Jay & Dana wrote:
>
> Hey Biff,
>
> I just found out that I dont have one ( EGR valve ) on my Dak but I also
> never knew that the 02 sensors will affect start-up and idle quality when
> the engine is cold. I guess I will have to brush up on this further.
>
> Thanks for your knowledge on this subject.
>
> - Jay
>
Unless someone shows me factory tech specs and details contradicting my
statements... to the best of my knowledge, an O2 sensor should not have
an effect on start up and cold idle.
You can pull that sensor right out and its not going to give you a hard
start condition. The sensors are internally heated to get them up to
operating temp faster, but I am under the impression that the ECM's do
not read from them (or use the input from them rather) until the engine
and O2 sensor are at normal operating temp. Until its up to temp they
*should* run off preprogrammed air/fuel ratios for a cold start situation.
An 02 sensor has an effect on the pulse width (length of time) that the
injector squirts fuel into the intake. If an O2 sensor isn't working
properly, it will *almost* always throw a code. Check engine lights
will be triggered for "internal heater/circuit inoperative" - meaning
the internal heater is not working - can either be a faulty wire or a
faulty sensor. OBD systems can set a code along the lines of "no change
in O2 sensor voltage" ... meaning the constantly changing signal
(voltage) that the sensor is supposed to send to the ECM, is not
changing... indicating possible sensor failure or a bad wire.
You'll see codes "sensor voltage high/low - for too long a time etc"
usually indicating a lean/rich issue - or a faulty sensor. More times
than not its a rich/lean condition - not a faulty sensor.
If the sensors are not working right - I can see where it might cause a
problem with drivability under load and normal operating temp conditions
- but more ofton than not - you'll see reduced fuel economy if an O2
sensor dies - because the ECM isnt using real time data for the air/fuel
ratios.
Do a test - unplug your O2 sensors from the wire harness and disconnect
them. See what happens :)
I would look at engine management and/or ignition/fuel problems before I
would suspect an O2 sensor problem, if there are no codes. Especially if
you are seeing the problem at a cold start only and not after the truck
has been running and has warmed up.
Two things people tend to blame first for engine problems are O2 sensors
and fuel filters. Not usually the problem...
-- ------------------------------------------------------------- Rocks are for skipping... I'm all about the mud 75 Honda CL360, 89 Dakota, 89 Dakota 4x4, 95 Dakota 4x4, 96 Neon, 01 Ram 4x4 http://members.aol.com/silvereightynine/ AIM & Yahoo: SilverEightynine. . .------------------------------------------------------------------. | Make your plans NOW to attend the National DML Meet in Colorado! | | Date: July 15-23, 2006 - More info: http://meet.dakota-truck.net | `------------------------------------------------------------------'
This archive was generated by hypermail 2b29 : Sun Apr 02 2006 - 18:27:15 EDT