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From: kludge@panix.com (Scott Dorsey)
Newsgroups: rec.autos.tech
Subject: Re: 1998 Ford 4.2L V6 idle issue
Date: Sat, 21 Jun 2025 12:25:47 -0400 (EDT)
Organization: Former users of Netcom shell (1989-2000)
Message-ID: <1036meb$a80$1@panix2.panix.com>
References: <d4dfef03090f2ae91c59680f6a20d6e89f623105@i2pn2.org> <1034ilk$8jua$2@dont-email.me> <1034l0o$sfo$1@panix2.panix.com> <ee35c5282ece3b1314348cfb70d5e0ba96113ae2@i2pn2.org>
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UFO <techforce@nospam.gmx.com> wrote:
>Thanks, I got a code reader for 21 bucks at Wallymart.
>
>It fit on the plug under the dash, and with the eng running it indicated: 
>P1537, P1538
>Found this post online with some things to look into.

Ignore the second code.  The first code tells you that the computer thinks
the intake manifold runner isn't moving.  

Some engines will use engine vacuum to move these, some will use a servo.
if yours uses engine vacuum, the first step is to check for vacuum leaks
which you should have done already anyway..

The next step is to make sure they do move freely by hand, and THEN to
check out the position switches that let the computer know that they are
open or closed.

>Meanwhile, I replaced the serpentine belt as the used car dealer had ordered 
>it
>and said I could have it.
>
>I noticed a slight clicking coming from near the alternator area on the pass 
>side
>after the new belt was on and eng running. As the eng warmed up, the 
>clicking seemed
>to diminish, almost sounded like a bearing in the really early stages of 
>EOL.

Did you replace the tensioner at the same time as the belt?  If you squirt
a little Super-Lube into the tensioner bearing, does the noise stop? 

>Last week the truck sat unstarted for 3 days, and it started up ok but
>this RPM drop happened after only 15 seconds, then as before, it recovered 
>fine
>and I moved the truck into the workbay and did the serpentine belt job.

Have you looked for vacuum leaks yet?  You should check plugs too (which
won't be causing any of your problems but is a good idea on a vehicle with
no maintenance history).

>Wondering if it could be the alternator bearing, or the idler or tension 
>pulley
>once in a while binding, slowing down to nearly a stall?

No, that has nothing to do with your stalling problem.  That is a different
issue.  Find out why the computer thinks the runner isn't moving.
--scott


-- 
"C'est un Nagra. C'est suisse, et tres, tres precis."