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Misfire

stevemc
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Re: Misfire

Postby stevemc » Fri Sep 07, 2018 9:02 am

katar83 wrote:It's still surprising to find out how many of us here drive their Jags with no spare CPS in the boot at all times :shock:
So many kamikazes on the road, willing to risk a 12 hours wait for AA or RAC :lol:

I'd be looking at other ignition items too here. That hole as you said was as you said probably a symptom.


i can only agree with you i learned to my cost but then my own fault a 1987 car that never ever had crank sensor changed i was asking for trouble, mind you had to drill the bugger out was that welded in, at least the new one has plastic surrond not metal
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naki_k
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Re: Misfire

Postby naki_k » Fri Sep 07, 2018 11:24 am

Donkeychote wrote:I didn't think of the CPS. I'll get a new one, see if that helps. If it doesn't, I'll just have a spare :)


These can fail intermittently, or outright, or under specific conditions.
Put Crank sensor into the search box on here and there’s pages and pages of posts on this subject.
A spare should be carried at all times.
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NMV 1E
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Re: Misfire

Postby NMV 1E » Sat Sep 08, 2018 2:27 pm

Donkeychote wrote:So I finally got a new rotor arm from the local dealer. At idle it now runs beautifully, but once warmed up and under load, it still misfires badly.
With all the usual suspects now replaced, i'll have to look at more unlikely things. Is it possible that this is an ecu problem?
Or maybe the distributor isn't installed correctly, but I think I would have noticed that earlier, since I've done more than 40000km with it already.


Ooops, that's not the outcome we wanted is it :?: Very doubtful an ecu issue, though anything's possible .... I'd be checking earth's next .... ;)
Life begins at Forty !... I was born with nothing, I seem to have most of it left.


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naki_k
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Re: Misfire

Postby naki_k » Sat Sep 08, 2018 2:34 pm

Also since this issue is temperature related, I would suggest a new coolant temp sensor might be worth a go. They are cheap and easy to find.
88 3.6 XJ6 PDH/CEM
90 Range Rover Vogue SE 3.9 V8 LPG
91 3.2 XJ6 SportPack Manual
91 4.0 XJ6 Manual
92 4.0 XJR Manual
92 4.0 XJR
93 3.2s - 4.0 Manual conv
93 4.0 Sovereign
93 6.0 XJ81 DD6
93 6.0 XJ81 XJ12
94 4.0 XJR
96 4.0 X306 XJR
96 4.0 X300 D6
97 4.0 X300 Sport Manual
2000 LR Discovery ES TD5 A
Breaking 40/ 300

Donkeychote
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Re: Misfire

Postby Donkeychote » Thu Sep 13, 2018 5:15 pm

I changed the cps today, and no luck, it still misfires. All the work did improve it a bit, it's now falling back to 5 or 4 running cylinders instead of 3.
Next up; the coolant temp sensor, after that, I'll have to check earth's.
I realised a couple of days a go that the problem showed up right after it stood still for 2 months. So maybe I'll have to check wires for rodent damage.
1988 3.6 Sovereign Talisman Silver Metallic

Bruce69
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Re: Misfire

Postby Bruce69 » Fri Sep 14, 2018 1:08 pm

naki_k wrote: These can fail intermittently, or outright, or under specific conditions.
Put Crank sensor into the search box on here and there’s pages and pages of posts on this subject.
A spare should be carried at all times.


I've just started using my XJ40 as a daily driver so it sounds like I should have one of these as a spare.

Should I go for OEM or are the aftermarket ones like Lemark and Intermotor ok as a spare?
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NMV 1E
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Re: Misfire

Postby NMV 1E » Fri Sep 14, 2018 2:51 pm

Just a quick thought ... Have you checked for water, oil, or anything else none helpful, in excess, down the spark plug tubes (recesses) :?:
Life begins at Forty !... I was born with nothing, I seem to have most of it left.


2006 Baby Blue Hyundai Getz 1.4 CDX, Auto (yes I know, I know, but you'd be surprised, I was !)
1989 White and Navy Blue V.W. Golf Cabriolet (G.T.i.)
1992 Tornado Red V.W. Golf "tintop" 5 door (G.T.i.) For Sale !

NMV 1E
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Joined: Fri Apr 17, 2009 9:26 pm
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Re: Misfire

Postby NMV 1E » Fri Sep 14, 2018 2:54 pm

Bruce69 wrote:
naki_k wrote: These can fail intermittently, or outright, or under specific conditions.
Put Crank sensor into the search box on here and there’s pages and pages of posts on this subject.
A spare should be carried at all times.


I've just started using my XJ40 as a daily driver so it sounds like I should have one of these as a spare.

Should I go for OEM or are the aftermarket ones like Lemark and Intermotor ok as a spare?


Personally I'd be just happy to have one as spare. No moving parts, it's just a case of connections ... "Aftermarket" should be fine ;)
Life begins at Forty !... I was born with nothing, I seem to have most of it left.


2006 Baby Blue Hyundai Getz 1.4 CDX, Auto (yes I know, I know, but you'd be surprised, I was !)
1989 White and Navy Blue V.W. Golf Cabriolet (G.T.i.)
1992 Tornado Red V.W. Golf "tintop" 5 door (G.T.i.) For Sale !

Donkeychote
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Joined: Fri Jun 20, 2014 1:17 pm

Re: Misfire

Postby Donkeychote » Fri Sep 14, 2018 4:16 pm

Yes, I checked for dirt in the spark plug holes, and couldn't find anything. A coolant temp sensor didn't do anything either.
I've been looking around the forum, and the only one I found with a similar misfire was this: viewtopic.php?t=998097
That was a wrongly installed distributor, so I'll check that as well. It really shouldn't be, because the car has been running fine for a long time, and the distributor hasn't been off, but it is one thing in the ignition system I haven't tried already.
1988 3.6 Sovereign Talisman Silver Metallic

Steve_D
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Re: Misfire

Postby Steve_D » Sun Sep 16, 2018 4:16 pm

Have a look underneath the inlets where the inlet manifold joins the head via an insulating plastic layer. Mine had a completely solid cyl 5 misfire due to the paper gasket having worked its way out from the underside of cyl 5's inlet from the manifold - the underside of the inlet pipe is straight and the gasket is thin and unsupported there - mine broke at the centre and popped out but it could not be seen from above and the huge amount of unmetered air getting in via the gap diluted the mixture to the point of non-flammability. Just a thought as I was driven nuts by this until I found it - it was a 1988 3.6.


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