronics.  Plus maybe do things a little
> better (bigger BLM map, etc.) and with better instrumentation.
> 
> I don't think there's anything like this though, is there?  I mean,
> besides DIY plans.

The biggest obsticles to building a "superECM" as suggested on a large 
scale are many, including potential patent infringement and emmissions 
certification.  I don't see a market for it, since most customers want a 
replacement part (i.e. don't care about better code or tuning tools) or 
they want a full-custom aftermarket ECM.  Those of us wanting a better 
GM ECM to hack/tune/play with are relatively few and our needs are 
served reasonably well with what we already have or are willing to build.

There is a group on Thirdgen rewriting the TBI code, but it runs on a 
stock GM ECM.

There are plenty of people willing to sell you an aftermarket ECM, like 
FAST.  They are all DIY tuning (with various levels of software and 
support) and most will run old and modern engines in many states of 
tune.  These are targeted mainly at the aftermarket performance crowd, 
and as such are usually tilted at those with hotter than stock engines, 
nitrous control, boost control, etc.  They are a good choice for cars 
whose ECMs are not hacked nearly as completely as GM offerings and for 
owners that do not want to go the DIY route on hacking/tuning.

The downsides are cost, availability in the event of failure (AutoZone 
stocks most common ECMs but not a FAST / Holley / etc. one, so don't 
break down somewhere with an ECM failure), and some limitations with 
handing some of the things that GM ECMs handle out of the box.  They are 
not pin-for-pin compatible but that's an easy problem to solve.

The biggest problem for many may be that they are not 
emmissions-certified, and I doubt an OBD-II car with such an aftermarket 
ECM would pass (even if it were running clean at the tailpipe) due to 
the OBD-II conversations the test centers have with the vehicle.

Jay Vessels
1982 Chevrolet S-10 Sport, 2.8V6 TBI
1984 Chevrolet S-10 Blazer Sport, 2.8V6 (TBI pending)