engine stalling at idle

When I shift to neutral coming to an intersection or stop, my 4.0 FI
engine sometimes stalls out. It seems to have coincided with my
speedometer not working. Would that be a cause?


I disconnected the connector leading to the sensor/gear on the transfer
case and I noticed a three wire connection, so it must be
electronically sensed to the speedoemter. Before I purchase another
sensor is there anything I can ohm out or check for voltages on the
three wire connector? Diagram anyone has?


I also thought about the sensor gear not meshing, so if I disconnect
the sensor/gear from the transfer case with the cable connected, turn
key to ignuand manually torn the gear by hand, should I see an output
at the speedometer if the sensor is working?

waz

updawaz00 did pass the time by typing:
> When I shift to neutral coming to an intersection or stop, my 4.0 FI
> engine sometimes stalls out. It seems to have coincided with my
> speedometer not working. Would that be a cause?

I don't think a failed speedometer sensor would do that.

All sorts of causes including a bad engine ground strap, corroded harness
or connectors, broken wire, etc. But first, what is the year, and make
of your Jeep?

Certain models you can pull the engine codes with this procedure.
http://www.allpar.com/fix/codes.html

> I disconnected the connector leading to the sensor/gear on the transfer
> case and I noticed a three wire connection, so it must be
> electronically sensed to the speedoemter. Before I purchase another
> sensor is there anything I can ohm out or check for voltages on the
> three wire connector? Diagram anyone has?

That's where knowing the year and model will help us. Some years changed
color codes.

> I also thought about the sensor gear not meshing, so if I disconnect
> the sensor/gear from the transfer case with the cable connected, turn
> key to ignuand manually torn the gear by hand, should I see an output
> at the speedometer if the sensor is working?

Your not going to be able to turn it fast enough by hand to see anything.

--
-- DougW -- 93 ZJ 4.0 http://members.cox.net/wilsond
HESCO Supercharger - 300W IASCA Stereo - Edelbrock IAS Shocks
Gibson Exhaust - rear DCpower - custom gauge install - Stillen Rotors
Banks Header - and BEER, in the fridge!

If it is a TJ, then yes, the PCM does get input from the speed sensor
during deceleration. I would suspect the same in a Wrangler.

It is a magnetic hall effect sensor that generates 8 pulses per rotation
according to the TJ manual. It needs this to know if you are still
moving at closed throttle for a 'deceleration' injector mode or are
sitting at a still idle.

I 'think' the pulses are pin 1 and 2 with pin 3 the ground.

I don't have a clue about hand spinning the gear and seeing anything up
top, but that should show on a meter as voltage pulses....

The computer needs a stable TPS signal and the plugs and sockets on them
can need a clean once in a while, but that usually gives high revs on
first start with a stall at the first stop if dirty.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's

wrote:
>
> When I shift to neutral coming to an intersection or stop, my 4.0 FI
> engine sometimes stalls out. It seems to have coincided with my
> speedometer not working. Would that be a cause?
>
> I disconnected the connector leading to the sensor/gear on the transfer
> case and I noticed a three wire connection, so it must be
> electronically sensed to the speedoemter. Before I purchase another
> sensor is there anything I can ohm out or check for voltages on the
> three wire connector? Diagram anyone has?
>
> I also thought about the sensor gear not meshing, so if I disconnect
> the sensor/gear from the transfer case with the cable connected, turn
> key to ignuand manually torn the gear by hand, should I see an output
> at the speedometer if the sensor is working?
>
> waz

Doug, 1992 is the year. Make is YJ Wrangler.

Mike, It is a YJ, but it may be the same issue you are talking about. I
purchased a service shop manual ... should get here by wednesday. It
seems to be a gray issue on how to properly troubleshoot a sensor.
Somewhere I heard to measure 5 volts... but where and do I have to
pierce the insulation while the connector is connected is not
disclosed. Hope the shop manual is worth the $100!

Actually, if it is pulsed at 5 volts, I should be able to see it on one
of the wires as I'm turning the gear, I have an old scopemeter to
watch. Of course, I'm assuming the sensor does not have to be grounded
to the transfer case and my vehicle works like a TJ.

I'm betting the 3 pins are volts input, pulsed volts output, and
ground....

I

They could be 5 volt pulses. The sensor itself puts out the volt
pulse. They only happen when it is spinning so I think a bench test
might be in order?

Basically I would put the meter on pin 1 and 2 and hand spin it to see
if it pulses. Or 1 and 3 or 2 and 3. It is something like some of the
distributor units, they show a pulse on a meter when hand moved.

Mike

wrote:
>
> Mike, It is a YJ, but it may be the same issue you are talking about. I
> purchased a service shop manual ... should get here by wednesday. It
> seems to be a gray issue on how to properly troubleshoot a sensor.
> Somewhere I heard to measure 5 volts... but where and do I have to
> pierce the insulation while the connector is connected is not
> disclosed. Hope the shop manual is worth the $100!