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From: dsm@vaxine.UUCP (Doug Mildram)
Newsgroups: net.auto.tech
Subject: Causes of pinging
Message-ID: <1@vaxine.UUCP>
Date: Sun, 24-Nov-85 16:50:22 EST
Article-I.D.: vaxine.1
Posted: Sun Nov 24 16:50:22 1985
Date-Received: Thu, 28-Nov-85 08:03:34 EST
Organization: Automatix, Inc., Billerica, MA
Lines: 34

This group is starting to get interesting, when topics are not brand-specific.

Re: pinging.  So many things affect preignition (pinging)!
1)  Combustion temperature, which is controlled by engine design, the cooling
system, the plug heat range,...  More heat = more likely to ping.

2) Advanced engine timing.  The pinging explosion reaches the head too soon,
reverberates through the cylinders, and slams the open valves back home.

3) engine octane.  Poor octane gas burns too quickly, causing the above.

4)  Bad or disconnected EGR valve.  A working EGR valve, by recombusting
half-burned gases, lowers combustion temperature by "weakening" the intake
mixture.  This allows cars to run nice and hot (efficiently) and not ping when
you boot it.  It also signals the end of simple, powerful engines.

5) carbon deposits on the head and the top of the piston GLOW and ignite the
new charge too soon.  This is a good reason to clean surfaces during a valve
job.  If you have a carb, you can battle this with an "internal steam clean"!

INTERNAL STEAM CLEAN:  get a pint or a quart of water in a pourable container.
Take the air cleaner cover off and get a good grip on the throttle.  The car
must be hot.  Rev the car up to 3 grand or so, and pour water down the barrel
of the carb, fast enough to slow the engine down, but not fast enough to stall
it out.  Use the throttle freely to keep it going.  If the car stalls and
floods, open the throttle and wait a few.  Sounds wild, but I have cured
(temporarily, at least) a few pingers this way.

So you can combat ping in many ways. I'd rather buy premium than retard timing.


ucbvax----allegra---\                            Doug Mildram (dsm)
                     ----encore---vaxine--dsm    Automatix, Inc.
           decvax---/                            Billerica, Mass.