BREAKDOWN DUE TO IGNITION FAILURE - HELP!

[Clive]

After five months of starting every morning on the button and super smooth running, my "new" 1992 XJ40 3.2 refused to start last Thursday afternoon in the office car park. The engine was cranking over nicely but she was not firing at all and the AA man found the cause as no HT (but LT present) and reckoned that the ignition amplifier was dead. So the car was towed to my local garage where it awaits repair. Yesterday I went over to Legacy Jaguar in Wrexham for another amp. I had a good chat with the boss David Kelly and he said the prime suspects were usually the amp, crankshaft position sensor or the ECU if it had suffered water damage - located behind the glove box and gets wet if the screen leaks (but you usually get water in the passenger footwell and my car is bone dry inside.) So tomorrow Monday the fitter will first swap the amp and then crank sensor. ( Nigel Thorley in his XJ40 book says these can suddenly fail and then repair themselves a couple of days later!). I sincerely hope that she fires up tomorrow but if she doesn't, any ideas please or other possible culprits?
Many thanks
Clive

[jagtech]

It seems that the garage owner has experience with jaguars but little diagnostic skills or equipment. I would suggest taking the car to a garage who can diagnose and identify the failed component not just guess at the likely cause, replace the component and hope it fixes the fault.
This is the difference between mechanic and a technician.
Having said that i wish you luck in getting your beloved jag fixed and regaining your trust in the car.

[Clive]

Thanks for your good wishes and happily the problem easily fixed and back on the road! It was indeed the crankshaft postion sensor. I ended up getting two and also an igntion amp so I now have spares of possibly the two most vital ignition components to carry around in the boot. Scrappers are selling the crank sensors for about £20 and the amp for £30 or so with both still available new through Jaguar themselves and independents such as Britparts. Very educational for me as my previous classics have used traditional points ignition.
Clive

[steve_m]

So, I ma sat here going through threads whilst sat in a layby awaiting a breakdown truck., in my 95 XJR6.
Neither me or the RAC man know what the fault is as no error codes recorded.
I noticed whilst sat in traffic (right at the start of a 208 mile trip) that the idle was high at about 1400 rpm.
60 miles late, doing 70 on a dual carriageway, the engine hiccupped once so I headed to the inside lane.
A few seconds later it died on me, luckily just as I was approaching a layby so managed to coast in.
Tried starting it and it would run hesitantly for a seconds then die again.
RAC chappie turned up and had a play (after it had cooled down a bit) and it ran quite nicely for 5 or 10seconds than cough, splutter, die.
Plugs are fine (less than a year old) and nothing obvious showing.
MAF?
TPS?
CTS?
There was a bit of smoke at the exhausts whilst it was farting.

[davidr]

Hi Steve - that's no fun!
You mention the coolant temperature sensor in your list of suspects and that could give you the symptoms you have in that it will start happily but over-fuel when the engine is hot and run so rich that it cuts out. Was there a strong smell of fuel on the plugs?
Hope you get back home OK

[steve_m]

Thanks David.
The guy pulled a couple of plugs but they looked ok (new this year) and he sniffed one and didn't comment on it.
Whilst waiting (still here for another 1/2 an hour) I started it and ran fine but I did notice that the distance range was reading zero even though the tank is half full.

[steve_m]

Got home eventually.
Started the car a couple of times from cold the next day and it kicked into life ok but then idled at about 1500rpm.
I received the new CTS and will fit it tomorrow and see what happens.
Doing further research and it looks like MAF's are not available for love nor money; does anybody have a source?
Is the TPS accessible from underneath or does the whole intercooler have to come off?

[Andy P]

Hi steve_m,
Regarding getting a new MAF for the X300 I came across this on Ebay:
Spectra Premium Mass Air Flow Sensor P/N:MA184
The only downside is that it's in the U.S.A. but they do use the Global Shipping Programme which I have used quite a few times and have found it to be very good .
No import charges once in this country
Here's the link:
https://www.ebay.co.uk/itm/Spectra-Prem ... %7Ciid%3A1

Other wise Pre-Owned is the only way to go I fear.

Hope you get your problem sorted.
Looks like a very nice car.
Take care.
Andy

[steve_m]

Thanks Andy.
I followed the link and found the sensor.
I checked on the compatibility table and it doesn't list mine which was registered on 31/12/95.
The earliest XJR on the table is 1997.
I also input the details in the search box and it says that it does not fit although I do know that that function is fairly random.

[Andy P]

Hi Steve,
I was going by the part No LHE1620AA for the MAF which it lists.
I think that's right for the X300.
But I guess the XJR6 uses a different one.Which is a bit annoying
Is there a part number on your one?
Would interesting to know.
Actually it does look like the same style as fitted to my XJ8,with the removable sensor.
The photo also shows it has a four pin connector.
I think the X300 uses a three pin.
So I guess if you need one it will have to be Pre-Owned .
Take care.
Andy

[steve_m]

Yeah, mine's an LHA 1620AA which I guess is different due to the increased airflow through the charger.
Anyhow, out with the contact cleaner tomorrow!

On to the next possibility; is the TPS the same across all the AJ16 engines? I can't see any particular reason for it changing as it does the same job with the same parameters.

[steve_m]

Does anybody have a spare JLM12074 TPS for an X300 that I can borrow to see if it fixes the car problem?
I figured that I'd get a new one, it's only a sensor so not too expensive right?
Wrong!
£186 is the cheapest that I can find so far, $500 from the States.
What is it made of, unobtanium and rocking horse poop?
Rip off merchants the lot of them.

[steve_m]

replace the coolant temperature sensor which didn't make any difference.
Took the MAF off and sprayed it with contact cleaner, left it to dry until the next day.
Cleaned the connector on the crank position sensor fly lead and anything else that I could reach.
Started it up and ticked over at 1300 rpm.
Took it for a blast and the tickover dropped to a shade under 1000rpm.
Getting there slowly I suppose.

At least the interior lights are working again now.

[steve_m]

Lonely on here.
Anyway, it's seems to be running normally now.
I need a smaller car so I am going to be selling it if anyone is interested.

[J44EAG]

Will miss you, Steve.

Just a thought. Several years ago I got involved with an XJR6 which blew the "b`std hose" from the NS of the block to, I recall, the back of the water pump. We left the inter-cooler block in place and spent 9 hrs ripping out the charger, throttle body, by-pass actuator etc out to get to that burst hose. In the process we removed 36 corroded jubilee clips! This well known hose blew because it is so inaccessible that in eighteen years and over 100k miles no-one had got to it for inspection or replacement. The V8R also has a b`std hose!

All this was done from below the car and it was not nice or funny. With the charger and all the gubbins out of the way, we replaced the hose which cost around £18. We also replaced all the small bore vac and pressure pipes to and from the by-pass actuator. Then the trouble started. The throttle body throat and plate were ridged and leaking air at idle. That fault was also present besides the hose issue. In the end we acquired a good, used, un-ridged throttle body which fixed the high idle issue which this particular car also suffered. Just an idea that might be worth considering.

All the best,

Mike