[xj-s] 96 4.0 XJS Hard to Start anytime!

XJ-S
1

This car is hard to start hot or cold… has DTC P0340
camshaft position sensor circuit malfunction. I have
monitored the operational data on the engine, the timing is
advancing properly. But the airflow meter is at 0.00 at idle
and only increases to 0.04 when throttle is opened when
running.The spark plugs are black & sooty indicating rich
fuel mixture.The O2 sensors are fluctuating properly,
coolant temp is ok throttle position ok. I cant properly
check fuel pressure running but with ignition on it has 60+
after the regulator.’‘not running’’.Any suggestions on these
circumstances?? Help is greatly appreciated. Thank You!!!
@travo–
travo
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2

Travo,

The P0340 code is for the Camshaft Position Sensor.
That thingy that replaced the distributor.

The reason your car is hard to start is; with no
reference to cylinder #1 the ECU shifts the firing
order by one cylinder until the engine starts. This
takes a few revolutions per shift until the engine
starts. Crank, crank, crank, shift firing order,
crank, crank, crank, shift firing order, crank, crank,
crank, start! If only you could stop the engine with
#1 as the next cylinder to fire you would not have a
problem.

Repair from the service manual:

Check harness for good connections.
Check for alignment by rotating the engine to #1 and
see if the Camshaft Position Sensor (CMP) mark is
under the sight glass.
Check for driven gear tooth damage.
Replace the CMP with a known good one.
Check harness for good connections.

You seem to also have a coolant temp sensor problem
with the black plug issue. A new temp sensor should
be tried… however with two sensors going out I
would think harness connector issues.

Have you had the car detailed or engine cleaned? Has
a coolant hose leaked coolant on the front of the
engine?

The small FI type terminals are known to corrode and
not make good contact. I do not know a good way to
clean them.— travo travweather@yahoo.com wrote:

This car is hard to start hot or cold… has DTC
P0340
camshaft position sensor circuit malfunction.

Geoff Green

96 XJ6 X300, 95 XJS 4.0 conv, 76 XJ-S, 61 E-type OTS

Keeping track of every Jaguar XJ-S, with your help.
http://www.xjsdata.com

3.6 XJS Register paulzimmer@btopenworld.com

Eventer Register pascal.mathieu@perso.be

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3

In reply to a message from Geoffrey Green sent Sun 23 Sep 2007:

o.k. I have checked the connections they seem o.k. I havent
had it cleaned or had any leaks. The coolant temp sensor
shows to be working according to my scan tool.But the
Airflow meter is only reading 0.00 at idle & only increases
to 0.04 when reved up no matter how far I rev it, according
to the scan tool, could the airflow meter be why the plugs
are black??–
travo
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4

travo,

the pins on the MAFS and voltage are:

001 12V Ignition dependent voltage supply.
002 0-5V Signal- low current
003 0V ground via ECU

pin 002 to ground 200K ohms

Nominal Flow
Output (kg/s)
Voltage

0.813 0.002
0.982 0.003
1.117 0.004
1.555 0.009
1.927 0.016
2.344 0.028
2.751 0.045
3.103 0.065
3.451 0.090
3.867 0.125
4.305 0.170
4.700 0.220

If you are measuring a low voltage at the MAFS the
signal to the ECU will be that you are running low air
volume and the car will be showing lean on the plugs
not rich.

Is your voltage meter set at the correct decimal point
value? Check the other sensors as your low reading
may be affecting other sensor inputs to the ECU.

I thought my coil connections were good however I was
incorrect and after replacing the connectors the
engine ran better than ever. Tight connections do not
mean good electricity flow.— travo travweather@yahoo.com wrote:

In reply to a message from Geoffrey Green sent Sun
23 Sep 2007:

o.k. I have checked the connections they seem o.k. I
havent
had it cleaned or had any leaks. The coolant temp
sensor
shows to be working according to my scan tool.But
the
Airflow meter is only reading 0.00 at idle & only
increases
to 0.04 when reved up no matter how far I rev it,
according
to the scan tool, could the airflow meter be why the
plugs
are black??

Geoff Green

96 XJ6 X300, 95 XJS 4.0 conv, 76 XJ-S, 61 E-type OTS

Keeping track of every Jaguar XJ-S, with your help.
http://www.xjsdata.com

3.6 XJS Register paulzimmer@btopenworld.com

Eventer Register pascal.mathieu@perso.be

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5

In reply to a message from Geoffrey Green sent Mon 24 Sep 2007:

The voltage at the Airflow Meter is what you said I have
already checked that. And the 0.00 and 0.04 is info from my
scan tool, It’s reading is in Lbs/min. As far as the coil
connectors should one have 12v and other ground? or
reference? also I can clear the cam position code & as long
as I don’t drive it and just start it an run it in driveway
the engine light stays off, but as soon as I go 5 miles down
the road and cut it off then start it back it’s on. It
doesn’t come on going down road only after I cut it off.
Why?? Thank You for your help. I’m sorry I’m such a bother.
Thanks again…–
The original message included these comments:

the pins on the MAFS and voltage are:
001 12V Ignition dependent voltage supply.
002 0-5V Signal- low current
003 0V ground via ECU
pin 002 to ground 200K ohms
Nominal Flow

–
travo
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6

The voltage at the Airflow Meter is what you said I
have
already checked that.

Good.

And the 0.00 and 0.04 is info
from my
scan tool, It’s reading is in Lbs/min.

I cannot convert the voltage to correspond to Lbs/min.
The manual gives only kg/sec

As far as
the coil
connectors should one have 12v and other ground? &
or > reference?

I was measuring AC voltage across the coil with the
engine running. As the engine warmed up the voltage
dropped and the coil stopped working at a low voltage.
But you do not have this code so do not worry about
coils. I was only using this as an example of tight
connections that gave poor electrical flow.

also I can clear the cam position code
as long
as I don’t drive it and just start it an run it in
driveway
the engine light stays off, but as soon as I go 5
miles down
the road and cut it off then start it back it’s on.

That’s good because you still have a problem with the
ECU not receiving a signal from the Cam Position
Sensor.

It
doesn’t come on going down road only after I cut it
off.
Why??

Because some codes are set after a second or third
showing of an error. Some are set after failure of a
test. Some are set as soon as the problem occurs.

Thank You for your help. I’m sorry I’m such a
bother.
Thanks again…

You are welcome and it’s only a little bother for me.
It’s a big bother for you.

You must fix the first error code problem first. Then
worry about other issues. Focus on the Camshaft
Position Sensor for now. Have you looked at the
position when at TDC for cylinder #1?

Geoff Green

96 XJ6 X300, 95 XJS 4.0 conv, 76 XJ-S, 61 E-type OTS

Keeping track of every Jaguar XJ-S, with your help.
http://www.xjsdata.com

3.6 XJS Register paulzimmer@btopenworld.com

Eventer Register pascal.mathieu@perso.be

// please trim quoted text to context only— travo travweather@yahoo.com wrote:

7

In reply to a message from Geoffrey Green sent Mon 24 Sep 2007:

Thanks. I did check the position of TDC ans Cam sensor If it
is off it’s not by much, I mean it lined up as close as I
could get it without TDC indicator that screws in head. It
does look like someone has had the cam sensor out before me
because the bolt holding it down is not on the original
screw mark from factory just a little to the left off it,
just a hair. And as far as the Airflow Meter The other
American cars such as my 87 GTA Trans Am when you rev it up
it goes almost to 5.00 lbs and runs at 1.?? lbs/min idling
so I was thinking this Jag should run close to the same. If
it will help you I can e-mail the data sheets I got from my
scan tool.I will check the voltage like you described though
with my ohm meter. I should use the 20 volt setting right?
For the Air flow Meter?–
travo
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8

In reply to a message from travo sent Mon 24 Sep 2007:

On the cam position sensor, close is good enough. It does not work
like a distributor. It handles only a signal to the ecu
indicating cam timing. You will be correct or out by 180 Degrees.
If you are real anal about it, simply line up the circle on the
rotating disc with the mark in the window at TDC.–
The original message included these comments:

Thanks. I did check the position of TDC ans Cam sensor If it
is off it’s not by much, I mean it lined up as close as I
could get it without TDC indicator that screws in head. It
does look like someone has had the cam sensor out before me
because the bolt holding it down is not on the original
screw mark from factory just a little to the left off it,
just a hair. And as far as the Airflow Meter The other

–
uncle
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9

In reply to a message from uncle sent Mon 24 Sep 2007:

Yes thats what I thought.But does any one know why its
burning rich if the Airflow Meter is showing low air flow??
And the coolant sensor is working I can watch it from
start-up to running temp on my scan tool.–
travo
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10

In reply to a message from travo sent Mon 24 Sep 2007:

I had a similar peoblem with an AJ6 engine. It was the temp
(Multiple wire) sender for the ECU, not the one (single wire)for
the gauge. The AJ16 engine has similar circuitry. Are you
checking the correct sendor?–
The original message included these comments:

Yes thats what I thought.But does any one know why its
burning rich if the Airflow Meter is showing low air flow??
And the coolant sensor is working I can watch it from
start-up to running temp on my scan tool.

–
uncle
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11

In reply to a message from uncle sent Mon 24 Sep 2007:

Yes I just rechecked the temp sensor the 2 wire sensor as
the engine got warmer the resistance showed actually better
than the specifications I have on it.According to temp
resistance.
But I checked the plug at the cam sensor and the voltage
was 12.81 on the + 11.41 on the o 0.00 on the ground
with the plug unplugged and the switch on. when I plugged it
up and started it it went up to 13.41 on the + 14.11 on
the o and 0.00 on the ground is this how this should work??–
travo
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12

In reply to a message from travo sent Mon 24 Sep 2007:

I do not know the correct voltage speccs., Sorry.–
The original message included these comments:

But I checked the plug at the cam sensor and the voltage
was 12.81 on the + 11.41 on the o 0.00 on the ground
with the plug unplugged and the switch on. when I plugged it
up and started it it went up to 13.41 on the + 14.11 on
the o and 0.00 on the ground is this how this should work??

–
uncle
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13

In reply to a message from uncle sent Mon 24 Sep 2007:

OK thanks for your help.–
The original message included these comments:

I do not know the correct voltage speccs., Sorry.
uncle
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–
travo
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14

travo,

Where are you with your car?

I looked at the readouts you sent. 183 F is still a
bit cold it should be 203 F. I will check mine this
weekend.

I wonder what it means with your “Short Term Fuel
Trim2” being -2.0 on bank 1 and +6.0 on bank 2.

Have you any voltage readings from the different
sensors? Either sensor low voltage 0.0v to 5.0v or
supply 12.0V (may change depending on battery voltage)— travo travweather@yahoo.com wrote:

Yes thats what I thought.But does any one know why
its
burning rich if the Airflow Meter is showing low air
flow??
And the coolant sensor is working I can watch it
from
start-up to running temp on my scan tool.

Geoff Green

96 XJ6 X300, 95 XJS 4.0 conv, 76 XJ-S, 61 E-type OTS

Keeping track of every Jaguar XJ-S, with your help.
http://www.xjsdata.com

3.6 XJS Register paulzimmer@btopenworld.com

Eventer Register pascal.mathieu@perso.be

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15

In reply to a message from Geoffrey Green sent Fri 28 Sep 2007:

I’m in bristol tn. Do you think thermostat might be weak??
also?? so far all the sensors I’ve checked has had battery
voltage on supply & a ground, but the cam sensor has 11.81
on the terminal in the center marked with the o, unplugged
but when I plug it up and start it it the gets more voltage
than the supply wire!!! It then has what the altanator is
putting out and the supply wire has a little less!!! so far
the supply has been what the battery has had in it.most of
the vehicles nowa days has 5.0 volts on the signal/reference
wire, this is first car that I’ve run across thats had that
much 11.81 on the signal/reference wire. Oh and by the way I
changed my scan tool to metric and monitored the airflow
meter and it seems ok. that was my problem setup for kg’s
not lbs!!! I also checked it with dvm and matched my scan
tool readings. So that rules that out, I think I’ll try a
new temp sensor & thermostat. Oh one other thing I’ve had
the car 3 years, not long after I had it I was going down
the road and all of a sudden boom, black smoke all be hind
me!!! but hasn’t done it since. And the hard start problem
didn’t start until about 4 months ago, the check engine
light has only been on about 3 weeks. sound a bit odd to you???–
The original message included these comments:

I looked at the readouts you sent. 183 F is still a
Have you any voltage readings from the different
sensors? Either sensor low voltage 0.0v to 5.0v or
supply 12.0V (may change depending on battery voltage)

–
travo
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