I have been chasing this rough idle problem for some time now. I have
replaced a lot of stuff (IAC, MAP, intake air sensor, and tested the
TPS). I was reading the Haynes manual and it says the water temp
sensor is connected to the fuel injector system some how. Can this
cause an idle problem?
Engine temp is used as a base line to set mixutre (that and MAP
sensor at startup determining pressure altitude) so it is conceivable
that it could effect idle but it would likely have running problems
Yes it can....but...
When a coolant temp sensor give an incorrect reading it causes the fuel mix
to be either too rich or too lean. If your oxygen sensors are working
correctly they will sence the rich/lean mix and the pcm will compensate for
it. You would probably not notice this when driving the vehical. What you
would notice is the idle speed may be too high or too low as this is the
sensor the pcm looks at to set idle speed. Depending on how new your vehical
is the pcm could still give a fairly correct idle speed by looking at other
sensors and/or calculating run time.
It looks like it's time to get a scanner on it instead of throwing parts at
it. It may save you some money in the long run.
Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here.
All logos and trade names are the property of their respective owners.