Ignition timing in Caravan '93 - 3.0L engine

Dodge Caravan - 1993 SE
Miles: 87K
Engine : Mitsubishi 3.0L

The book says to check the ignition timing, you should disconnect the
coolant sensor. As soon as I disconnect the coolant sensor the engine starts
breathing a lot making and the timing mark keeps jumping between 10-15
degrees. If the sensor is connected it doesn't breath at all and the engine
seems to run normally. What could I be missing here?

TIA
-Paul

 

Does the cooling fan turn on when you disconnect the coolant
sensor?

 

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You are supposed to disconnect the coolant sensor and yes the radiator fan
will turn on. If you set the timing and reconnect the coolant sensor,
restart the car ......if it runs bad then you have a problem. The mark can
also be jumping around because the belt is loose.

Glenn Beasley
Chrysler Tech

 

aarcuda69062,
Yes, the cooling fan does turn on and that is when the engine starts
breathing i.e. RPM goes low and then perhaps IAC tries to maintain the RPM
and this process keeps repeating while the coolant sensor is disconnected.

-Paul

 

Glenn,
Thanks for the response. Yup the fan does turn on after I disconnect the
sensor. The van seems to run fine after I connect the sensor back. I was
expecting the engine to run steadily so that I can see a steady timing mark
to ensure that it is indeed 12 degrees +/- 2. By belt being loose, are you
talking about the timing belt ? If indeed it is the timing belt causing it,
then I wonder why it does not happen when sensor is connected back.

-Paul

 

--

When the sensor is connected, the timing is controlled by the engine
controller, by disconnecting the sensor the timing is not being controlled
and the mark should be steady unless the belt is loose or the distributor
is worn. how many miles on this and has the belt changed?

Glenn Beasley
Chrysler Tech

 

It has around 87K miles and the timing belt has never been changed.
Distributor, rotor, sparkplugs and the wires are all new and I bought from
chrysler. I am the first owner of this vehicle. This is what triggered me to
check the ignition timing.

-Paul

 

Just checking that you were disconnecting the right thing.