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Path: utzoo!linus!philabs!seismo!harpo!eagle!hou5h!hou5g!hou5f!hou5e!tgg
From: tgg@hou5e.UUCP
Newsgroups: net.auto
Subject: Re: SLICK 50 info summaries and a Honda question
Message-ID: <883@hou5e.UUCP>
Date: Tue, 13-Dec-83 11:29:16 EST
Article-I.D.: hou5e.883
Posted: Tue Dec 13 11:29:16 1983
Date-Received: Thu, 15-Dec-83 01:01:18 EST
References: <696@qubix.UUCP>
Organization: AT&T Information Systems Laboratories, Holmdel, NJ
Lines: 23

>... I noticed that it started pinging under only
>moderate acceleration.  The timing is OK.  I just changed spark
>plugs.  I also try super unleaded gas, and use lower gear to run
>engine in higher rpm.  But nothing helps.  I wonder if the vacuum
>advance is too much under moderate acceleration.  I like to try
>reducing it, but don't know how.  I appreciate if anyone has any
>idea to solve this problem.  Thanks in advance.

On several cars I have corrected obnoxious pinging that has no other obvious
cause by repairing/modifying the EGR system. Recirculated exhaust gas tends
to lower combustion temperatures by being an inert displacement gas and as
a byproduct also reduces knocking (and power and mileage, etc.). A lack of
EGR (via stuck valve, faulty logic or deliberate modification) on newer cars
tends to produce knocking because the cars are tuned within a gnat's eyelash of
knocking to begin with to produce the best economy/power possible.

Hondas seem to be particularly prone to partial or full EGR failure. An old
civic (~'79-'80) and a new accord ('83) both had a stuck EGR valve and pinged
like crazy. Unstuck valve - pinging stopped. Hondas are really wild in the
emissions dept. - two stage EGR valves, a sensor that tells the logic if the
car is over 15mph (emissions are stated in grams/mile, after all), three stage
carbs., 3 (or more) valves/cyl. and >20 vacuum lines under the hood!
	Good Luck - Tom Gulvin		AT&T ISL	Holmdel, NJ