[Ranger0ver]

Hi my car is misfiring on no 8 so I have changed plugs and leads
but miss is still there so will order a coil pack

but now my oil warning light comes on once engine is warm it goes off once engine speed increases past
idle but lights again on idle

question can a faulty coil pack on number 8 cause the oil warning light to come on?

a mechanic friend seems to think yes

regards Peter

 

[Richard_G]

No, oil warning light comes on with low oil pressure, nothing to do with the ignition at all. Sounds like there is enough pressure when the oil is cold but pressure drops as it thins down once it is hot. Change the oil and filter and use something like a 10 or 15W-40 or 50 as recommended. If my geography is correct, I think Perth gets pretty hot so 15W-50 is recommended for use in areas with temperatures between -10 and +50 degrees C.

 

[RRToadHall]

UHM, no RangerOver. Oil pressure has nothing to do with the ignition system.

Low oil pressure is caused by worn out oil, low oil level, incorrect oil, worn oil pump gears in the front cover or none of the above and your oil pressure switch is failing. Of course at a stretch your oil pick up screen could be partially clogged, but that's at the far end of likelihood.

 

[Richard_G]

It's possible that the unburnt fuel from the cylinder that isn't firing is getting past the rings and diluting the oil. Sniff the dipstick, if it smells of petrol change it. Even if it doesn't still change it but if it does you'll know you've found the cause.

 

[Ranger0ver]

i really did Think what the mechanic said was plausable as I'm aware of other cars having odd faults with falling coil packs such as AU Ford Fairlane v8 where coil packs upset ABS/Tracction control

Oil and filter change was the first thing I did after seeing the warning light
the engine has always run sweat and unlike what I see others say it has plenty of get up and go even keeping up with most cars from traffic lights and that's with my 3300 kg caravan on the back

ive had the car since 2008 it was purchased for the caravan
it's been serviced well and frequently using book recommended oil etc for Perth
so I'm not happy with current state

It is still think it odd that misfire started on slow point on way home from weekend caravan trip then next day at home on start-up once engine was warm oil light lit

i suppose I could borrow coil pack from my 4.0 Disco and see what happens but my gut feeling is rebuild time

 

[RRToadHall]

Well it's not a Ford. You have an American Buick engine with a German Bosch ECU and ignition system and some obscure flat geared oil pump design in the front cover. So what in the world does a Ford ABS system have to do with this topic? :roll:

A Ford Fairlane shares nothing with Rover P38s. Nor does any ABS system on any make of vehicle have anything to do with oil pressure.

So let's review, there is no connection between a misfire and loss of oil pressure or the oil sensor failing. You have two issues completely unrelated and just happened close to each other in timing. Keep the two separate and handle them one at a time.

 

[Ranger0ver]

basic electrical and electronic principles does not change also possibility of external factors causing malfunction is always plausable

the ford was mentioned as an example of how a seamngly unrelated abs/traction control is upset by faulty coil pack

So with regard to p38 my question was not about oil pressure but the electronics behind it such as becm being upset by bad coil pack and causing erroneous lighting of warning light

yes I would be inclined to say two seperate problems but with mechanic saying otherwise
and costs involved if it's more than a failed pressure switch I thought it was as worth asking here

 

[RRToadHall]

Well a few of us have given real world possibilities not obscure wild claims of Lord Lucas haunting your rig. You have not responded to most of our suggestions on possibilities. As fast as you are refuting things I seriously doubt you have tested the sensor or anything else to narrow this down.

If you are so trusting of the mechanic that claims a misfire will turn on your oil pressure light then I guess you may as well turn your Rover over to him and let him resolve your issue then.

 

[Ranger0ver]

I had already done most of what was suggested before my first post

but i did acknowledge the advise by posting this information in my later response

Perhaps it's me but It seems to happen so often in this forum that you ask a specific question as I did and you get advice you did not ask for or want and then you get insults

i did not ask what can or does an oil warning light mean
I did not ask what can cause an oil light to come on

My question was simply can a faulty no8 coil pack cause erroranous lighting of oil light?

now don't get me wrong I do appreciate the responses and some had really interesting concepts

what I don't like is the insults, which by the way can easily serve to destroy credibility of the person making them

 

[RRToadHall]

Yes, you have complained before about members here looking at the big picture and bringing options to the table you may have not thought about. That is what a forum is for. You asked "can a faulty coil pack on number 8 cause the oil warning light to come on?" The answer is no. A couple of us answered it clearly and precisely. We then looked at the big picture and gave you real reasons why an oil light would come on.

You are beating a dead horse in a realm of physical impossibilities. If you don't care for how this forum operates and folks trying to assist you then perhaps you should visit your local AULRO.