I am 2 months or so in to Jaguar ownership (well, “proper” Jaguar ownership that is, my old XF doesn’t count!)
My girl is a 1985 UK Series 3 Sovereign as pictured below, with 131,000 miles on the clock.
She has been running like a dream since I bought her, however recently a small issue has reared its head.
I noticed it for the first time the other day, that she would accelerate up to a speed with RPMs at 2000 but then would struggle to go on past that.
I thought it was strange, but hoped it was some bad fuel perhaps. I then parked up and drove later and there was no sign of the issue.
Fast forward a week later and the issue has occurred again - a hesitancy and unwillingness to Rev much past 2000 rpms but on an intermittent basis.
A friend has suggested it could be the distributor on the way out, but I would greatly appreciate any other ideas. It might be just my increased awareness as I’m looking for issues more closely but the idle seems to be slightly lumpier than before, too.
-Check elbow for airflow meter, make sure clamps are tight & secure
-Inspect throttle cable, nuts may be undone
-Check ground or loose wire
-Buy tune-up kit, change plugs, wires distributor & amplifier/coil on head
-Fuel Pressure regulator, must change
-Change fuel filter
It’s then one of those tricky ones, Jack - it’s so much easier to work on if the engine won’t run…
Intermittent faults can only be effectively pursued while the fault is present - requiring patience; changing parts willy-nilly is a last resort. There is no pat answer to your problem, but confirm that the tack revs seemingly followed the actual engine rpms. And if the event occurred while accelerating or under load…
That it is long period intermittent, and the engine doesn’t actually quit, implies that most parts are working as they should. You should definitely check the possibility that coolant is dripping onto the distributor lid from a leaking hose. It will cause misfiring, and then disappear as coolant evaporates; wipe the dist lid clean and spray on some silicon…
It may also be some water in the petrol, supposedly filtered out by the fuel filter - how long since it was changed? But the engine will misfire if injectors feed it water, until digested - there is never much water present, but a little may briefly interfere.
Certainly, a bad electric connection may be intermittent; do the ‘wire shaking’ test. With the engine idling; shake all accessible wires - the engine will react if there is a bad connection in the area shaken. With firm connections there will be no reaction…
Welcome on board by the way - sorry that a firm solution cannot be presented…
Frank
xj6 85 Sov Europe (UK/NZ)
**
Kirbert
(Author of the Book, former owner of an '83 XJ-S H.E.)
11
In the early V12 H.E., dual ignition coils are used. If the secondary coil is bad or gets disconnected, the engine runs fine at low speed but runs out of ooomph at about 4000 rpm. This sounds similar enough to what’s happening here that I’d suggest looking at the ignition system.
I’m sorry not to be able to add any suggestions to what has already been offered, Jack but I just wanted to say welcome and that is a beautiful looking car!
Four items to check: 1)auxilary air valve 2) ignition amplifier 3) coil 4)distributor cap & rotor
I had the same problem some years ago with my 1986 XJ6. It happened twice. Once, problem solved replacing coil, second time replacing auxilary air valve.
You have a beautiful car, I’m sure it’s been residing in an enclosed garage throughout much of its existence. Pepperpots look great. As you can see, I’m a big fan of pepperpots as well.
Congratulations, what a beautiful car. Does the rev hesitancy happen only with the engine properly warmed up? Does it rev normally again if you select P or N?
Started up fine, drove out of my garage and accelerate up to 2k and it was happening again. A reluctance to keep accelerating much past 2k, and a bit of light coughing, down on power not much more to give.
Pulled over to a stop, put in P and revved up to 3k, very happy to rev. Went to a shop and returned, drove a bit more, gently, until she had warmed up again and then tried to accelerate harder again.
Wow she came back, happy and purring and ready to take on the world. Locked the trans into 2 and she was very eager, really happy to go right to 4k and beyond. As if nothing was ever wrong.
So, it looks like when she heats up the problem is gone. Does this help with the diagnosis?
