Easy way to tell on a bad MAP: "Baro" reading on the scanner. It should be
close to what your actual barometric pressure is - you can easily check that
with a weather website in your area. Normally, 29.0 - 29.5 is the norm with
30" during a storm (high/low pressure changes). If it's at 31" or
27"...something is wrong with the sensor.
The sound you described also strikes a flag - what's the engine vacuum at
idle, 1500rpm, normal cruising, and at WOT? Reason for asking is you can
tell if a cat is plugged up by checking the vacuum. If it's plugged up, the
vacuum under WOT will not go down to "0" and will rise slowly but steadily
(WOT run on the Highway or lonesome street is a goot area to test this).
Does your Elmscanner allow for saving data log files (Sensor data) and if it
does, can it be saved into a standard file to read/email?
- Bernd
-----Original Message-----
From: Steve Preston [mailto:steveophonic@yahoo.com]
Sent: Saturday, July 21, 2007 8:36 PM
To: dakota-truck@dakota-truck.net
Subject: DML: Was checking transmission line pressure,now other stuff.
(Bernd)
TPS is rock solid. I checked it with an ohmmeter
first,then double-checked with the Elmscan when I got
it. Couldn't duplicate a bad spot or a jump in
resistance in the wrong direction at all. Smooth.
The MAP is a possibility. I don't remember seeing a
reading from it.
The other day,I slid the rear slider open and listened
to the engine while I drove up a steep hill,and swore
I heard it sputter,but the sound of the exhaust is bad
anyway. It has like a "listening through a tin can"
sound. There is no rattling like the brick loose or
anything,but the tone of the exhaust just has a
metallic,hollow sound. My own 3.9 Dak I used to have
never sounded like that,I don't think.
I probably need to see what's going on with the engine
vacuum. I have a new digital manometer for HVAC
use,maybe that'll work. Reads in inches of water
column. Wish it was analog though.
I'll try to pick off your list of suspects one by
one,Bernd. Thanks!
Steve P.
--- "Bernd D. Ratsch" <bernd@dodgetrucks.org> wrote:
>
> TPS can also cause the erratic shift...normally only
> at light throttle
> cruising speeds but it can cause problem shifts if
> there's a "dead spot" in
> the TPS circuit. If you have an analog volt meter
> (simple needle on a
> gauge) you can measure the TPS and watch the
> "sweep". Connect the + side of
> the meter to the TPS signal (back probe the sensor)
> and the - side to
> ground. Key ON/Engine OFF, move the throttle and
> watch the needle (it will
> go from about .5v to 4v as you move the throttle).
>
> Things that can cause erratic shift (electronics
> wise): TPS, Governor
> Pressure Solenoid, TCC Solenoid, Pressure
> Transducer. Erratic surging: IAC,
> TPS, MAP, actual tune of the engine (plugs, wires,
> cap, rotor)...so if you
> check all the basics first - you'll narrow it down
> rather quickly.
>
> - Bernd
>
> -----Original Message-----
> From: Steve Preston [mailto:steveophonic@yahoo.com]
> Sent: Saturday, July 21, 2007 8:57 AM
> To: dakota-truck@dakota-truck.net
> Subject: Re: DML: RE: Checking transmission line
> pressure
>
>
> Thanks for the reply,Bernd!
>
> I don't have anything to read any transmission
> sensors
> with. My Elmscan 5 will do the engine sensors
> (only,apparently). About all I can do is measure
> actual fluid pressure with a gauge and look at my
> speedometer.
>
> I'm a little concerned that I can't find anyone on
> the
> internet that has had either the sensor or the
> solenoid cause erratic surging and intermittent
> performance. All I can find is complaints of second
> gear starts and failure to upshift. Maybe I need to
> verify that the fuel system and the engine vacuum is
> not causing anything before I blame the transmission
> for causing that one symptom for sure.
>
> Steve P.
>
>
>
>
>
> --- "Bernd D. Ratsch" <bernd@dodgetrucks.org> wrote:
>
> >
> > You can look at the pulse-width of the sensor and
> > line pressure. If the
> > sensor isn't showing 1psi per mph from 0-30mph,
> it's
> > bad (very common
> > problem). As for using the HVAC gauge, I wouldn't
> > run ATF through that
> > gauge. You can use a fuel pressure gauge
> (0-100psi)
> > and use the line taps
> > on the side of the transmission.
> >
> > - Bernd
> >
> > -----Original Message-----
> > From: Steve Preston
> [mailto:steveophonic@yahoo.com]
> > Sent: Friday, July 20, 2007 8:37 PM
> > To: dakota-truck@dakota-truck.net
> > Subject: DML: Checking transmission line pressure
> >
> >
> > Sup!
> >
> > I need to determine which is bad: the governor
> > pressure sensor,or the solenoid. I'd hate to spend
> > the
> > considerable sum for a part that I don't need,if
> > only
> > one of them is bad. I've read that if the line
> > pressure doesn't equate to 1 psi per mph as I
> > drive,the transducer is bad,and if the pressure is
> > right,the sensor is causing the problem. This is
> on
> > my
> > work truck (2003 3.9 CC 42RE)
> > that runs crappy (feels like engine miss and
> doesn't
> > want to upshift unless I back off the gas.) I
> spent
> > this afternoon checking the ignition system,and
> I'm
> > fairly sure the engine isn't causing it.
> >
> > First off,what's a wet gauge? I assume it measures
> > transmission fluid pressure? Does anyone know if
> an
> > HVAC suction side pressure gauge would work?
> >
> > I want to do some actual troubleshooting and track
> > this problem down. Unfortunately,my scanner
> doesn't
> > do
> > anything but engine sensors,and I haven't been
> able
> > to
> > find anything wrong there.
> >
> > Thanks,
> >
> > Steve P.
> >
> >
> >
> >
>
____________________________________________________________________________
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>
>
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This archive was generated by hypermail 2b29 : Wed Aug 01 2007 - 00:15:21 EDT