XJ6 & XJ12 Series I, II & III 1968-1992

Oh Dear

Thread Tools
 
Search this Thread
 
Old Jun 20, 2024 | 04:37 AM
  #1  
Garrycol's Avatar
Thread Starter
|
Member
Liked
Loved
Joined: May 2024
Posts: 79
Likes: 42
From: Canberra Australia
Default Oh Dear



Well was programmed to go out for a coffee with my Jag club and needed some fuel - got to the servo no issue and filled - started OK and then stopped and would not run. After three hours blocking two bowsers at the servo the tilt tray arrived and took it to the mechanic. Oh course when arrived at the mechanic, it started first go. Fuel system all clear of water so most likely moisture in the ignition - morning was -6c with hi humidity so possible. Car running OK now after being checked out
 
Reply
Old Jun 20, 2024 | 06:02 AM
  #2  
Grant Francis's Avatar
Joined: Feb 2010
Posts: 28,809
Likes: 11,279
From: Adelaide Stralia
Default

Bugga.

Being British, probably wanted Tea, not Coffee, ha.

Condensation in the dizzy cap, maybe.

Partially warm no start are a mongrel to find.

That Opus Ignition System can be a fussy sucker at times. Thats why all mine got the Crane XR700 System, but that was eons ago.

Ign switch dropping coltge in the "start" position is becoming very common. The electrical section is able to be refreshed easily, see the attached.
 
Attached Files
File Type: pdf
Ign Switch Refresh.pdf (1.58 MB, 46 views)
Reply
Old Jun 20, 2024 | 07:35 AM
  #3  
Garrycol's Avatar
Thread Starter
|
Member
Liked
Loved
Joined: May 2024
Posts: 79
Likes: 42
From: Canberra Australia
Default

Hi Francis - yes I think it was moisture in the dizzy or somewhere else in the ignition system. Soon after I got this car I washed the engine and it would not run for 5 days until it all dried out. Wont make that mistake again but it never worried the Etype.

Thankfully I no longer have the Opus system and the Jag ECU - all replaced by a more modern Motec ECU that controls ignition and fuel injection. While the installers did put a cam shaft sensor on the right bank they took a short cut and did not install a dedicated crank sensor. They locked the Dizzy and use it as a crank sensor to input to the ECU which then sends back the ignition pulses back the coil and to the dizzy - no real issues with that but it can stuff up the ignition until it dries out.

There must still be a little moisture there as the engine will not go over 5000rpm and higher than 2nd gear when floored but at sensible speeds all is good - I will use the car over the next few days to dry it all out - WD40 helps a bit.

Cheers

Garry
 
Reply
Old Jun 22, 2024 | 09:47 AM
  #4  
Garrycol's Avatar
Thread Starter
|
Member
Liked
Loved
Joined: May 2024
Posts: 79
Likes: 42
From: Canberra Australia
Default

Picked the car up from the mechanic. He said that on his test drive at about 60kph and normal throttle, occasionally the gearbox would change back down to 2nd and back the 3rd and back to 2nd etc - more or less throttle and the issue goes away.

Some 100km later the car still occasionally does this but if you manually shift to 2nd it stays there. I put this down to the engine being down on power due to still some water in the ignition, the gearbox detects this and thinks it should change down but when it does engine revs rise so the gearbox changes back to third. Alternative suggestions are welcome .

Also the engine seems to run fine up to 5000rpm but then starts missing and will not rev any higher. This equates to 140kph in second gear and with full throttle will not change into 3rd - at lower throttle the engine will have changed into 3rd at much lower speed - with our speed limits I am unable to get near 5000rpm in 3rd gear. There is no miss if the gearbox is N when you pass 5000rpm. Open to suggestions.

I feel that there is moisture still in the ignition system. At the moment the car has to stay outside and night temps are down to -3 to -6c with 90% humidity caused by heavy dew or rain. A check by the mechanic has not found moisture in the fuel system so it should be OK.

Any suggestions on any of this would be welcome.

Thanks

Garry
 
Reply
Old Jun 23, 2024 | 02:14 AM
  #5  
Greg in France's Avatar
Veteran Member
10 Year Member
Liked
Loved
Community Favorite
Joined: Jan 2012
Posts: 14,584
Likes: 10,779
From: France
Default

I would separate every connector in the system I could find and clean them.
 

Last edited by Greg in France; Jun 23, 2024 at 11:30 AM.
Reply
Old Jun 23, 2024 | 02:29 AM
  #6  
Grant Francis's Avatar
Joined: Feb 2010
Posts: 28,809
Likes: 11,279
From: Adelaide Stralia
Default

Which trans Gary, you be at a change point of sorts.

BW12, or TH400.

Both have a Vac Modulator to assist with gearchange, they play up.

TH400, easy.

BW12, HA, not so.

As for revving, Greg is on that, and I agree. Washing that engine gave you the warm and fuzzies, and messed up a connector or 2 somewhere.

The up shift, I will comment only, Greg knows this backwards,as he drives accordingly often.

TH400, lock the lecer in @1, floor it, it will up shift to 2 at a specific rev/speed, and thats it. I dont remember it going to 3 with the lever locked in 1 or 2??

BW12, NO DEA.
 
Reply
Old Jun 23, 2024 | 04:39 AM
  #7  
Garrycol's Avatar
Thread Starter
|
Member
Liked
Loved
Joined: May 2024
Posts: 79
Likes: 42
From: Canberra Australia
Default

Thanks Greg and Francis - engine was not washed after I early experience - just very cold weather and high humidity causing moisture. The gearbox is a BW12 so senses power (throttle position vs manifold pressure) to select the correct gear. When I drove it last night, as indicated it was changing back and forward from 3rd to 2nd and back constantly.

Was a bit warmer last night only to -3c but day temp was up to 15 and nice and sunny. Went for a drive and gearbox did not play up at all - so I think my hypothesis is correct that there was still water on the ignition system causing the engine to falter from time to time causing the gearbox to change down. Today no issues whatsoever - though was not able to try the engine up to 5000rpm in gears due to driving in suburbia.

So I think I need to understand that this engine is subject to moisture - like a Mini 850 and I need to keep it protected.

Thanks for all the comments - much appreciated and I will check the connectors in the system that Greg mentioned.

Garry
 

Last edited by Garrycol; Jun 23, 2024 at 04:45 AM.
Reply
Old Jun 23, 2024 | 05:01 AM
  #8  
Grant Francis's Avatar
Joined: Feb 2010
Posts: 28,809
Likes: 11,279
From: Adelaide Stralia
Default

OK, Slush a Matic trans.

NO electronics as such involved, whoopee.

BUT

The kickdown switch on the throttle cable, near the capstan, MAY BE erratic, so the thing is getting the "kickdown pulse".
Unplug ONE wire, go for a drive, see what changes, if anything.
I did not run that kickdown on any of my BW12, or TH400 cars.

I used a compact Vac Modulator, adjustable, and that was all it needed. I never liked the "mash the pedal" to change down.
Never had issues in any of them, they changed sweetly as needed.

A leaking Vac hose to that modulator could also be at play. The fact its at the LH rear, FROM the rear, its not easy to get at.
 
Reply
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
Andy T.
XJ6 & XJ12 Series I, II & III
6
Mar 7, 2024 07:01 AM
EsRay
XJ XJ6 / XJ8 / XJR ( X350 & X358 )
7
Jan 9, 2023 12:54 PM
Mad Hatter
XJ6 & XJ12 Series I, II & III
15
Sep 10, 2019 01:38 PM
purrkittypurr
XJS ( X27 )
1
May 14, 2019 04:59 AM
reid007
XJ XJ6 / XJR6 ( X300 )
2
Jan 8, 2011 03:27 AM

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 



All times are GMT -5. The time now is 08:52 PM.