[x300] x300 coolant temperature sensor misfires & stalling CURED

X300
1

After replacing three coils packs with cracks in with good used
ones plus a full set of spark plugs and still having stalling at
junctions, poor acceleration from cold missing whilst being revved
from stationary at about 4000rpm and one or two misfires each
jeorney from a cold start.

I removed the new spark plugs to notice they were slightly black
round the outside edges, Also my car ran OK on LPG but Rubbish on
petrol. So I searched the forums on here for possible causes and
purchased a new coolant sensor �8 + P&P plus a few other bits etc.

I recieved the new coolant sensor from britishparts today and
carried out the following tests prior to installing it, using a
multimeter to measure the resistance at different temperatures in
the comfort of my own kitchen!

New Temperature Sensor

Room temperature = 2800 ohms
Iced water = 5360 ohms
Boiling pan of Water = 195 ohms

Old Temperature Sensor

Room temperature = 2360 ohms
Iced water = 5330 ohms
Boiling pan of Water = 186 ohms

Notice how the old sensor nearly matched the minimum and maximum
values of the new sensor but at room temperature it was way off the
mark therefore I would conclude that the sensor is running out of
its designed range. Previous multimeter tests on the car had
confirmed it was working just not correctly it transpired.

I also observed the old sensor seemed slower to respond to
temperature changes but I have no accurate way of proveing this.

I fitted the new sensor and took the car out for test drive and I
haven’t had a misfire or stall since, the car has a smoother idle
when running on petrol but it was still smooth on LPG beforehand.

Also a few years ago I had the stalling at junctions on petrol no
misfires involved though, this was down to the car needing new
Lambda sensors as it failed the MOT on emmissions. Basically any
fuel mixture issue will cause your Jag to behave badly!

Thanks to all who take the time to contribute information on this
forum and share their knowledge and experiences.

Regards

Dave

1996 Jaguar x300 3.2 176K
1976 Rolls Royce Silver Shadow–
bigwheels18
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–

2

In reply to a message from bigwheels18 sent Mon 17 May 2010:

Thanks for your excellent analysis!You can simulate the
symptoms of a failing CTS by inserting a varistor.I posted
about this a few years ago.
Just be very sure you have the correct part number for the
coolant temperature sensor(CTS).There are several sensors
with very similar part numbers for Jags that have very
different values.Some have only a single letter difference
in the part number. British Parts was an excellent & clear
source when I worked on this issue 2 years ago.Other sites
were disturbingly vague. NAFYYY
For others thinking about doing this simple task, don’t buy
the coolant temperature sender/switch by mistake!–
The original message included these comments:

petrol. So I searched the forums on here for possible causes and
purchased a new coolant sensor �8 + P&P plus a few other bits etc.
I recieved the new coolant sensor from britishparts today and
carried out the following tests prior to installing it, using a
multimeter to measure the resistance at different temperatures in
the comfort of my own kitchen!
New Temperature Sensor
Room temperature = 2800 ohms
Iced water = 5360 ohms
Boiling pan of Water = 195 ohms
Old Temperature Sensor

–
95 XJR, 69 E-Type ots ,07 Miata ,‘X’-type SUV
Sierra Madre Ca 91024, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php –