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Old 23rd April 2022, 11:44   #1
gliderdoctor
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Default Rover 75 1.8 intermittent engine cutting out

Hi all

Been lurking here for several years and got lots of useful info from all you experts, thanks a lot, but a bit stuck with this one.

Went to pick up the kids last week (about 20mins drive) (1.8 non-turbo, auto) engine started fine, but on setting off, every few seconds the engine would cut for about 1 second, then carry on. A few seconds later, it would do it again. I almost turned back and went home, but after about a mile, it cleared and was fine, no issues for the rest of the journey.

On coming home 10 mins later though, it was doing the same cutting out for about a second every few seconds. then it would be fine for a few minutes, then do it again.

It seems an intermittent electrical issue, because every time it cuts out the rev counter immediately drops just as if it has been turned off for a second, then comes back as normal, just as though a wire somewhere is broken but touching and making contact most, but not all the time.

Doesn't seem to have much of an issue starting hot or cold, although it does have to crank over a few times occasionally before it fires.

Any ideas you 1.8 or electrical experts?

Many thanks
Dave
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Old 23rd April 2022, 13:39   #2
suzublu
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First I would check for fuel filter separation. I'll leave the electronic stuff for the experts 😎

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Old 23rd April 2022, 15:30   #3
gliderdoctor
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Thanks Suzublu

I will have a look at the filter under the rear seat on Monday. I haven't done that already as I have made the assumption (perhaps incorrectly) that the issue is electrical in some form or other, as the instant the engine cuts, the rev counter needle just drops as though it is turned off, and a second later when the engine catches again, the rev counter needle goes immediately back up to where it should be.

I will look at the filter though, just to perhaps eliminate that as the source of the problem.

Thanks
Dave
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Old 23rd April 2022, 16:46   #4
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I think it is very unlikely to be the fuel filter as usually if it is the filter it wont start, I would be looking at the wiring that goes to the crankshaft sensor and the connectors on the bottom of the under bonnet fusebox

Dave
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Old 23rd April 2022, 17:03   #5
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Thanks Dave

Where is the crank sensor? is it obvious? I assume it has an electrical connector of some sort on it that may be loose or or the wiring chaffed somewhere. also I will have a look at the underbonnet fusebox for loose connectors, etc.

Thanks
Dave

PS What does the crank sensor actually do once the engine is running? I understand the crank and cam sensors inform the ECU of the crank and cam positions for the timing, etc, for engine starting, but what do they actually do once the engine is running?
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Old 23rd April 2022, 18:10   #6
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Default 1.8 non-turbo

Hi Dave,

I can answer your questions using RAVE (I don't have a 1.8).
Quote:
Originally Posted by gliderdoctor View Post
Where is the crank sensor?
It's mounted on the front of the gearbox housing in line with the flywheel.
Quote:
Originally Posted by gliderdoctor View Post
What does the crank sensor actually do once the engine is running?
It enables the ECM to control ignition and fuel injector period and timing. If the signal is missing, the engine will stop running.
Quote:
Originally Posted by gliderdoctor View Post
I understand the crank and cam sensors inform the ECU of the crank and cam positions for the timing, etc, for engine starting, but what do they actually do once the engine is running?
The camshaft position sensor (CMP) is also required by the ECM to complement the data from the crankshaft position sensor. If its signal is missing the engine will still run but with a reduction in performance and driveability.

By the way, your profile says that you have a diesel. If it's out of date, can you change it please?

Simon
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Old 23rd April 2022, 19:26   #7
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Hi Simon

Thanks for the info - that great.

Yes, I still have a diesel - a 2005 auto connoisseur tourer - brilliant car, I love it. Just gone over 200,000 miles, and the way it drives it still has another 200,000 in it!!!

The wife had a 2004 diesel manual tourer, but we live right next to the RAF Museum at Hendon, London, and the kids go to school inside the North Circular road, and the wife works in the city. With the new London ULEZ coming into effect last year, the Rover 75 diesels were subject to the £12.50 daily charge for going anywhere inside the North / South circular roads, so one of them at least had to go. As I work outside of London, I have kept my diesel auto tourer, but the wife has now got a 54 plate 1.8 auto tourer as the 1.8 from around mid 2003 onwards is the only Rover 75 that meets the London ULEZ rules.

We didn't really want to get rid of either of the diesel tourers, but with these ULEZ rules, at least 1 had to go, so now we still have 2 Rover 75 tourers, but only one is diesel, and the other is a 1.8 petrol!

The 75's are brilliant cars, it's such a shame that the newest ones are 2005 (my diesel tourer is one of the last built), and as such they are starting to get a bit long in the tooth, but I'm sure there will be many still on the roads for quite some time yet.

I just need to get this intermittent cutting out on the wife's 1.8 sorted out, and she will be happy. She didn't really want to get rid of her diesel tourer, but was forced into it by these new London ULEZ rules!!

Thanks
Dave
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Old 24th April 2022, 07:05   #8
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Default London ULEZ

Quote:
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... the 1.8 from around mid 2003 onwards is the only Rover 75 that meets the London ULEZ rules.
You'll no doubt be pleased to know Dave that this isn't the case! I know of a 2002 MG 190 and a 2005 MG 260 V8 which are exempt from the ULEZ charge. The only way to be sure is to enter the registration number into TfL's checker.

Simon
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Old 24th April 2022, 08:35   #9
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Is the car actually cutting out or is just a big misfire but keeps running? If it keeps running I would also be checking the coils and leads where they touch the spark plugs as they can corrode then cause a misfire

Dave
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Old 24th April 2022, 10:42   #10
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I would check the crank sensor wiring and consider putting in a new sensor- the cut out you describe and loss of revs for a second does hint at the crank signal to the ECU being interrupted.
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