NetNews Usenet Archive 1992 #20/NN_1992_20.iso/spool/rec/autos/tech/12650

Internet Message Format | 1992-09-15 | 1.6 KB

Path: sparky!uunet!paladin.american.edu!darwin.sura.net!zaphod.mps.ohio-state.edu!cis.ohio-state.edu!ucbvax!XEROX.COM!Michel_Denber.WBST147
From: [e-mail]
Newsgroups: rec.autos.tech
Subject: Re: 85 chev celebrity
Message-ID: <[e-mail]>
Date: 15 Sep 92 14:03:00 GMT
Sender: [e-mail]
Lines: 25


    "the idle will sometimes become eratic"

Congratulations!  You've got the V6 From Hell!  Once again,
rough/unstable/erratic idling in the GM 2.8L MFI engines from 85 through 88 is
due to marginal/defective MAF sensors and a buggy fuel control program.  GM has
an upgrade program on this that involves bagging the MAF sensor entirely so the
engine gets all its data from the MAP sensor instead, and replacing the ECM
PROM.  According to an article in "Motor" last year, most of these systems
developed problems by 50K miles.  A quick test is to give the MAF sensor a
whack with your hand.  If the idle stumbles, you've got it.  The program is
supposed to be "on customer demand" or whenever one of these engines shows up
for service.  When my '88 Celebrity died last month, the dealer fixed the
problem (bad crank sensor) *and also* did the MAF -> MAP mod *without telling
me*.  (They also screwed up my power steering, and left off a few nuts and
bolts, but that's another story).  Oh yes, I assume you've checked other more
obvious causes of rough idle like EGR valve operation, PCV, and IAC.

Your code 42 does *not* mean no tach signal.  If you had no tach signal, the
engine wouldn't run at all.  My book is home, so I can't give you any more
detail at the moment.

            - Michel

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