[Gmecm] GMECM

[Rick McLeod]

Most all late 80s to early 90s GM V8s ran a single O2
sensor on the driver bank down pipe, doesn't matter
what is downstream in the way of cross-overs, etc
other than if the flow is increased so much that the
sensor can't see enough heat to get warm, it won't go
closed loop, which is a frequent problem in the likes
of F-bodies that get headers added and low restriction
exhausts (which I have and see it go open loop
occasionally). In that case, replace it w/ a heated
sensor to start with to rule that out, will probabally
take care of the problem altogether.
Also, get a data stream view of what the ECM is doing
and see what is going on, is the O2 sensor working,
BLM's close, etc, it may be as simple also as a broken
wire to the O2 when the duals were installed, don't
rule that out.
Good luck

> > I currently have a 1990 Chevy G20 Van. With a V8
> 350 5.7l engine ECM 
> > 1227747
> > 
> > its been running fine until i put dual exhaust on
> it now its not 
> > running 
> > well at all the idle is very rough at idle and
> also at slow speeds 
> > (most 
> > notably when its cold out)
> > 
> > Ive been told by my mecanic i can be a number of
> things but 02 
> > sensors seem 
> > to always come up as my ecu supports 1 o2 sensor
> and with dual 
> > exhause i 
> > should technically have 2 ? Right or wrong?
> > 
> > id like to possibly avoid doing a flash of the
> eeprom as im not 
> > totaly 
> > familiar with it and was hoping that someone may
> know of a solution 
> > to fix 
> > this problem . preferably not a real expensive one
> ive invested 
> > quite alot 
> > of money in this truck and really want it running
> well again
> > 
> > thanks very much for your help -Mike