Further re. Paste. Just replacing the ignition amplifier on my Lucas ignition, so read up on thermal paste. Apparently more is less. Around a pea sized glob per square inch or so is all that is needed based on PC processor usage. Don't spread it, just place glob(s) and then squeeze the module in place.

 

That could also be a plugged fuel filter. Cheap enough to change on general principals. Other thing it could be is a failing coil, they sometimes don't like heat.

 

Finally got to the car, tested, yes, exactly 5-6 inches down the hole there is sort of a plate, so lets assume its done right

now, while removing both ignition amplifiers, i broke one of them , dont ask me how. So ordered new one, as well as new coil(just in case)

so i will repace broken one, will replace fuel filter, cTS sensor

what else i can do/check? How do i check which coil is failing?

Also still no clue about overheating

 

When mine was flaky it would misfire occasionally. I felt it as a little thump in my lower back when driving. Went away when I changed coils. I bought them off Rockauto, they were quite cheap.

Have you checked the ignition timing? Retarded timing can make an engine run hot.

 

Got ya, indeed i did feel thumps, especially on idle. Anyway, got only 1 coil, should have ordered both, will try to swap them around.

ingition timing? but as far as i know on marelli you cant really anything about timing

 

Correct re marelli timing.

 

Greg hi, just read the book again and found this, which does look a lot like my problem
"CATALYTIC CONVERTORS -- MELTDOWN (SECONDARY DAMAGE): Greg Maddison says, “Also check the
engine speed sensor located on the flywheel housing. It is a $40 part located very near one of the catalysts. Mine
melted when the catalyst overheated. After that the speed sensor became temperature sensitive, car ran well when it was
cold. After it warmed up the car wouldn't develop any power and couldn't go over 40 MPH.”"

is the engine speed sensor they are talking about is crankshaft speed sensor? any idea what is the part number? tried to look, but i get completely different results from $40 to $400 dollar tag

 

Yes, it is the sensor on the rear of the engine.

 

mouserider,

Part identified as always on the Jaguar parts website. See here:

https://parts.jaguarlandroverclassic.../brand/jaguar/

Cheers

Paul

 

Hey all, good news and bad news, good news is that my jag still looks awesome in my garage.

so, as i told before, one of my amplifiers didnt have fresh paste and second one i broke while removing it (lesson learned).

got new one from Barratt, replaced broken one, put a new paste on the old one. Also replaced both coils.

This thing(v12) now doesnt really want to raise RPM even on idle, even cold. Going up veryyyy slowly and i can smell fuel and sometimes clapping sounds from the back and no tach speed on tachometer.

Now, its either new one defective, or old one completely burned out or.. smth else

which one responsible for tach output?






I have ordered new one anyway, but not original as its damn expensive, but i found out that VE520225 Cambiare is alternative (hope its true)

Anyway, while im waiting new amplifier, i want to check all ignition components

cap is new


Rotor looks good, but have black silicon at base.

Does it look like a modification explained in the book that was done by someone prior to me?




spark plugs, plugs all new , but harness is old!

CTS i just replaced with new, but didnt run the car yet
Also replacing now fuel filter, old one was very very dirty and quite blocked (will report tomorrow)

What else can i check and test before new amplifier arrives?

crank speed sensor from the back of the engine? can he do what my car does now?

 

This sounds like a blocked exhaust to me. What state are the cats in?

 

will check that one’s car cools down. So I just swapped amplifiers with each other and still no tach output, idle throttle response still laggy and strong fuel smell. Also!! On the A bank exhaust , fumes are cold, on b bank hot as they should be, a bank not working?

 

Bank not working, for sure.
Have you renewed the injection loom? If not that is a prime suspect as the fuel smell is the injectors remaining open because of a faulty loom and failure to fire because of flooding.
Also:
Pull a plug that side and see what it looks like.
Get someone to turn over the engine on the starter while you check for spark on that side.

 

oh damn, I will, but how is that , after I replaced amplifiers, broke one, tach still not working , even after swapping amplifiers and one bank failed . The only thing I haven’t change is harness, as it’s not sold for my car anywhere and only few people can redo it, but I had to send my one prior. Thought to do that next year. But thats strange as several things failed at once , amplifier, tach, a bank.



update: checked spark on A coil - no spark. ( coil is brand new) , connected old coil - spark!!

Now I have to also check new parts, noice!

 

Good find. replace the coil and seewhat happens.

Get the coil fixed first, but if needed new harnesses are available eg
https://www.autosparks.co.uk/jaguar-...ring-harness-1

 

alright, I fixed what was not broken, old coil works, tach works, throttle response back to normal at least on cold idle. Now (after spending another $400) I’m back where I was. I will check now if it overheats and losses power as it was. I haven’t check cats (btw how do I check them please? )

 

You can use a manifold vacuum gauge as a rough check of exhaust restrictions. At idle, should be about 17”; raise to 3000 rpm and hold steady- vacuum should momentarily drop then increase back to at least 17”. It should remain steady, when the throttle is released to idle, vacuum should momentarily go up to 20-22” and then stabilize at the original idle vacuum (17”).
Restrictions in the exhaust result in low vacuum at idle, dropping or low vacuum at 3000 rpm when throttle held steady; also vacuum usually won’t rise to 20-22” when the throttle is released.
I recommend anyone new to vacuum gauges to connect one to a well running car first, to learn how they should act.
you can also remove the two oxygen sensors and connect a pressure gauge; should never go over 1-2psi, even under load. I guess you could road test it with the sensors removed to provide a little less restriction (or loosen both side exhaust flanges at the manifolds - 4 total/8 nuts). It will be noisy.

 

Okey, so replaced the broken coil, new fuel filter, new CTS, tried to add coolant as much as i can with left corner raised. for now no acceleration problem!!

So, test drive - 20 mins, small village drive, no traffic, no high speed, a lot of turns. first 15 mins all good, temp gauge goes a bit to right part of N letter and then back to middle N. Like that back and forth, then after 15 mins, it started to slowly slowly goes higher and higher, accelerations didnt really do much to it, while i get back to the garage it was like that and it stayed there for another 10 mins of idling and only then started to go a hair down, but still was above N when i switched off the car.

Please see reading at this temp


B bank






A Bank




Please note my e-fan connected to rear A bank housing (in the place of hot air vacuum switch??)

Bot efans jumps in right in the high point of N and while driving they never went off.

 

updated: i did vacuum test, everything looks normal, except idle vacuum is at 16 , not 17.

 

That is good; a small difference at idle is of no consequence. As long as it behaved above idle, your catalyst system is probably ok.
I wonder if your gauge sender location (I think you said you relocated it to the rear of the rail?) may be influencing the readings. You could try wiring your main e-fan to be on with ignition and put the gauge sender back to the OE location and see what happens.
My ‘88 V12 with 110K, original radiator, mechanical fan (black fan and new clutch) never fluctuates much, always on the bottom of “N”, unless prolonged idle in high ambient temperatures, where it might get to the upper “N”. Maybe the back of the water rail fluctuates more….