[xj40] For a little bit, running bad after start up

XJ40
1

Ok, I’ll give this a go. For quite a while my car has had this
symptom.

Car starts fine. If it sits for several days it will almost
immediatly start.

I live at the bottom of a 1/4 mile hill. When I start my car, go
to the end of my driveway (90 feet), start up the hill, my car
seems like it is going to die. If I leave off on the pedal, press
again it gets better, leave off again, press the pedal and it is
better or put the metal to the floor and it will pick up and go.
Usually about 1/2 way up the hill everything is fine. Last night I
used the pedal to the metal and think I heard a back fire. Not
sure because A/C was on full with the radio playing?

It idles fine and after the car gets over its little fit, verything
seems fine.

It can show the same problems on a flat area, such as, after being
in a store, starting the car and leaving a parking lot, could
produce the same problem.

Fuel pressure regulator was replaced in 2001 and now has 40,000
miles on it. Using a gauge the Vac holds well so I don’t think I
have any leaky vac hoses.

I have theorized the evaporative control system, such as the
cannister is allowing a rich condition.

I have theorized that maybe I am getting cavitation (Sp?) on the
fuel lines but doubt it because it would do it all the time.

Fuel pump age is unknown.
O2 Sensor is 1 year old.
Plugs and wires are good.

Fuel pump relay maybe? I’ve never been able to find mine. It is
supposed to be behind the knee bolster but I’ve never found it.

Any ideas.

John
90 XJ40–
John S
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2

Does it only do this with a cool or cold engine?
Do you have error codes on the VCM? I would almost suspect that its not
seeing the correct ambiant temperature and failing to enrich the mixture
during cold/cool starts. Could be such things as air charge temperature
sensor. Those usually set error codes though.----- Original Message -----
From: “John S” js4453@att.net
To: xj40@jag-lovers.org
Sent: Tuesday, August 08, 2006 6:54 AM
Subject: [xj40] For a little bit, running bad after start up

Ok, I’ll give this a go. For quite a while my car has had this
symptom.

Car starts fine. If it sits for several days it will almost
immediatly start.

I live at the bottom of a 1/4 mile hill. When I start my car, go
to the end of my driveway (90 feet), start up the hill, my car
seems like it is going to die. If I leave off on the pedal, press
again it gets better, leave off again, press the pedal and it is
better or put the metal to the floor and it will pick up and go.
Usually about 1/2 way up the hill everything is fine. Last night I
used the pedal to the metal and think I heard a back fire. Not
sure because A/C was on full with the radio playing?

It idles fine and after the car gets over its little fit, verything
seems fine.

It can show the same problems on a flat area, such as, after being
in a store, starting the car and leaving a parking lot, could
produce the same problem.

Fuel pressure regulator was replaced in 2001 and now has 40,000
miles on it. Using a gauge the Vac holds well so I don’t think I
have any leaky vac hoses.

I have theorized the evaporative control system, such as the
cannister is allowing a rich condition.

I have theorized that maybe I am getting cavitation (Sp?) on the
fuel lines but doubt it because it would do it all the time.

Fuel pump age is unknown.
O2 Sensor is 1 year old.
Plugs and wires are good.

Fuel pump relay maybe? I’ve never been able to find mine. It is
supposed to be behind the knee bolster but I’ve never found it.

Any ideas.

John
90 XJ40

John S
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3

In reply to a message from Dave sent Tue 8 Aug 2006:

No error codes, does it in hot or cold weather and are reasons why
it has been difficult to diagnose. It doesn’t do it every time

For a year (maybe two) this has been an ongoing habit. There has
been an occasion or two that the car stalled but started fine.

Intake temp sensor - 45,000 miles on it
Temp coolant sensor - 15,000 miles on it

I just did a test. After sitting all night, I started the car,
allowed it to come up to running temp, not hitting one pedal, got
in the car, headed up the hill and no problem. I did the test to
refresh my memory because I was thinking I had previously did sch a
test.

It seems to be when I jump in, fire it up and take immediately off.

Another test:

Sat here eating my cereal and then went out, started the car. Temp
is at normal and took off as I normally do. Going up the hill I
felt some of the on and off hesitation.

Hm?

Took the dog out, allowed car to sit for a few.

Next test:

I removed the valve (white/black)/ one side reads Dist. the other
Carb. I sprayed some lubricant into it, perhaps it was dirty and
sticking (often had that problem on the SIII). Again did the hill
test and no hesitation. This could be a false / positive result
and I’ll try again later. The valve looks like it would be
associated with an SIII timing advance set-up but I don’t think the
XJ40 has such an arrangement. Plus with its location and
orientation, it looks like it goes down toward the charcoal
cannister.

John
90 XJ40–
The original message included these comments:

Does it only do this with a cool or cold engine?
Do you have error codes on the VCM? I would almost suspect that its not

–
John S
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4

I wasn’t thinking so much as outside temperature but the engine temperature itself. For instance is it worse after sitting for several hours. Does it do it if you shut down a hot engine for only a few minutes?

From: “John S” js4453@att.net
Date: 2006/08/08 Tue AM 08:11:09 EST
To: xj40@jag-lovers.org
Subject: Re: [xj40] For a little bit, running bad after start up

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5

In reply to a message from dboarder@sympatico.ca sent Tue 8 Aug 2006:

By hot do you mean after a long run? It really doesn’t seem to
care if it has been running all day or the first start of the day.
Not worse or better after sitting several hours.–
The original message included these comments:

I wasn’t thinking so much as outside temperature but the engine temperature itself. For instance is it worse after sitting for several hours. Does it do it if you shut down a hot engine for only a few minutes?

–
John S
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6

In reply to a message from John S sent Tue 8 Aug 2006:

The pressing on the gas pedal causing improvement tells me that you
might have a gunky throttle body and idle stepper motor. This will
set no code but can sure cause driveability problems. The increased
airflow from opening the throttle is allowing the sticking
components to move to their correct positions. I always suspect
this problem with cold driveabilty troubles. Another suspect is a
boogered sticking EGR valve that is letting exhaust into the intake
at the wrong time, creating a moving vacuum leak.–
Brian Caro 96XJ6 4.0 63E-TypeS1FHC
Newport News, VA, United States
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7

In reply to a message from John S sent Tue 8 Aug 2006:

Have you checked the fuel pump pressure? When was the last time you
checked the fuel filter? If all else fails check the fuel screen in
the gas tank.
Crep–
crep
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8

In reply to a message from Brian Caro sent Tue 8 Aug 2006:

The EGR body is fairly new.

Throttle body removal and cleaning is on my list (2 years since
last removal.

Stepper motor was removed and cleaned.

It really isn’t a clod drive problem because it happens on a cold
and hot engine.–
The original message included these comments:

might have a gunky throttle body and idle stepper motor. This will
set no code but can sure cause driveability problems. The increased
boogered sticking EGR valve that is letting exhaust into the intake

–
John S
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9

In reply to a message from crep sent Wed 9 Aug 2006:

Fuel filter is one year old but it was doing this silly stuff
before the recent filter installation.

Haven’t checked the pump pressure (no gauge for it) but I can say
that it idles fine and goes like a bat out of ‘‘H’’ if you floor it.

I have been running it through my mind that there could be
something in the gas tank except, once the car clears its
problem…I am good to go.

IF only when it does this it would throw a code. Then I could hunt
down the problem.

This is the time the OBD II would come in handy because that does a
lot more diagnostic that OBD I. We have a DeVille that has the OBD
II system, I can run in depth checks that will appear on the
dashboard.

John
90 XJ40–
The original message included these comments:

Have you checked the fuel pump pressure? When was the last time you
checked the fuel filter? If all else fails check the fuel screen in

–
John S
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10

In reply to a message from John S sent Wed 9 Aug 2006:

Hello John
clean and set the butterfly/intake area and then make sure the TPS
volts are adjusted properly. after that the temp sensor
replacement. At least you will be starting from a level playing
field. steve–
stevec 92 XJ40 4.0 Daimler 103,000mls
chelmsford, United Kingdom
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