Electrics: 850: - Ignition Coil - Page 2

Nick850GLT · Jun 28th, 2024, 11:16

Quote:

Originally Posted by PSJVTHEBEST

I had read that both camshaft position and crankshaft position sensors play up and can display the symptoms you're experiencing but, as I said, the crankshaft one was the culprit in my case although the camshaft one is easier to change!

My apologies - I mis-read your original helpful post, not realising at that time there were actually 2 position sensors! (can't quite see why). I've gone and ordered the camshaft one now - I guess given the modest cost if I end up doing both there is little lost. Thanks again for your help, will update when the saga concludes. P.S. Just decided to order both sensors as the cost isn't much compared with a garage bill.

PSJVTHEBEST · Jun 28th, 2024, 15:02

Yes, let us know. Apologies in advance if it doesn't fix it!

Nick850GLT · Jun 29th, 2024, 20:03

Well the new crankshaft/RPM sensor arrived today and is now fitted - sadly still no improvement. The Royal Mail didn't deliver the camshaft sensor, so that awaits Monday. Fingers still crossed!

PSJVTHEBEST · Jun 29th, 2024, 20:18

Quote:

Originally Posted by Nick850GLT

Well the new crankshaft/RPM sensor arrived today and is now fitted - sadly still no improvement. The Royal Mail didn't deliver the camshaft sensor, so that awaits Monday. Fingers still crossed!

Absolutely. Fingers crossed!

Nick850GLT · Jul 3rd, 2024, 16:11

The Camshaft sensor finally arrived today and is now fitted. Sadly no improvement at all, it is just added to the list of things I've changed to no avail. The engine continues to run rough - it still sounds like it isn't running on all cylinders. but I've now been through all the likely electrics and sensors, as well as doing a compression test.
I think it is time for the garage to see if they can find it!

PSJVTHEBEST · Jul 3rd, 2024, 17:41

It's a tricky one. As I'm sure you know it's usually either spark or fuel related but if you've checked you have spark at the plugs and your fuel pressure is good at the rail then without taking off the rail and checking the injectors are ok and they are firing as they should maybe the best bet is a garage if you have a good indi you can trust?

Luxobarge · Jul 3rd, 2024, 17:46

Just one more test that I'd be doing just to be sure - take the black spark plug cover off and run the car in the dark. It'll have to be quite late at this time of year, (the darker the better) but in the dark it's amazing how many stray sparks can show up. I know you've changed the HT leads etc but they're probably after-market ones and some of these can be of questionable quality. The "run it in the dark" test is quick and easy, and of course free - if you have NO stray sparks you can be confident that the HT side is fine IMHO.

PSJVTHEBEST · Jul 3rd, 2024, 17:59

Quote:

Originally Posted by Luxobarge

Just one more test that I'd be doing just to be sure - take the black spark plug cover off and run the car in the dark. It'll have to be quite late at this time of year, (the darker the better) but in the dark it's amazing how many stray sparks can show up. I know you've changed the HT leads etc but they're probably after-market ones and some of these can be of questionable quality. The "run it in the dark" test is quick and easy, and of course free - if you have NO stray sparks you can be confident that the HT side is fine IMHO.

I totally endorse Luxobarge's suggestion.
At 240,000 miles, the injectors could be clogged too! Checking them involves a bit more work!

volvo2 · Jul 7th, 2024, 15:21

Quote:

Originally Posted by Nick850GLT

Interested to know if you have got anywhere with this?
I have the same car - also in Worcestershire (Malvern) - with 250k on the clock. The engine has just started to run a bit rough - juddering a bit a low revs.
Initial diagnosis was a random misfire, so I replaced leads, plugs, rotor arm and distributor cap - all to no effect. Back to wondering if the coil might be in partial failure.
Various folk have suggested air leaks - but I can't find anything.

Yes, I cleaned the Idle control valve, replaced the fuel pump relay, distributor cap, rotor, and cables, along with the cam shaft sensor, and thankfully the problem went away.

Nick850GLT · Jul 7th, 2024, 16:38

Quote:

Originally Posted by volvo2

Yes, I cleaned the Idle control valve, replaced the fuel pump relay, distributor cap, rotor, and cables, along with the cam shaft sensor, and thankfully the problem went away.

Thanks for responding. Any idea which item actually did the trick?
As far as I understand it, the idle control valve could cause erratic idle (revs varying), but perhaps not the rough/judder I've got.
Also, did you change the coil?
The garage has my car at the moment - and have just had a total failure, car now won't start and they think the coil has died. I'm just hoping that isn't a mis-diagnosis caused by something else, like the brand new crank sensor! (Too many times I've seen the newest item die, with a journey up the garden path resulting)
After that cleaning the throttle body and chasing fuel problems may be on the list.

Thanks to others for various suggestions. Will update as and when.....

Jun 29th, 2024, 20:03	#13
Nick850GLT New Member Last Online: Jul 8th, 2024 23:40 Join Date: Nov 2010 Location: Malvern	Update 1 Well the new crankshaft/RPM sensor arrived today and is now fitted - sadly still no improvement. The Royal Mail didn't deliver the camshaft sensor, so that awaits Monday. Fingers still crossed!

Jul 3rd, 2024, 16:11	#15
Nick850GLT New Member Last Online: Jul 8th, 2024 23:40 Join Date: Nov 2010 Location: Malvern	Cam sensor now replaced The Camshaft sensor finally arrived today and is now fitted. Sadly no improvement at all, it is just added to the list of things I've changed to no avail. The engine continues to run rough - it still sounds like it isn't running on all cylinders. but I've now been through all the likely electrics and sensors, as well as doing a compression test. I think it is time for the garage to see if they can find it!

Jul 3rd, 2024, 17:46	#17
Luxobarge Premier Member Last Online: Jul 6th, 2024 10:05 Join Date: Jan 2011 Location: Horne (Nr. Horley)	Just one more test that I'd be doing just to be sure - take the black spark plug cover off and run the car in the dark. It'll have to be quite late at this time of year, (the darker the better) but in the dark it's amazing how many stray sparks can show up. I know you've changed the HT leads etc but they're probably after-market ones and some of these can be of questionable quality. The "run it in the dark" test is quick and easy, and of course free - if you have NO stray sparks you can be confident that the HT side is fine IMHO. __________________ Some people are like Slinkies, they serve no useful purpose but they still bring a smile to your face when you push them downstairs.

Jun 28th, 2024, 15:02	#12
PSJVTHEBEST VOC Member Last Online: Jul 8th, 2024 13:24 Join Date: Dec 2002 Location: Tiverton	Yes, let us know. Apologies in advance if it doesn't fix it!

Jul 3rd, 2024, 17:41	#16
PSJVTHEBEST VOC Member Last Online: Jul 8th, 2024 13:24 Join Date: Dec 2002 Location: Tiverton	It's a tricky one. As I'm sure you know it's usually either spark or fuel related but if you've checked you have spark at the plugs and your fuel pressure is good at the rail then without taking off the rail and checking the injectors are ok and they are firing as they should maybe the best bet is a garage if you have a good indi you can trust?

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