EGR disabled and Knocking

[Shannen Durphey]

Brent wrote:
> 
> I disabled EGR (1b3 set to 00) on my stock '91 C2500 350/A4, 7747.   When I
> took it for a test drive it knocked alittle during cruise and light throttle
> accel.   Should disabling EGR cause it to knock?  
Yup, often.

>I thought it would run the
> same as with EGR on, 
Nope.

>seeing how EGR adds spark and removes fuel.
Yup.  

How's that for an answer? : )  You forgot to put "and slows down
combustion by the addition of a non-combustible gas" to the end of the
last sentence.  

If ya slow down the combustion by adding Exhaust Gas, what do you have
to do to put the best part of the burn in the right place?  Start it
earlier by advancing the spark.  If you remove some of the air in the
fuel/air mix by adding EG, what do you have to do to keep the mixture
from being too rich?  Remove fuel.

Course that's just to give you an idea how to relate to the EGR
tables.  Understanding EGR, combustion, and the IC engine is, well,
more involved.
Shannen
> 
> Regards
> BrentH.
> 
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