The quest for more speed....

[Shannen Durphey]

Scot Sealander wrote:
> 
> Shannen Durphey wrote:
> 
> > Ross M's question about the old ECM got me thinking...
> > It seems like a faster ecm will make for a better running engine.
> 
> Probably not a good assumption.....  An 8 bit controller running at 1 Mhz
> busspeed can do the job.  Witness the C3's.  There may be some
> improvement at
> over 4800 RPM or so with a faster ECM.  But the question is really quite
> broad.  What do you mean by better running?

Good question... I was thinking of idle quality, and driveability.  I
don't know if the idle quality got better because of the faster
computer, or because better idle control strategies were used.  But
simple things did improve between certain ecm's.  Idle speeds could
stay high for long periods on older units, but this seemed to be
corrected by 88 or so. Early FI cars could be tricked into stalling,
or hiccupping, and newer vehicles are much tougher to fool.  
> 
> > Is there any way to "boost" ecm speed?
> 
> GM did this for you.  Got a C3?  Move to a P4.  Got a P4?  Move to a P6.
This is the road most taken,  but each trip involves learning to tune
a new ecm.  

> But most don't really calculate the fuel or timing any "faster" than the
> previous
> generation did.  
That's very interesting. How about IAC control?

>The faster ECM's were needed because of more overhead.

Overhead as in added systems not previously tied in to the ecm?   If
an ecm were pulled from a vehicle with HVAC, cruise, and instrument
panel tied in, and installed in a car with none of these added
systems, would it be a valid goal to reduce the unnecessary code?  Do
you think it would result in any gains?
> 
> Scot Sealander    Sealand at clarityconnect.com
Thanks,
Shannen