[Gmecm] Failing Calif SMOG

[Avery Nisbet]

What kind of exhaust are you running?  H,X, or Y pipe?

Can you move the O2 sensor to the other side or after the exhaust's
join? or get a wide band and log some runs compared to the ALDL
output.

Could the tech give you numbers on HC's HydroCarbons?  Also how were
your Nox? Those will tell us a little more about rich or lean. Over
advanced or under advanced.
Carbon-monoxide is more of a incomplete combustion thing(a few things
can cause it).


How did the Tech put the engine into "fast idle"?
-Avery



On Tue, Aug 30, 2011 at 3:27 PM, Roger and Carol <rogerancarol at cox.net> wrote:
> ?94 Chevy 5.7L V8 with Edelbrock MPFI. ECM 16171199, with EPROM tuned by
> Edelbrock, based on broad cast code BDUY.
> The engine failed recent SMOG test with a CO reading on the ?high idle? test
> of 2.06% at 2635 RPM; max CO allowed is 1.00%.
> CO at ?idle? measured .03%, at 649 RPM, which was well within the limit.
> My BLM?s at 2500 RPM read 130 on my scanner, which I believe means the
> PROM?s fuel map is biased ?lean?, and the ECM is compensating as it should.
> I?m confused as to how the BLM?s can indicate that the ECM has control over
> the fuel ratio but the exhaust gas (SMOG test machine) indicates a ?rich?
> condition, which results in high CO? Note that CO at idle was .03%, which is
> well within the limit, thus at idle fuel mixture is correct.
> This engine has only one O2 sensor, which is located in the driver?s side
> exhaust manifold (manual trans applications only). Does it make since that
> the cause for the rich condition is probably associated with the
> passenger-side only (not any sensor that affects all cylinders, like the
> MAP), and therefore not ?sensed? by the O2 sensor? Since I have Edelbrock?s
> MPFI, I think it could be an injector problem on the right bank only.
> Edelbrock?s system is batch fire, by the way. Inputs from ?fresh? minds
> would be appreciated.
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