Idle too high. How do I adjust

[Shannen Durphey]

I have seen speed generators for marine applications.  They are small
paddlewheels which generate an a/c signal.  The MEFI ecm's will accept a speed
sensor input, and documentation describes the sensor as a "boat speed sensor."

I dunno that I'd actually use one on a boat ecm conversion though.  After
driving my car with the marine programming, it seems like all a person needs to
do is work on tables around idle and WOT.  Most of the items like decel
spark/fuel, Decel fuel cut out, and fuel enleanment are unnecessary since
there's very little to drive the engine after the throttle is closed.  Also, I
dunno if load is going to be that great in a marine application.

Is there any chance the 4200 rpm limit is caused by the drive/prop combination? 
I'm not a marine mechanic, but I know guys are always changing props based on
the top rpm they want the engine at.  4200 for a truck big block is fairly high,
so there may be other issues in the programming which are showing up.

The park/neutral switch can be left disconnected, but I'd use a manual trans
calibration as a base.

I would like to see pictures of the O2 installation.
Shannen

Bob Valentine wrote:
> 
> Yes, the VSS is the speed sensor.    The VSS has a lot to do with idle
> since in a car app the ECM uses it to determine accel/decell/stop.  No VSS
> and/or no park/neutral usually results in some wierd driveablity problems.
> 
> What sort of data is the scantool saying at WOT?
> 
> Have any pictures of this you can post somewhere?  Sounds interesting.
> 
> -> Bob Valentine
> -> bob at tecmark.com
> 
> At 12:57 PM 9/5/2001 -0500, you wrote:
> >Im not up on all the lingo, but Im assuming the VSS is the speed sensor. If
> >so, I do not have it connected to anything. Are you thinking this effects
> >upper rpm or idle? I dont have the gear selector connected either. Isnt this
> >a neutral/park indicator? Could the VSS limit the rpm to 4200?
> >
> >As far as the ecm and the elements. I realize its a risk, but I use my boat
> >on a fresh water only and generally for a few hours at a time and is kept in
> >dry storage. I did enclose the ecm in an aluminum box and packaged it in
> >styrofoam. Its not water tight, but put in a place that should stay dry. I
> >realize its a risk, but I thought Id give it a try.
> >
> >For those interested in the conversion, it was a straight bolt in, other
> >than having to mount the o2 sensor in one of the manifolds and the electric
> >pump/return line.
> >
> >> ----------
> >> From:        Gregory A. Parmer[SMTP:gparmer at acesag.auburn.edu]
> >> Reply To:    gmecm at diy-efi.org
> >> Sent:        Tuesday, September 04, 2001 2:41 PM
> >> To:  'gmecm at diy-efi.org'
> >> Subject:     Re: Idle too high. How do I adjust
> >>
> >>
> >> > I have repowered my boat with a '90 rv tbi 7.4. It has a 747 ecu and
> >> works
> >> > nicely, other than the idle. The boat likes a 500+/- rpm idle and it's
> >> > currently idling at 800. What can be done to adjust it? (Ive tried
> >> backing
> >>
> >> Is VSS connected?  To what?...I dunno either, but idle problems are often
> >> related. It might be sufficient to "fake it" once so that the IAC can
> >> reset itself. After that is covered, idle speed is set in the chip. See
> >> programming 101 on the website for more info.
> >>
> >> -greg
> >>
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