[x300] 97 XJR problems.. Im STUMPED! help!

X300
21

In reply to a message from SpeedyPAL sent Fri 16 Feb 2007:

Pete,

This is an interesting idea… I did listen for leaks, but all
sounds good… Where do they normally crack, and I guess I have to
pull the heat shield to see them??

but if that is the prob, why would it run good at times, but mostly
bad?? and come and go on the same drive?? I once got abotu 20
minutes of HARD run time and it was flawless… then all of a sudden
im back to this… and sometimes its not too bad and if I ease into
the gas, or feather thru the misses, it will hook up and take off
like a rocket… Doesnt sound like a crack in the manifold, but
still worth looking into after I swap over the fuel regulator and
CPS…

Thanks!
Ron–
The original message included these comments:

They are very prone to cracking on the supercharged models.
The cracks apparently allow O2 to sneak into the exhaust where it
is seen by the O2 sensors. The ECU interprets this as a lean
mixture and richens the mixture.
I had a very similar problem last summer but mine would run great
for days and then stumble all over itself. The plugs were
definitely showing very rich when it was running poorly, and very
normal when running great. I welded the cracks in both manifolds
about 5,ooo miles ago. The problem has not come back, yet!
Good Luck, Pete

–
eyeinstine
North Hanover Twp/NJ, United States
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22

Is there a fuel pressure regulator on the car?

Has the fuel rail pressure been measured?

Please disregard this message if I don’t know what I am talking about.

XJRGUY

23

In reply to a message from eyeinstine sent Fri 16 Feb 2007:

Hi, the ECU is behind the plastic side panel in the driver’s
side footwell. There’s various other control modules dotted
around the car but that’s the engine ECU Brian’s talking
about. If it’s fitted the same as the N/A 4.0, the kick
panel is held in by a plastic fastner, the panel then
unclips and the ECU is mounted up the side. It’s held by 2 x
(10mm I think) bolts and then pull it out from the bottom
and drop it down gently - there’s a tab near the top which
hooks behind the panel.

To me it sounds like a wiring problem, the faults you’re
getting are too varied for a single problem. Ditto with
Brian about rf spikes from the battery connections upsetting
the ECU, think of how electrical equipment gets damaged by
thunder storms. Look for corrosion and any sign of water
ingress on the PCB or connectors. That’s where I’d be
looking anyway.

Good luck.–
The original message included these comments:

the ecu looks to be nice and clean… if I am looking at the ECU!
this car also didnt include an owners manual… :frowning: but there is
two modules in the fuse box in the trunk… I think one has a
sticker for seat module or something, and I assume the other one is
the ECU??

–
Regards, Bruce. 1995 XJ Sport 4.0
Colchester, Essex, United Kingdom
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24

Ron,

The engine management computer is located in the passenger side front
footwell … in the kick panel area. It’s mounted in close proximity to the
transmission management computer. It is NOT located in the trunk or engine
bay. It is a Lucas GEMS unit.

Normally, the last thing you would consider to be faulty is the engine ECU
as they are quite reliable. But these devices can fail and the firmware can
be corrupted. Based on your descriptions concerning troubleshooting, I
would strongly advise finding a good used engine ECU. You can likely find
one from the usual parts suppliers that handle used or salvage components.
If you are not getting any engine diagnostic codes, something is very amiss.

From personal experience, I can state that if the malfunctions seem somewhat
random and illogical in nature, it is a real possibility that you have a
computer fault. If the type of odd driving performance characteristics
cannot be readily explained by the failure of another component … and
there are no electrical faults, then it’s time to look at the brains of the
system.

Good Luck,
John P.

25

In reply to a message from John R. Pring sent Fri 16 Feb 2007:

This sounds like a more severe version of my problem. Heavily
sooted plugs were causing ignition problems most recently a falied
coil and 030x codes. I just changed the plugs to rc12yc and am
waiting to see if it comes back. Fuel economy for the xjr6 is at
11.7 mpg(us) around town over 1000 miles, so worse than my old xj12.

The cracked exhaust manifold is an interesting diagnosis. How do
you know if it’s cracked, is it just a visual inspection? If so
where to look?–
Mike
Vero Beach, Florida, United States
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26

In reply to a message from Mkez1 sent Fri 16 Feb 2007:

Mine had residue on the heat shield.I removed manifold and found
another, hidden crack. Nick–
The original message included these comments:

The cracked exhaust manifold is an interesting diagnosis. How do
you know if it’s cracked, is it just a visual inspection? If so
where to look?

–
Nick ,67E-Type 67S-Type 65S-Type96VDP
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27

In reply to a message from eyeinstine sent Thu 15 Feb 2007:

Are you comfortable with the condition of your battery cables?
Have you verified that the connection at the firewall is a good
one? You can have ground problems that manifest themselves in
strange ways.
Have you looked at the electronic EGR valve? When these go bad,
they can cause strange behavior also.
I will say you have everyone’s attention on this one.–
The original message included these comments:

Okay folks, you may have seen some of my recent posts… Im having
some troubles and im stumped! My wife wrecked our 95xjs last
month. I bought a 97 xjr with 85000 miles and had it shipped to me
here in NJ… I believe the dealer when he said it ran fine there

–
uncle
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28

In reply to a message from uncle sent Fri 16 Feb 2007:

On the v8 cars trouble codes P30X (misfire) show up when the
secondary timing chain tensioners have failed. The six
cylinder may have a similar design.

Tony
98 xjr–
Madonna Radcliff
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29

I just had this flash vision of you sitting behind the wheel and, when the
Moby Dick sound come on, hearing you thunder, al� Gregory Peck, “She
RISES”

(if you never saw the c.1955 movie this means nothing)

(anyone remembering the movie will know what I mean) :slight_smile:

Sorry about the thread hijacking :slight_smile:

Doug Dwyer
Longview Washington USA
1995 XJRFrom: “Tim” timish@pacbell.net

I blew the hose clamp off that kevlar or whatever hose section under the
intercooler and the car was making horrible Moby Dick whale noises on
acceleration.

30

I take it, then, that they can be cracked but you don’t hear an exhaust
leak, as might be expected ?

Doug Dwyer
Longview Washington USA
1995 XJRFrom: “Nick Hand” flynp170@cablelynx.com

Mine had residue on the heat shield.I removed manifold and found
another, hidden crack. Nick

31

In reply to a message from John R. Pring sent Fri 16 Feb 2007:

Passeger or driver side? Alas, I’m thinking of a RHD
car…sorry for any confusion.–
The original message included these comments:

The engine management computer is located in the passenger side front
footwell … in the kick panel area. It’s mounted in close proximity to the
transmission management computer. It is NOT located in the trunk or engine
bay. It is a Lucas GEMS unit.

–
Regards, Bruce. 1995 XJ Sport 4.0
Colchester, Essex, United Kingdom
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32

Sometimes after buying a used car it becomes abundantly apparent why it was
traded in…

Doug Dwyer
Longview Washington USA
1995 XJRFrom: “eyeinstine” eyeinstine@yahoo.com

it was a used car lot over in near Statesville… I probably should
have checked here first, but the pics looked great… the saleman
seemed like a straight shooter… I still believe him… I feel this
is something that happened with the battery cable issue, or it
really is okay in warmer weather… I cant imagine he knew… I

33

In reply to a message from eyeinstine sent Thu 15 Feb 2007:

Ron,

A couple ideas:

Do check the rear trans mount. I suspect on all the 05-97 XJRs
these are probably worn. It lets the trans move around. On my car
it pulled randomly on the wire harness to the transmission. This
caused an short internal to the main connector where the hareness
attaches to the trans (large round connector). The engine and
trans electronics ‘‘talk’’ to each other so perhaps you are getting
an intermitent short somewhere. My car had a differnt failure mode
(#1 solenoid in trans)but it is worth looking at. If you can get
the car on a hoist, wiggle, push, pull every harness in sight while
the car is running to see if you can recreate the condition.

Also, you may want to replace the crank position sensor (CPS) just
to rule it out. This is another common problem. My issue was a
random no start. Just a tip, when it is running poorly, is the
tach at 0 RPM? The tach circuit is connected somehow to the CPS.

There are many relays that are part of the fuel and engine
management system. Pull every relay out and look at the terminals
for corrosion. There is a typical problem for the 3 relays behind
the front right headlamps. Check these. Also, You will find many
common relays all over the car. Original ones where blue (Hella I
think). Jag superceded them with brown, then superceded with
black. Search the archives - a lot of info on this.

I recently found water under my rear seat cushion. There is a lot
of wiring under there. Maybe you are getting water into something
there. I think the source was where the floor pan meets the side
of the car near the bottom rear corner of the rear door opening.
Your need to take the cushion out to see it. There is a 1/2’’-ish
hole in the stamping with some tape over it. Well, the tape was
barely on. I suspect water was coming in that hole. Just an idea.

Buy the Jag factory manuals on CD. There is a link on the Ja-
Lovers site somewhere. Many suppliers sell it. It it had tons of
info.

Subscribe to Alldata.com (no affiation). You can get factory
Technical Service Bulletins there. Again, money well spent. That
is how I found out about the corrosion on the relays.

There are a lot of great minds in this forum. They have helped me
fix my car. We will get you fixed!–
Carel Allen, 95 XJR
Ann Arbor, Michigan, United States
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34

OMG I am sitting here on the couch with my fiance next to me and I am
laughing so hard reading this!!!

HAHAHA

Good times!

XJRGUY> From: Doug Dwyer dougdwyer1@comcast.net

Reply-To: x300@jag-lovers.org
Date: Thu, 15 Feb 2007 18:54:38 -0800
To: x300@jag-lovers.org
Subject: Re: [x300] 97 XJR problems… Im STUMPED! help!

I just had this flash vision of you sitting behind the wheel and, when the
Moby Dick sound come on, hearing you thunder, al� Gregory Peck, “She
RISES”

(if you never saw the c.1955 movie this means nothing)

(anyone remembering the movie will know what I mean) :slight_smile:

Sorry about the thread hijacking :slight_smile:

Doug Dwyer
Longview Washington USA
1995 XJR

From: “Tim” <@timish>

I blew the hose clamp off that kevlar or whatever hose section under the
intercooler and the car was making horrible Moby Dick whale noises on
acceleration.

35

In reply to a message from Doug Dwyer sent Fri 16 Feb 2007:

That’s the way it was on mine. I had never had an exhaust leak I
could not hear before. Nick–
The original message included these comments:

I take it, then, that they can be cracked but you don’t hear an exhaust
leak, as might be expected ?

–
Nick ,67E-Type 67S-Type 65S-Type96VDP
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36

In reply to a message from Nick Hand sent Fri 16 Feb 2007:

I’ll throw this out there but I had a similiar problem in my V12
and for months I had problems with the car one minute running like
a scalded cat and the next it would barely make it up my driveway.
When it was bad it would miss and bog down so low I could of pushed
it up a hill.
Turn it off, restart it, and rubber was left…

After replacing way too many parts I sent the computer in for a
check to AJ6 Engineering, they immediately found the fault and when
it came back the car ran like it had dual turbos.

A friend also had problems with his and it was his TPS.

If you can, find a friendly Jag wrecker with a similiar M/Y and ask
to try another ECU. Most will, as if it fixes it, they have a nice
sale.
Randy–
–>1987 XJ40 Sov.3.6L
Victoria BC, Canada
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37

In reply to a message from BCMedic sent Fri 16 Feb 2007:

As I said do check the transmission loom, a Jaguar main dealer
found my problem within 30 mins, so I think the trans loom is very
suspect on the X300.
Also have you tried diagnosing the problem at a rolling road
specialist they might be able to help; they might be able to find
out what is causing the problem.
http://www.jag-lovers.org/v.htm?1164449229--
Mike 1995 XJR Auto Plymouth Devon
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38

In reply to a message from eyeinstine sent Fri 16 Feb 2007:

Just be a bit careful about interpreting sooted plugs as running
rich. They may well be, periodically, but all bets are off on plug
colour if you have a misfire. Sooted plugs on a well-running engine
are rich mixture, but on a misfiring motor there are other reasons
for unburnt fuel, to do with intermittent sparking.

Meanwhile, the apparent symptoms of lean running/ fuel starvation
are more similar to electrical hiccups than the typical woolly
misfires you get from rich running. So my bet is on electrical
issues producing the symptoms you describe AND the sooty plugs.

Good luck, we’re all rooting for you…–
The original message included these comments:

Im also going to swap over the fuel regulator from the xjs… im
starting to wonder about that… since there plugs are sooted, and
fuel mileage is real bad… theres no real way to test the
regulator…??

–
Peter Crespin 66 2+2 E-type, 74 Daimler 4.2
Cambridge, United Kingdom
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39

In reply to a message from Peter Crespin sent Fri 16 Feb 2007:

You might want to try changing the throttle position sensor. I
can’t explain why the diagnostics wouldn’t pick it up if there was
a problem with it, but if you can borrow the part off your XJS it
might be worth a try. Erroneous signals from this sensor could
generate all manner of problems. Only problem is it’s difficult to
get to on an XJR.

You seem to have tried just about everything else or it has already
been suggested.

I agree with many other in it being most likely an electrical
problem of some sort.

Good luck.–
Andy Stodart - 1996 XJR owner and ex-Jaguar XJR engineer
Northampton, United Kingdom, United Kingdom
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40

In reply to a message from eyeinstine sent Fri 16 Feb 2007:

Ron,

My manifolds (both of them) were cracked just aft of the front
ports on both. i.e., between #1/#2 and #4/#5. I could never hear
any leaks thus dismissed the idea ,they could be cracked. — Until
there was nothing else to do.

The cracks didn’t look very bad when the manifolds were on the
engine. After they were removed you could see that the cracks
covered more than 270 degrees, only the flanges were intact. When
I used a die grinder and carbide cutter to ‘‘V’’ the cracks for
welding, bits of loose cast iron came out of the cracks and in some
places the crack was not a ‘‘V’’ but rather an open slot 1/4inch
wide.

New manifolds are about $300 each. Welding these things is very
problematic, inspite of that I decided to welsd them as best I
could — and start saving my SS checks for new ones. I preheated
the manifolds in my gas grill until they were as hot as I could get
them and then welded them with nickel rod that is made for cast
iron welding.

I used the die grinder to make them look nice inside and out. I
also port matched and cleaned up all of the casting/welding mess on
the inside. I also very carefully fly-cut the mating surface with
my milling machine to insure a stress free installation.

So for so good. No leaks and the long term fuel trims started
falling immediately. They started at 75 and fell to around 20.
I’m not sure why they are not at 0 but that will wait for warmer
weather.

My only explanation for the intermittent performance, would be as
the manifolds cycled through their normal temperature extremes the
cracks would change in size as the manifolds moved around. And
they will move. The block is aluminum, the manifolds are cast iron
and they are not even close to the same temperature. That’s why it
is important for the mounting surface to be smooth and very flat —
so there can be easy movement between the mating surfaces.

If you fix or replace them, make sure you use the multilayered
Stainless Steel gaskets vs. the softer asbestos ones. The SS ones
are designed to promote easy movement.

Oh, yes you must pull the heat shield. Use PB Rust Buster on the
mounting bolts and the air injector fittings, as they will be very
rusty.

Regards
Pete–
The original message included these comments:

This is an interesting idea… I did listen for leaks, but all
sounds good… Where do they normally crack, and I guess I have to
pull the heat shield to see them??

–
SpeedyPAL 1995 XJR
Milford / OH, United States
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