[xj] Series III Cold running problem

Has anyone experienced this problem in their XJ’s?

The car starts easily enough (even though the cold-start injector
doesn’t work) and will pull away o.k. first up.

Once the temperature needle starts to move though, the car will
miss-fire when you try to move off after a stop (in Brisbane
morning traffic, there’s lots of those). Sometimes the engine will
catch after a couple of seconds, othertimes it will stall
altogether. Just wonderful in traffic, the following drivers are
so patient as you try to get the thing started - not! The symptom
gets worse as normal running temperature is approached but once
fully warmed up, the symptom suddenly disappears and all is well
again.

I have replaced the extra air valve, but this made no difference.
This car does not overheat, even in heavy traffic in the Brisbane
summer, where temperatures well over 30C are routine. Normal gauge
reading is 95C, where the green starts. She’s just a b**** until
she gets warmed up.

Any suggestions (maybe don’t take it out in traffic)?

Thanks–
Hooksie
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–

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I wonder if your coolant temp sensor has a dead spot and is giving skewed
readings?

Doug Dwyer
Longview, Washington USA
1987 Ser III XJ6
1988 XJS V12From: “Hooksie” matyeo@optushome.com.au

The symptom
gets worse as normal running temperature is approached but once
fully warmed up, the symptom suddenly disappears and all is well
again.

===================================================
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Your problem is the coolant temperature sender, easily replaced. It is
on the coolant rail. When faulty, it tells the ECU that the engine is
fully warmed when it is not. The result is insufficient fueling,
stumbling, even stalling. Once the engine reaches about 70 to 75 degrees
the problem is resolved.

Gregory-----Original Message-----
From: owner-xj@jag-lovers.org [mailto:owner-xj@jag-lovers.org] On Behalf
Of Hooksie
Sent: December 27, 2005 3:20 AM
To: xj@jag-lovers.org
Subject: [xj] Series III Cold running problem

Has anyone experienced this problem in their XJ’s?

The car starts easily enough (even though the cold-start injector
doesn’t work) and will pull away o.k. first up.

Once the temperature needle starts to move though, the car will
miss-fire when you try to move off after a stop (in Brisbane
morning traffic, there’s lots of those). Sometimes the engine will
catch after a couple of seconds, othertimes it will stall
altogether. Just wonderful in traffic, the following drivers are
so patient as you try to get the thing started - not! The symptom
gets worse as normal running temperature is approached but once
fully warmed up, the symptom suddenly disappears and all is well
again.

===================================================
The archives and FAQ will answer many queries on the XJ series…
FAQs: http://www.jag-lovers.org/xjlovers/xjfaq/index.html
Archives: http://www.jag-lovers.org/lists/search.html

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// please trim quoted text to context only

In reply to a message from Dr. Gregory Andrachuk sent Tue 27 Dec 2005:

One note, and I experienced this. Some of the temp senders
do read a touch low, about 85’ish as opposed to 90. I
verified this via a resistance reading off the CTS after the
engine had been run hard and got nice and hot.

Apparently there are some differences in the temp senders
manufactured, and I did hear this elsewhere. 5 degrees
isnt that big a deal anyway, just as long as you are sure
your thermsostat is good, and the CTS also.–
Dave Williamson 85 XJ6 VDP ‘Black Beauty’
Lansdale, PA, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php

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The archives and FAQ will answer many queries on the XJ series…
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Dave:
I think we may have a confusion here, if I understand you correctly. I
am not talking about the transmitter to the dashboard gauge; I am
talking about the transmitter to the ECU. The indicator on the dash is
just that, an indicator, and a faulty reading there will not affect the
running of the engine.
Gregory-----Original Message-----
From: owner-xj@jag-lovers.org [mailto:owner-xj@jag-lovers.org] On Behalf
Of 1985vdp
Sent: December 27, 2005 8:54 AM
To: xj@jag-lovers.org
Subject: RE: [xj] Series III Cold running problem

In reply to a message from Dr. Gregory Andrachuk sent Tue 27 Dec 2005:

One note, and I experienced this. Some of the temp senders
do read a touch low, about 85’ish as opposed to 90. I
verified this via a resistance reading off the CTS after the
engine had been run hard and got nice and hot.

Apparently there are some differences in the temp senders
manufactured, and I did hear this elsewhere. 5 degrees
isnt that big a deal anyway, just as long as you are sure
your thermsostat is good, and the CTS also.

===================================================
The archives and FAQ will answer many queries on the XJ series…
FAQs: http://www.jag-lovers.org/xjlovers/xjfaq/index.html
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In reply to a message from Dr. Gregory Andrachuk sent Tue 27 Dec 2005:

As I said to Gregory, my mistake. I am but a greenhorn in
the maintenance of Jags.–
Dave Williamson 85 XJ6 VDP ‘Black Beauty’
Lansdale, PA, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php

===================================================
The archives and FAQ will answer many queries on the XJ series…
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In reply to a message from Dr. Gregory Andrachuk sent Tue 27 Dec 2005:

Just curious, but what is the recommended maintenance of the
CTS sensor? How often should it be checked?–
82 Series III XJ6 143k+
Berkeley, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php

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Other then checking the connector/terminals for security and cleanliness
every few years, no maintenance, just check it when you suspect it is
causing a problem.

Doug Dwyer
Longview, Washington USA
1987 Ser III XJ6
1988 XJS V12From: “Ryan A.” rxm6@hotmail.com

Just curious, but what is the recommended maintenance of the
CTS sensor? How often should it be checked?

===================================================
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In my experience, the SIII’s sensor at the rear of the water rail, that turns
on the purge and airpump valves when cold needs more checking. Of course,
it’s less critical than the CTS.–
Alex
79xj6L SII (BRG + wires)
86xj6 SIII (Black)
61 Sprite MkII (Red)
Menlo Park, Calif.

Doug Dwyer wrote:

Other then checking the connector/terminals for security and cleanliness
every few years, no maintenance, just check it when you suspect it is
causing a problem.

===================================================
The archives and FAQ will answer many queries on the XJ series…
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There is no maintenance of this sensor, and it does not need period
checking. You will know when it is not working.
Gregory-----Original Message-----
From: owner-xj@jag-lovers.org [mailto:owner-xj@jag-lovers.org] On Behalf
Of Ryan A.
Sent: December 27, 2005 7:17 PM
To: xj@jag-lovers.org
Subject: RE: [xj] Series III Cold running problem

In reply to a message from Dr. Gregory Andrachuk sent Tue 27 Dec 2005:

Just curious, but what is the recommended maintenance of the
CTS sensor? How often should it be checked?

82 Series III XJ6 143k+

===================================================
The archives and FAQ will answer many queries on the XJ series…
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It’s been two years since we unconfused this issue, Gregory; the Coolant
Temp Sensor goes to the ECU - the temp transmitter goes to the gauge…:slight_smile:

We sing as one on the reality though…:slight_smile:

Frank
xj6 85 Sov Europe (UK/NZ)

Dr. Gregory Andrachuk wrote:>Dave:

I think we may have a confusion here, if I understand you correctly. I
am not talking about the transmitter to the dashboard gauge; I am
talking about the transmitter to the ECU. The indicator on the dash is
just that, an indicator, and a faulty reading there will not affect the
running of the engine.
Gregory

In reply to a message from Dr. Gregory Andrachuk sent Tue 27 Dec 2005, Dave wrote;

One note, and I experienced this. Some of the temp senders
do read a touch low, about 85’ish as opposed to 90. I
verified this via a resistance reading off the CTS after the
engine had been run hard and got nice and hot.

Apparently there are some differences in the temp senders
manufactured, and I did hear this elsewhere. 5 degrees
isnt that big a deal anyway, just as long as you are sure
your thermsostat is good, and the CTS also.

===================================================
The archives and FAQ will answer many queries on the XJ series…
FAQs: http://www.jag-lovers.org/xjlovers/xjfaq/index.html
Archives: http://www.jag-lovers.org/lists/search.html

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Yes, Frank; I know.
Gregory-----Original Message-----
From: owner-xj@jag-lovers.org [mailto:owner-xj@jag-lovers.org] On Behalf
Of Frank Andersen
Sent: December 27, 2005 10:04 PM
To: xj@jag-lovers.org
Subject: Re: [xj] Series III Cold running problem

It’s been two years since we unconfused this issue, Gregory; the Coolant

Temp Sensor goes to the ECU - the temp transmitter goes to the
gauge…:slight_smile:

===================================================
The archives and FAQ will answer many queries on the XJ series…
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Dr. Gregory Andrachuk wrote:

Yes, Frank; I know.

Ha, Gregory, I know you do and I know you know I know you do…:slight_smile:

Frank
xj6 85 Sov Europe (UK/NZ)

It’s been two years since we unconfused this issue, Gregory; the Coolant

Temp Sensor goes to the ECU - the temp transmitter goes to the
gauge…:slight_smile:

Frank===================================================
The archives and FAQ will answer many queries on the XJ series…
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In reply to a message from Ryan A. sent Wed 28 Dec 2005:

Check and toss :slight_smile:

Only $7-$20 part, depending on what you buy :slight_smile:

I bought the $12 one, works perfectly fine. I’m sure its
just a bimetal thermostatic device.–
The original message included these comments:

Just curious, but what is the recommended maintenance of the
CTS sensor? How often should it be checked?


Dave Williamson 85 XJ6 VDP ‘Black Beauty’
Lansdale, PA, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php

===================================================
The archives and FAQ will answer many queries on the XJ series…
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Hello gents,

Resurrecting this thread as I’m experiencing roughness/lack of power and rpm’s/black smoke that goes away as engine warms up. Is it still the consensus to look at the Coolant temperature sensor first or do you have anything else to suggest?
One trick on the XJS I had to check the CTS was to bypass it with a paperclip, for example. Is there such a trick with the xj6 sensor? Thanks!! 1985 XJ6

**
Question, Francois…

Does misfiring/smoke/lack of power only occur when you accelerate with engine cold? In which case; search for ‘capmod’ or ‘Cold start EFI overfuelling’ in Archives…

The cause is arcing in the AFM - completely cured by adding a capacitor across two wires; an authorised Jaguar bulletin remedy. However, there is no specific test apart from the very characteristic symptoms described…

Frank
xj6 85 Sov Europe (UK/NZ)
**

Hi Frank,

Thanks for the reply and suggestion. It started about a month ago. Engine has no to little power to move the car at all when cold. Flat surfaces are ok but as soon as an incline s there, forget it. What I do now is I pull over on the side of the road and idle until temp warms up, tapping the throttle from time to time to see how engine revs. Then all of a sudden all is well and it s like nothing happened.

(car stopped, engine running, transmission in neutral, RPM would go to 3000 max and black smoke is observed)

Francois,

Please use the link below to go to the old Jag-Lovers site for their Frequently Asked Question (FAQ) page. Once there, you will find dozens of FAQ write-ups with helpful information about many of the problems commonly encountered with our XJ6s and XJ12s. Look under the “Fuel System (Fuel Injection)” section for “Black Smoke and Backfire When Cold (Capacitor Mod)” and see if this helps. Jaguar issued a Technical Service Bulletin years ago about this problem along with the fix. Based on your posts I believe that this information in the FAQs is what you need to fix your problem.

http://www.jag-lovers.org/xjlovers/xjfaq/index.html

I have been a member of Jag-Lovers for almost 20 years and it seems to me that very few new problems occur and often the solutions to problems being posted about are found in the FAQs and archives. I use the FAQs and archives regularly as I work on my five Jaguars and find them a very efficient way to address many of the issues that I have encountered. I hope you find the FAQs helpful for this issue and possibly others that you may not have posted about.

Paul

1 Like

Thanks Paul, i usually do a search first before asking something that had been answered many times before nothing really came up besides this thread. I was not aware of that FAQ section but I am now thanks to you!

Couldn’t the switch that activates the cold start injector be somewhat sticky?
As soon as it runs, pull the blue connector that is on the plenum of the intake. This disables the injector if it was still dumping fuel.
It’s too rich. Simple things first.

David